EP4724442A1 - Agonism-antagonism in endosomal tlrs by modulating chemical features in 8-oxopurine: process for preparation and application thereof - Google Patents

Abstract

Toll-like receptors (TLRs) are integral components of the innate immune system, serving as key players in the recognition and response to microbial pathogens. TLR7, TLR8 and TLR9 are located inside the cell within the endosomal-lysosomal compartments, subsequently specialized for detecting microbial nucleic acids after microbes get phagocytosed and reach the endosomal compartments. The biological importance of TLR agonists lies in their ability to serve as powerful tools for studying innate immune responses, developing vaccines, and potential therapeutic applications. Additionally, TLR agonists have been explored as immunotherapies, whereas antagonists of these TLRs could serve as novel pathogenic node in different autoimmune disease contexts. Thus, both agonists and antagonists of these endosomal TLRs have therapeutic significance in different clinical context. The previous studies in 8-oxoadenine class depicted that the C-6 position -NH2 group is extremely important for recognition of the agonistic active site and subsequent interferon (IFN) induction. The present invention explores ability of 8-oxopurine derivatives, which does not contain the essential C-6 amine group and was replaced with hydrogen. The replacement of C-6 amino with a hydrogen (H) in 8-oxopurine derivatives provided exciting insight into these endosomal TLR modulation. The ability to modulate the endosomal TLRs by 8- oxopurine derivatives in correlation/interrelation with various substitution at N-7, N-9 and C-2 with all the derivatives containing hydrogen at C-6 were reported.

Description

AGONISM-ANTAGONISM IN ENDOSOMAL TLRS BY MODULATING CHEMICAL FEATURES IN 8-OXOPURINE: PROCESS FOR PREPARATION AND APPLICATION THEREOF FIELD OF THE INVENTION Structure 1 The present invention relates to the preparation of new compounds with general structure I in free form or in acceptable salt form for the modulation of TLR7 agonism and antagonism. The invention relates to small molecules where R1, R2, R3, R4 and R5 are as defined in the description, capable of modulating the activity of the molecule in such a way that a subtle change in substitution can alter the agonism and antagonism property of the compound. The proper R1, R2, R3, R4 and R5 substitution can impart TLR7 partial agonism in the compound. BACK GROUND OF THE INVENTION Toll-like receptors (TLRs) are integral components of the innate immune system, serving as key players in the recognition and response to microbial pathogens. TLRs play a fundamental role in detecting molecular patterns associated with a wide range of pathogens, from bacteria and viruses to fungi (Medzhitov, R; Nat. Rev. Immunol. 1, 135-145, 2001). In the innate immune system, various cell types, including dendritic cells, macrophages, and monocytes, along with natural killer (NK) cells, innate lymphoid cells, and natural killer T cells (NKT cells), work collaboratively to detect and respond to potential threats to the host's tissue integrity. These cells are equipped with specialized receptors like TLRs, which recognize and initiate responses to invading microorganisms. TLRs are characterized as type I membrane proteins; which is comprised of three distinct domains: an extracellular domain, a transmembrane domain, and an intracellular domain. The extracellular N-terminal domain (NTD/ECD), composed of 19-25 leucine-rich repeats is projected at the outside of the membrane and serves as ligand recognition site by forming an ectodomain. The transmembrane helix domain spans TLRs to the membrane and anchors the receptor in place. The intracellular C-terminal domain (CTD) is located towards the cytoplasm and commences various downstream signalling upon ligand binding through the interaction of its toll-IL-1 receptor (TIR) homologous domain with adaptor molecules such as MyD88. Till now, ten TLRs have been found in humans. Among them, six are expressed on cell surfaces (TLR1, 2, 4, 5, 6, and 10) which detect proteins and lipids. The leucine-rich repeats in the ectodomains of these molecules bind to unique molecular entities on pathogens (PAMPs), which detect and initiate responses to invading microorganisms (Akira, S; et al. Annu Rev Immunol. 21, 335-76, 2003). Another four types of TLRs (TLR 3, 7, 8, 9) are located inside the cell within the endosomal-lysosomal compartments, subsequently specialized for detecting microbial nucleic acids after microbes get phagocytosed and reach the endosomal compartments. The TLR (Toll-like receptor) downstream signalling pathway is a critical part of the innate immune response. When TLRs recognize pathogen-associated molecular patterns (PAMPs), they activate intracellular adaptor molecules like MyD88 (or the myeloid differentiation primary-response gene 88), TIRAP (or the TIR-domain containing adaptor protein), TRIF (or the TIRAP inducing IFN-beta), and TRAM (or the TRIF-related adaptor molecule). These adaptors initiate multiple signalling pathways, including activation of NF-κB, MAPKs (mitogen-activated protein kinases), and conscription of the IRFs (IFN regulatory factors.) These pathways lead to the activation of transcription factors that regulate the expression of genes responsible for the production of cytokines, chemokines, and other immune response components. In summary, TLR activation triggers a series of events that culminate in the expression of immune response genes and the orchestration of the body's defense mechanism against pathogens (Akira, S; et al. Annu Rev Immunol. 21, 335-76, 2003). The intracellular localization of nucleic acid-sensing TLRs (TLR 3, 7, 8, 9) serves as a mechanism to prevent their spontaneous activation by host-derived nucleic acids. TLR agonists are substances or molecules that specifically bind to and activate Toll-like receptors. These agonists mimic the presence of pathogens, and when they engage TLRs, they trigger the same downstream signalling pathways and immune responses that occur during an actual infection. TLR agonists can be natural compounds derived from pathogens or synthetic molecules designed to activate TLRs. The biological importance of TLR agonists lies in their ability to serve as powerful tools for studying innate immune responses, developing vaccines, and potential therapeutic applications. Some TLR agonists are used as vaccine adjuvants to enhance the effectiveness of vaccines by boosting the immune response to vaccine antigens. Additionally, TLR agonists have been explored as immunotherapies, particularly in cancer treatment, to stimulate the immune system's recognition and attack of cancer cells. But under certain pathological condition chronic immune upregulation act as a mediator of several autoimmune and inflammatory disorders. For instance, it has been previously reported by us and others scientists that immune complexes found in the sera of patients with systemic lupus erythematosus (SLE) typically contain nucleic acids associated with proteins such as, the chromatin-associated protein HMGB1, and ribonuclear proteins antibodies, the antimicrobial peptide LL37 and others (Ganguly, D. et al. Nat Rev Immunol. 13(8), 566-77, 2013). Once enclosed within the endolysosomal compartments, the nucleic acid cargo can activate intracellular TLRs, setting the stage for a cascade of inflammation that may induce cytotoxic or humoral responses. For instance, this recurring cycle of innate immune recognition, the generation of autoreactive antibodies, and subsequent formation of immune complexes is thought to play a crucial role in the development of systemic lupus erythematosus (SLE) and potentially Sjogren's syndrome (Ganguly, D. et al. Nat Rev Immunol. 13(8), 566-77, 2013). These proteins protect the bound nucleic acids from degradation and facilitate their entry into cells, priming the immune system for an inflammatory response as is the case for Fc receptor- mediated uptake of antibody-nucleic acid complexes (Ganguly, D. et al. J Exp Med. 206(9), 1983-94, 2009). TLR-mediated pathological responses to nucleic acids contribute to various diseases, including lung infections, pancreatitis, ischemic liver injury, sepsis. The previous studies in 8-oxoadenine class molecules depicted that the C-6 position -NH2 is extremely important for recognition of the agonistic active site and subsequent interferon (IFN) induction (Talukdar A, et al J. Med. Chem.64, 8010−8041, 2021). The replacement of C-6 amino with a hydrogen (H) provided exciting insight into endosomal TLR modulation in the present invention with 8-oxopurine derivatives with different substitutions at N-7, N-9 and C-2 position and their interrelations. The C6 position -NH2 (primary amine) group has network of interaction at the active site, where as the C-6 H will unable to attain these interactions. In the absence of such interactions, it will be interesting to study the modulation of these endosomal TLRs. OBJECTIVES OF THE INVENTION The main object of the present invention is to provide composition and methods of compounds of general formula I. Another objective of the present invention is to provide compounds of general formula I without C-6 primary amino (-NH2) and replace it with a hydrogen (H). Yet another objective of the present invention is to provide a method for testing TLR7 agonism of compounds of general formula I, a reporter assay method involving HEK cell line expressing TLR7 to screen compounds of general formula I for TLR7 agonism. Yet another objective of the present invention is to provide a method for testing TLR7 antagonism of compounds of general formula I, a reporter assay method involving HEK cell line expressing TLR7 to screen compounds of general formula I for TLR7 antagonism. Yet another objective of the present invention is to provide a method for testing TLR9 agonism of compounds of general formula I a reporter assay method involving HEK cell line expressing TLR9 to screen compounds of general formula I for TLR9 agonism. Yet another objective of the present invention is to provide a method for testing TLR9 antagonism of compounds of general formula I a reporter assay method involving HEK cell line expressing TLR9 to screen compounds of general formula I for TLR9 antagonism. Yet another objective of the present invention is to provide compounds that are useful in treating various disease conditions where modulation of TLR7 and TLR9 plays a role. Yet another objective of the present invention is to provide compounds that are useful in treating various auto-immune diseases where activation of TLR7 and 9 plays a role. Yet another objective of the present invention is to provide compounds that are useful to activate an immune system response in a subject associated with suppressed immune condition due to the suppression of TLR7 and/or TLR9 activation. They can also act as antiviral or antitumor vaccine adjuvants. Yet another objective of the present invention is to provide compounds that can selectively activate or antagonize TLR7 or TLR9 signalling. Yet another object of the present invention is to provide composition and methods of compounds of general formula I that can be used in various clinical applications, including as pharmaceutical agents and methods for antiviral or antitumor vaccine adjuvants and treating conditions involving supressed immune response as well as aberrant immune hyperactivity. SUMMARY OF THE INVENTION The present invention relates to the compound represented by following structure I or a pharmaceutically acceptable salt thereof: Structure 1 Wherein R1 is independently selected from groups referred to as follows: R₂ is independently selected from groups referred to as follows: R₃ is independently selected from groups referred to as follows:

R4 is independently selected as H. The compound of structure I as claimed in Structure I consisting hydrogen (H) at C-6 position is selected from the group consisting of: 2-butoxy-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(3-(piperidin-1-yl)propyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(3-(4-ethylpiperazin-1-yl)propyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-hydroxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-methylbenzyl)-7,9-dihydro-8H-purin-8-one 9-(4-bromobenzyl)-2-butoxy-7H-purin-8(9H)-one 2-butoxy-9-(4-(trifluoromethyl)benzyl)-7,9-dihydro-8H-purin-8-one 9-(4-(2-aminoethoxy)benzyl)-2-butoxy-7,9-dihydro-8H-purin-8-one 9-(4-(aminomethyl)benzyl)-2-butoxy-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-(2-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)ethoxy)benzyl)-7H-purin- 8(9H)-one 2-butoxy-9-(4-(2-(pyrrolidin-1-yl)ethoxy)benzyl)-7H-purin-8(9H)-one 2-butoxy-9-(4-(2-(dimethylamino)ethoxy)benzyl)-7H-purin-8(9H)-one 2-butoxy-9-(4-(2-(piperazin-1-yl)ethoxy)benzyl)-7H-purin-8(9H)-one 2-butoxy-9-(4-(2-morpholinoethoxy)benzyl)-7H-purin-8(9H)-one 2-butoxy-9-((6-methoxypyridin-3-yl)methyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-butyl-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-(2-hydroxyethyl)-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-(3-hydroxypropyl)-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 7-(3-aminopropyl)-2-butoxy-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 7-allyl-2-butoxy-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 7-benzyl-2-butoxy-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 9-benzyl-2-butoxy-7-butyl-7,9-dihydro-8H-purin-8-one 7-allyl-9-benzyl-2-butoxy-7,9-dihydro-8H-purin-8-one 9-benzyl-2-butoxy-7-(2-hydroxyethyl)-7,9-dihydro-8H-purin-8-one 9-benzyl-2-butoxy-7-(3-hydroxypropyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-butyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 7-allyl-2-butoxy-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-(2-hydroxyethyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-(3-hydroxypropyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one (S)-2-butoxy-7-(2,3-dihydroxypropyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one (R)-2-butoxy-7-(2,3-dihydroxypropyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 7-(3-aminopropyl)-2-butoxy-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-methoxybenzyl)-7-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 7-(2-aminoethyl)-2-butoxy-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-methoxybenzyl)-7-(4-(pyrrolidin-1-ylmethyl)benzyl)-7,9-dihydro-8H-purin-8- one 2-butoxy-7-cyclopentyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-methoxybenzyl)-7-(pyrrolidin-3-yl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-isopropyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-(4-fluorobenzyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-((5-fluoropyridin-3-yl)methyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-cyclopentyl-9-((6-methoxypyridin-3-yl)methyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-((6-methoxypyridin-3-yl)methyl)-7-(pyrrolidin-3-yl)-7,9-dihydro-8H-purin-8-one 9-(4-(aminomethyl)benzyl)-2-butoxy-7-butyl-7,9-dihydro-8H-purin-8-one 9-(4-(aminomethyl)benzyl)-2-butoxy-7-cyclopentyl-7,9-dihydro-8H-purin-8-one 2-(butylamino)-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-9-((6-methoxypyridin-3-yl)methyl)-7,9-dihydro-8H-purin-8-one 9-(4-(aminomethyl)benzyl)-2-(butylamino)-7,9-dihydro-8H-purin-8-one 9-(4-(aminomethyl)benzyl)-2-(butylamino)-7-cyclopentyl-7,9-dihydro-8H-purin-8-one 9-(4-(aminomethyl)benzyl)-2-(butylamino)-7-(pyrrolidin-3-yl)-7,9-dihydro-8H-purin-8-one 7-butyl-2-(butylamino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-7-cyclopentyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-9-(4-methoxybenzyl)-7-(pyrrolidin-3-yl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-7-isopropyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-7-(4-fluorobenzyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-7-((5-fluoropyridin-3-yl)methyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin- 8-one 7-(3-aminopropyl)-2-(butylamino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 7-(2-aminoethyl)-2-(butylamino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-9-(4-methoxybenzyl)-7-(4-(pyrrolidin-1-ylmethyl)benzyl)-7,9-dihydro-8H- purin-8-one 2-(butylamino)-7-(2-(dimethylamino)ethyl)-9-(4-methoxybenzyl)-7H-purin-8(9H)-one 2-(butylamino)-9-(4-methoxybenzyl)-7-(2-(methylamino)ethyl)-7H-purin-8(9H)-one 2-(butylamino)-9-(4-methoxybenzyl)-7-(3-(pyrrolidin-1-yl)propyl)-7H-purin-8(9H)-one 2-(butylamino)-9-(4-methoxybenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)propyl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(3-methoxybenzyl)-7H-purin-8(9H)-one 9-(4-bromobenzyl)-2-(butylamino)-7-cyclopentyl-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(naphthalen-1-ylmethyl)-7H-purin-8(9H)-one 9-([1,1'-biphenyl]-4-ylmethyl)-2-(butylamino)-7-cyclopentyl-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7H- purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(4-(piperazin-1-yl)benzyl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(4-(pyrrolidin-1-yl)benzyl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(4-((5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)methyl)benzyl)-7H-purin-8(9H)-one 9-(4-bromobenzyl)-2-(butylamino)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)propyl)-7H-purin-8(9H)-one 7-cyclopentyl-9-(4-methoxybenzyl)-2-(propylamino)-7H-purin-8(9H)-one 9-(4-methoxybenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-2- (propylamino)-7H-purin-8(9H)-one 9-(4-bromobenzyl)-7-cyclopentyl-2-(propylamino)-7H-purin-8(9H)-one 9-(4-bromobenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-2- (propylamino)-7H-purin-8(9H)-one 7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-2-(propylamino)-9-(4- (trifluoromethyl)benzyl)-7H-purin-8(9H)-one 9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7-(3-(5-methyl-2,5- diazabicyclo[2.2.1]heptan-2-yl)propyl)-2-(propylamino)-7H-purin-8(9H)-one 7-cyclopentyl-2-(ethylamino)-9-(4-methoxybenzyl)-7H-purin-8(9H)-one 2-(ethylamino)-9-(4-methoxybenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)propyl)-7H-purin-8(9H)-one 9-(4-bromobenzyl)-7-cyclopentyl-2-(ethylamino)-7H-purin-8(9H)-one 9-(4-bromobenzyl)-2-(ethylamino)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)propyl)-7H-purin-8(9H)-one 2-(ethylamino)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-9-(4- (trifluoromethyl)benzyl)-7H-purin-8(9H)-one 2-(ethylamino)-9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7-(3-(5-methyl- 2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H-purin-8(9H)-one 7-cyclopentyl-9-(4-(4-(dimethylamino)piperidin-1-yl)benzyl)-2-(ethylamino)-7H-purin- 8(9H)-one 2-ethoxy-9-(4-methoxybenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)- 7H-purin-8(9H)-one 9-(4-bromobenzyl)-7-cyclopentyl-2-ethoxy-7H-purin-8(9H)-one 9-(4-bromobenzyl)-2-ethoxy-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H- purin-8(9H)-one 2-ethoxy-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-9-(4- (trifluoromethyl)benzyl)-7H-purin-8(9H)-one 2-ethoxy-9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7-(3-(5-methyl-2,5- diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H-purin-8(9H)-one 9-(4-(4-(dimethylamino)piperidin-1-yl)benzyl)-2-ethoxy-7-(3-(5-methyl-2,5- diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H-purin-8(9H)-one 7-butyl-9-(4-methoxybenzyl)-2-((3-(pyrrolidin-1-yl)propyl)amino)-7,9-dihydro-8H-purin-8- one 7-cyclopentyl-9-(4-methoxybenzyl)-2-((3-(pyrrolidin-1-yl)propyl)amino)-7,9-dihydro-8H- purin-8-one 7-((5-fluoropyridin-3-yl)methyl)-9-(4-methoxybenzyl)-2-((3-(pyrrolidin-1-yl)propyl)amino)- 7,9-dihydro-8H-purin-8-one 2-((4-fluorobenzyl)amino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 7-butyl-2-((4-fluorobenzyl)amino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 7-cyclopentyl-2-((4-fluorobenzyl)amino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-cyclopentyl-9-(piperidin-4-yl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(4-methoxybenzyl)piperidin-4-yl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(4-fluorobenzyl)piperidin-4-yl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(3-fluorobenzyl)piperidin-4-yl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(2-fluorobenzyl)piperidin-4-yl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(naphthalen-1-ylmethyl)piperidin-4-yl)-7H-purin-8(9H)- one 2-(butylamino)-7-cyclopentyl-9-(1-((6-fluoropyridin-3-yl)methyl)piperidin-4-yl)-7H-purin- 8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-((5-fluoropyridin-3-yl)methyl)piperidin-4-yl)-7H-purin- 8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(4-(trifluoromethyl)benzyl)piperidin-4-yl)-7H-purin- 8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(4-methoxyphenyl)piperidin-4-yl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(4-fluorobenzoyl)piperidin-4-yl)-7H-purin-8(9H)-one 2-(4-(2-(butylamino)-7-cyclopentyl-8-oxo-7H-purin-9(8H)-yl)piperidin-1-yl)acetamide 2-(butylamino)-7-cyclopentyl-9-(1-isobutyrylpiperidin-4-yl)-7H-purin-8(9H)-one 2-amino-9-(4-methoxybenzyl)-7H-purin-8(9H)-one 2-amino-7-cyclopentyl-9-(4-methoxybenzyl)-7H-purin-8(9H)-one 2-butoxy-9-(4-morpholinobenzyl)-7H-purin-8(9H)-one 2-butoxy-9-(4-(piperazin-1-yl)benzyl)-7,9-dihydro-8H-purin-8-one 2-(4-(4-((2-butoxy-8-oxo-7H-purin-9(8H)-yl)methyl)phenyl)piperazin-1-yl)acetamide 2-butoxy-9-(4-((1-methylpiperidin-4-yl)amino)benzyl)-7H-purin-8(9H)-one 2-butoxy-9-(4-(4-methylpiperazin-1-yl)benzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-(4-isopropylpiperazin-1-yl)benzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7,9-dihydro-8H-purin-8- one 2-butoxy-9-(4-(pyrrolidin-1-yl)benzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-(piperidin-1-yl)benzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-cyclohexylbenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-(1-isopropylpiperidin-4-yl)benzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-((6-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)pyridin-3-yl)methyl)-7H-purin- 8(9H)-one 2-butoxy-9-((6-(4-methylpiperazin-1-yl)pyridin-3-yl)methyl)-7H-purin-8(9H)-one 9-(3-(2-oxa-5-azabicyclo[2.2.1]heptan-5-yl)propyl)-2-butoxy-7H-purin-8(9H)-one 2-butoxy-9-(3-(piperazin-1-yl)propyl)-7H-purin-8(9H)-one 2-butoxy-9-(3-(2,6-dimethylmorpholino)propyl)-7H-purin-8(9H)-one 2-butoxy-9-(3-(3,5-dimethylmorpholino)propyl)-7H-purin-8(9H)-one 9-(3-(6-oxa-3-azabicyclo[3.1.1]heptan-3-yl)propyl)-2-butoxy-7H-purin-8(9H)-one 9-(3-(3-oxa-6-azabicyclo[3.1.1]heptan-6-yl)propyl)-2-butoxy-7H-purin-8(9H)-one 4-(3-(2-butoxy-8-oxo-7H-purin-9(8H)-yl)propyl)morpholin-2-one 4-(3-(2-butoxy-8-oxo-7H-purin-9(8H)-yl)propyl)morpholin-3-one 2-butoxy-9-(3-(3-methylmorpholino)propyl)-7H-purin-8(9H)-one 2-butoxy-9-(3-(2-methylmorpholino)propyl)-7H-purin-8(9H)-one 4-(3-(2-butoxy-8-oxo-7H-purin-9(8H)-yl)propyl)morpholine-2-carbonitrile 9-(3-(8-oxa-3-azabicyclo[3.2.1]octan-3-yl)propyl)-2-butoxy-7H-purin-8(9H)-one 4-(3-(2-butoxy-8-oxo-7H-purin-9(8H)-yl)propyl)-6-methylmorpholin-2-one 2-butoxy-9-(3-(2,2-dimethylmorpholino)propyl)-7H-purin-8(9H)-one 2-butoxy-9-(3-(2,5-dimethylmorpholino)propyl)-7H-purin-8(9H)-one 4-(3-(2-butoxy-8-oxo-7H-purin-9(8H)-yl)propyl)-7-oxa-4-azaspiro[2.5]octan-6-one 2-butoxy-9-(2-morpholinoethyl)-7H-purin-8(9H)-one 7-(1-(2-aminoethyl)pyrrolidin-3-yl)-2-(butylamino)-9-(4-methoxybenzyl)-7,9-dihydro-8H- purin-8-one 2-(butylamino)-9-(4-methoxybenzyl)-7-(1-(2-(methylamino)ethyl)pyrrolidin-3-yl)-7,9- dihydro-8H-purin-8-one 2-(butylamino)-7-(1-(2-(dimethylamino)ethyl)pyrrolidin-3-yl)-9-(4-methoxybenzyl)-7,9- dihydro-8H-purin-8-one 7-(1-(2-(3-aminopyrrolidin-1-yl)ethyl)pyrrolidin-3-yl)-2-(butylamino)-9-(4-methoxybenzyl)- 7,9-dihydro-8H-purin-8-one 2-(3-(2-(butylamino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7-yl)pyrrolidin-1- yl)acetamide 2-(3-(2-(butylamino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7-yl)pyrrolidin-1- yl)-N-methylacetamide 2-(3-(2-(butylamino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7-yl)pyrrolidin-1- yl)-N,N-dimethylacetamide 2-(3-(2-(dimethylamino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7-yl)pyrrolidin- 1-yl)-N,N-dimethylacetamide 2-(3-(2-((3-(1H-imidazol-1-yl)propyl)amino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H- purin-7-yl)pyrrolidin-1-yl)-N,N-dimethylacetamide 2-(3-(9-(4-methoxybenzyl)-2-((2-(4-methylpiperazin-1-yl)ethyl)amino)-8-oxo-8,9-dihydro- 7H-purin-7-yl)pyrrolidin-1-yl)-N,N-dimethylacetamide 2-(3-(9-(4-methoxybenzyl)-2-((3-(4-methylpiperazin-1-yl)propyl)amino)-8-oxo-8,9-dihydro- 7H-purin-7-yl)pyrrolidin-1-yl)-N,N-dimethylacetamide 2-(3-(2-((4-fluorobenzyl)amino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7- yl)pyrrolidin-1-yl)-N,N-dimethylacetamide 2-(3-(9-(4-methoxybenzyl)-8-oxo-2-((4-(trifluoromethyl)phenyl)amino)-8,9-dihydro-7H- purin-7-yl)pyrrolidin-1-yl)-N,N-dimethylacetamide 2-(3-(2-((4-trifluorophenyl)amino)-9-methyl-8-oxo-8,9-dihydro-7H-purin-7-yl)pyrrolidin-1- yl)-N,N-dimethylacetamide N,N-dimethyl-2-(3-(2-((2-(4-methylpiperazin-1-yl)ethyl)amino)-8-oxo-8,9-dihydro-7H-purin- 7-yl)pyrrolidin-1-yl)acetamide 2-(3-(9-isopropyl-2-((2-(4-methylpiperazin-1-yl)ethyl)amino)-8-oxo-8,9-dihydro-7H-purin-7- yl)pyrrolidin-1-yl)-N,N-dimethylacetamide In another embodiment of the invention wherein compounds may be in a free form or in pharmaceutically acceptable form. Another objective of the present invention is to provide compounds of general formula I without C-6 primary amino (-NH2) and replace it with a hydrogen (H). In another embodiment of the invention wherein compounds may be beneficial for the treatment of different immunosuppressive diseases where inhibition of TLR7 plays a critical role. In another embodiment of the invention wherein compounds may be beneficial for the treatment of different auto-immune diseases where activation of TLR7 plays a critical role. In another embodiment of the invention wherein compounds may be useful in activating TLR7 mediated immune-stimulatory signalling comprising contacting a cell expressing a TLR7 with effective amount of these compounds. In another embodiment of the invention wherein compounds may be useful in inhibiting TLR7 mediated immune-stimulatory signalling comprising contacting a cell expressing a TLR7 with effective amount of these compounds. In another embodiment of the invention wherein compounds may be beneficial for the treatment of different immunosuppressive diseases where inhibition of TLR9 plays a critical role. In another embodiment of the invention wherein compounds may be beneficial for the treatment of different auto-immune diseases where activation of TLR9 plays a critical role. In another embodiment of the invention wherein compounds may be useful in activating TLR9 mediated immune-stimulatory signalling comprising contacting a cell expressing a TLR9 with effective amount of these compounds. In another embodiment of the invention wherein compounds may be useful in inhibiting TLR9 mediated immune-stimulatory signalling comprising contacting a cell expressing a TLR9 with effective amount of these compounds. Yet another embodiment of the invention wherein compounds having structure I, are prepared by the process wherein the steps comprising: (i) ethyl 2,4-dichloropyrimidine-5-carboxylate (1) was taken in dry acetonitrlie and Et3N was added to it. Requisite amine such as 3-morpholinopropan-1-amine, 3-(piperidin-1-yl)propan-1- amine, 3-(4-ethylpiperazin-1-yl)propan-1-amine, phenylmethanamine, (4- methoxyphenyl)methanamine, 4-methoxybenzyl amine, 4-aminobenzyl amine, (4- bromophenyl)methanamine, (4-(dimethylamino)phenyl)methanamine, tert-butyl 4- (aminomethyl)benzylcarbamate, (6-methoxypyridin-3-yl)methanamine, tert-butyl 4- aminocyclohexanecarboxylate was added to the reaction mixture to obtain the compound 2, 5, 8, 11, 14, 18, 21, 24, 30, 40, 180. (ii) Sodium tert-butoxide was added portionwise to the protic solvent nBuOH. Compound 2, 5, 8, 11, 14, 18, 21, 24, 30, 40, 180 obtained in step (i) was added to the solution to obtain the compound 3, 6, 9, 12, 15, 19, 22, 25, 31, 41, 181 respectively. (iii) Compound 3, 6, 9, 12, 15, 19, 22, 25, 31, 41, 181 obtained in step (ii), and diphenylphosphoryl azide was taken in dry DMA. Et₃N was added to the solution and refluxed for 12 hours to obtain the compound 4, 7, 10, 13, 16, 20, 23, 26, 32, 42, 183 respectively. (iv) Compound 16 obtained in step (iii) was taken in dry DCM. BBr₃ was added to the solution dropwise at 0 °C and the reaction mixture was stirred for 30 minutes at 0 °C to obtain the product 17 as white solid. (v) Compound 17 obtained in step (iv) was taken in dry THF and boc-anhydride was added to the solution at 0 °C. The reaction mixture was then stirred for 30 minutes to get the compound 27 as white solid. (vi) Compound 27 obtained in step (v) was taken in acetonitrile and Et₃N was added to it. N- (2-bromoethyl)phthalimide was added to the reaction mixture and stirred for 2 hours at room temperature to obtain the compound 28 as white solid. (vii) Compound 28 obtained in step (vi) was treated with NH₂-NH₂. H₂O in EtOH and refluxed for 3 hours to obtain the compound 29 as gummy liquid. (viii) Compound 32 obtained in step (iii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 33 as brown solid. (ix) Compound 27 obtained in step (v) was taken in dry DMF and K₂CO₃ was added to it. 1- bromo-2-chloro ethane was added to the reaction mixture and stirred for 2 hours at 50 °C to obtain the compound 34 as white solid. (x) Compound 34 obtained in step (ix) was taken in dry DMF and K₂CO₃ was added to it.2- methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, pyrrolidine, dimethylamine, tert-butyl piperazine-1-carboxylate, morpholine was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 35, 36, 37, 38, 39 respectively. (x) Compound 4 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. 1- bromobutane, 2-bromoethanol, 3-bromopropanol, N-(3-bromopropyl)phthalimide, allyl bromide, benzyl bromide was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 43, 44, 45, 46, 48, 49 respectively. (xi) Compound 46 obtained in step (x) was treated with NH2-NH2. H2O in EtOH and refluxed for 3 hours to obtain the compound 47 as gummy liquid. (xii) Compound 13 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it.1- bromobutane, allyl bromide, 2-bromoethanol, 3-bromopropanol was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 50, 51, 52, 53 respectively. (xiii) Compound 16 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it.1- bromobutane, allyl bromide, 2-bromoethanol, 3-bromopropanol, (4S)-4-(bromomethyl)-2,2- dimethyl-1,3-dioxolane, (4R)-4-(bromomethyl)-2,2-dimethyl-1,3-dioxolane,N-(3- bromopropyl)phthalimide, 1-bromo-3-chloro propane, N-(2-bromoethyl)phthalimide, α,α'- dibromo-p-xylene, bromocyclopentane, 2-bromopropane, 4-fluorobenzyl bromide, 3- (bromomethyl)-2-chloro-5-fluoropyridine was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 54, 55, 56, 57, 58, 60, 62, 64, 66, 68, 70, 73, 74, 75 respectively. (xiv) Compound 58 obtained in step (xiii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 59 as gummy liquid. (xv) Compound 60 obtained in step (xiii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 61 as gummy liquid. (xvi) Compound 62 obtained in step (xiii) was treated with NH₂-NH₂. H₂O in EtOH and refluxed for 3 hours to obtain the compound 63 as gummy liquid. (xvii) Compound 64 obtained in step (xiii) was taken in dry DMF and K₂CO₃ was added to it. Morpholine was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 65. (xviii) Compound 66 obtained in step (xiii) was treated with NH2-NH2. H2O in EtOH and refluxed for 3 hours to obtain the compound 67 as gummy liquid. (xix) Compound 68 obtained in step (xiii) was taken in dry DMF and K₂CO₃ was added to it. Morpholine was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 69. (xx) Compound 16 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. tert- butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 71. (xxi) Compound 71 obtained in step (xx) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 72 as gummy liquid. (xxii) Compound 42 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. bromocyclopentane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 76. (xxiii) Compound 42 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. tert-butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 77. (xxiv) Compound 77 obtained in step (xxiii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 78 as gummy liquid. (xxv) Compound 32 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it.1- bromobutane, bromocyclopentane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 79, 81 respectively. (xxvi) Compound 79 obtained in step (xxv) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 80 as gummy liquid. (xxvii) Compound 81 obtained in step (xxv) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 82 as gummy liquid. (xxviii) In a pressure tube, dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. n-butylamine was added to the solution with continuous N₂ purging and the followed by the addition of NaO^tBu. Finally compound 2 obtained from step (i) was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 83 as brown solid. (xxix) Compound 14, 40, 30 obtained in step (i) was taken in dry acetonitrile and Et₃N was added to it. n-butylamine was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 86, 89, 92 respectively. (xxx) A solution of KOH in water was added to a stirred solution of Compound 83,86, 89, 92 in THF (7.5 ml). The reaction mixture was stirred at 140 °C for 8 hours to obtain the compound 84, 87, 90, 93 respectively. (xxxi) Compound 84, 87, 90, 93 obtained in step (xxx), and diphenylphosphoryl azide was taken in dry DMA. Et₃N was added to the solution and refluxed for 12 hours to obtain the compound 4, 85, 88, 91, 94 respectively. (xxxii) Compound 94 obtained in step (xxxi) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 95 as brown solid. (xxxiii) Compound 94 obtained in step (xxxii) was taken in dry DMF and K₂CO₃ was added to it. bromocyclopentane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 96. (xxxiv) Compound 96 obtained in step (xxxiii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 97 as gummy liquid. (xxxv) Compound 94 obtained in step (xxxi) was taken in dry DMF and K₂CO₃ was added to it. tert-butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 98. (xxxvi) Compound 98 obtained in step (xxxv) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 99 as gummy liquid. (xxxvii) Compound 88 obtained in step (xxxi) was taken in dry DMF and K₂CO₃ was added to it. 1-bromobutane, bromocyclopentane, 2-bromopropane, 4-fluorobenzyl bromide, 3- (bromomethyl)-2-chloro-5-fluoropyridine, N-(3-bromopropyl)phthalimide, N-(2- bromoethyl)phthalimide, α,α'-dibromo-p-xylene, 1-Bromo-2-chloro ethane, 1-bromo-3-chloro propane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 100, 101, 104, 105, 106, 107, 109, 111, 113, 116 respectively. (xxxviii) Compound 88 obtained in step (xxxi) was taken in dry DMF and K₂CO₃ was added to it. tert-butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 102. (xxxix) Compound 102 obtained in step (xxxviii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 103 as gummy liquid. (XL) Compound 107 or Compound 109 was treated with NH₂-NH₂. H₂O in EtOH and refluxed for 3 hours to obtain the compound 108 or 110 respectively as gummy liquid. (XLI) Compound 111 obtained in step (xxxvii) was taken in dry DMF and K₂CO₃ was added to it. Pyrrolidine was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 112. (XLII) Compound 113 obtained in step (xxxvii) was taken in dry DMF and K₂CO₃ was added to it. Dimethylamine and methylamine were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 114 and 115 respectively as gummy liquid. (XLIII) Compound 113 obtained in step (xxxvii) was taken in dry DMF and K₂CO₃ was added to it. Dimethylamine and methylamine were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 114 and 115 respectively as gummy liquid. (XLIV) Compound 113 obtained in step (xxxvii) was taken in dry DMF and K₂CO₃ was added to it. Pyrrolidine and 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 117 and 118 respectively as gummy liquid. (XLV) Compound 101 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 119 as brown solid. (XLVI) Compound119 obtained in step (XLV) was taken in dry DMF and K₂CO₃ was added to it. 3-methoxybenzyl bromide, 4-bromobenzyl bromide, 1-(bromomethyl)naphthalene, 4- bromomethylbiphenyl, α,α'-dibromo-p-xylene, was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 120, 121, 122, 123, 128 respectively. (xlvii) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, tert-butyl piperazine-1-carboxylate, piperidine depending on the requirement of desired product were added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu. Finally compound 121 obtained from step (XLVI) was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 124, 125, 127 respectively. (xlviii) Compound 125 obtained from step (xlvii) was taken in 2 ml of DCM. TFA was added to the solution at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 126 respectively. (xlix) Compound 128 obtained in step (xlix) was taken in dry DMF and K₂CO₃ was added to it. Pyrrolidine and 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 129 respectively as gummy liquid. (l) Compound 118 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 130. (li) Compound 130 obtained in step (l) was taken in dry DMF and K₂CO₃ was added to it. 3- methoxybenzyl bromide, 4-bromobenzyl Bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 131 respectively. (lii) Compound 14 obtained in step (i) was taken in dry acetonitrile and Et₃N was added to it. n-propylamine, ethylamine, 3-(pyrrolidin-1-yl)propan-1-amine, (4- fluorophenyl)methanamine, Boc-amide were added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 132, 144, 169, 175 and 198 respectively. (liii) A solution of KOH in water was added to a stirred solution of Compound 132, 144, 169 and 175 in THF (7.5 ml). The reaction mixture was stirred at 140 °C for 8 hours to obtain the compound 133, 145, 170, 176 and 199 respectively. (liv) Compound 133, 145, 170 and 176 obtained in step (liii), and diphenylphosphoryl azide was taken in dry DMA. Et3N was added to the solution and refluxed for 12 hours to obtain the compound 134, 146, 171, 177 and 200 respectively. (lv) Compound 134 obtained in step (l) was taken in dry DMF and K₂CO₃ was added to it. bromocyclopentane, 1-bromo-3-chloro propane were added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 135 or 136 respectively. (xlvi) Compound 136 obtained in step (lv) was taken in dry DMF and K₂CO₃ was added to it. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 137. (xlvii) Compound 135 or 137 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 138 or 140. (xlviii) Compound 138 obtained in step (xlvii) was taken in dry DMF and K₂CO₃ was added to it.4-bromobenzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 139. (xlix) Compound 138 obtained in step (xlvii) was taken in dry DMF and K₂CO₃ was added to it. 4-bromobenzyl bromide, 4-(trifluromethyl)benzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 141 and 142 respectively. (lx) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, were added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu. Finally compound 141 obtained from step (xlix) was added to the pre- stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 143. (lxi) Compound 146 obtained in step (liv) was taken in dry DMF and K₂CO₃ was added to it. bromocyclopentane, 1-bromo-3-chloro propane were added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 147 or 148 respectively. (lxii) Compound 148 obtained in step (lxi) was taken in dry DMF and K₂CO₃ was added to it. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 149. (lxiii) Compound 147or 149 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 150 or 152. (lxiv) Compound 150 obtained in step (lxiii) was taken in dry DMF and K₂CO₃ was added to it.4-bromobenzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 151. (lxv) Compound 152 obtained in step (lxiii) was taken in dry DMF and K₂CO₃ was added to it. 4-bromobenzyl bromide, 4-(trifluromethyl)benzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 153and 154 respectively. (lxvi) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, N,N-dimethylpiperidin-4-amine were added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu. Finally compound 153 obtained from step (lxv) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 155 and 156 respectively. (lxvii) Compound 14 obtained in step (i) was taken in dry nBuOH and NaOEt was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 157. (lxviii) Compound 157 obtained in step (lxvii), and diphenylphosphoryl azide was taken in dry DMA. Et3N was added to the solution and refluxed for 12 hours to obtain the compound 158. (lxix) Compound 158 obtained in step (lxviii) was taken in dry DMF and K₂CO₃ was added to it. Bromocyclopentane and 1-bromo-3-chloro propane were added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 159 and 161 respectively. (lxx) Compound 159 obtained in step (lxix) was taken in dry DMF and K₂CO₃ was added to it. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 85 °C to obtain the compound 160. (lxxi) Compound 161 or 160 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 162 or 164. (lxxii) Compound 162 or 164 obtained in step (lxxi) was taken in dry DMF and K₂CO₃ was added to it.4-bromobenzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 163 and 165 respectively. (lxxiii) Compound 164 obtained in step (lxxii) was taken in dry DMF and K₂CO₃ was added to it.4-(trifluromethyl)benzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 166. (lxxiv) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, N,N-dimethylpiperidin-4-amine were added to the solution with continuous N₂ purging and the followed by the addition of NaO^tBu. Finally compound 165 obtained from step (lxxii) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 167 and 168 respectively. (lxxv) Compound 171 obtained in step (liv) was taken in dry DMF and K₂CO₃ was added to it. 1-bromobutane, Bromocyclopentane, 3-(bromomethyl)-5-fluoropyridine was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 172, 173 and 174 respectively. (lxxvi) Compound 177 obtained in step (liv) was taken in dry DMF and K₂CO₃ was added to it. 1-bromobutane, Bromocyclopentane was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 178 and 179 respectively. (lxxvii) Compound 183 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. Bromocyclopentane was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 184. (lxxviii) Compound 184 was treated with TFA in DCM at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 185. (lxxix) Compound 185 obtained in step (lxxviii) was taken in dry DMF and K₂CO₃ was added to it. 1-(bromomethyl)-4-methoxybenzene, 1-(bromomethyl)-4-fluorobenzene, 1- (bromomethyl)-3-fluorobenzene, 1-(bromomethyl)-2-fluorobenzene, 1- (bromomethyl)naphthalene, 5-(bromomethyl)-2-fluoropyridine, 3-(bromomethyl)-5- fluoropyridine, 1-(bromomethyl)-4-(trifluoromethyl)benzene was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 186, 187, 188, 189, 190, 191, 192 and 193 respectively. (lxxix) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Palladium acetate(0) and X-Phos were added to the toluene one by one and purged for 5-10 minutes. 1-bromo-4-fluorobenzene was added to the solution with continuous N2 purging and the followed by the addition of K3PO4. Finally compound 185 obtained from step (lxxviii) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 194. (lxxx) Compound 185 obtained in step (lxxviii) was taken in dry DCM and Et3N was added to it. 4-fluorobenzoyl chloride, acetyl chloride, isobutyryl chloride was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 195, 196 and 197 respectively. (lxxxi) Compound 200 was treated with 4(N) HCl in dioxane at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 201. (lxxxii) Compound 201 obtained in step (lxxxi) was taken in dry DMF and K₂CO₃ was added to it. Bromocyclopentane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 202. (lxxxiii) In a pressure tube, dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Palladium acetate(0) and X-Phos were added to the toluene one by one and purged for 5-10 minutes. Morpholine, N-bocpiperazine, 1-methylpiperidin-4-amine, 1- methylpiperazine, 1-isopropylpiperazine, 2-methyl-2,5-diazabicyclo[2.2.1]heptane, pyrrolidine, piperidine was added to the solution with continuous N₂ purging and the followed by the addition of K₃PO₄ to attain different products. Finally compound 23 obtained from step (iii) was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 203, 204, 207, 208, 209, 210, 211, 212. (lxxxiv) Compound 204 was treated with 4(N) HCl in dioxane at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 205. (lxxxv) Compound 205 obtained in step (lxxxiv) was taken in dry DMF and K₂CO₃ was added to it.2-bromoacetamide was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 206. (lxxxvi) In a pressure tube, dry dioxane was taken and sonicated with continuous N2 purging for 15 minutes. Tetrakis(triphenylphosphine)palladium(0) and cyclohexylboronic acid or (1- (tert-butoxycarbonyl)piperidin-4-yl)boronic acid , were added to the dioxane one by one and purged for 5-10 minutes for different reaction. K3PO4 was added and purged for another 5 minutes. Finally compound 23 obtained from step (iii) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 213, 214. (lxxxvii) Compound 214 obtained in step (lxxxvi) was taken in dry DMF and Et3N was added to it. Fmoc-Cl was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 215. (lxxxviii) Compound 215 was treated with 4(N) HCl in dioxane at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 216. (lxxxix) Compound 216 obtained in step (lxxxiv) was taken in dry DMF and K₂CO₃ was added to it.2-iodopropanewas added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 217. (lxxxx) In a pressure tube, dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Palladium acetate(0) and X-Phos were added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane, 1-methylpiperazine were added to the solution with continuous N2 purging and the followed by the addition of K3PO4 to attain different products. Finally 9-((6-bromopyridin-3-yl)methyl)-2-butoxy-7,9-dihydro-8H- purin-8-one was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 218 and 219. (lxxxxi) Compound 16 obtained in step (iii) was taken in dry DMF and Et3N was added to it. Fmoc-Cl was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 220. (lxxxxii) Compound 220 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 3 hours at room temperature to obtain the compound 221. (lxxxxiii) Compound 221 obtained in step (lxxxxii) was taken in dry DMF and Et₃N was added to it. 1-bromo-3-chloro propane and 1-bromo-2-chloro ethane were added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 222 and 239. (lxxxxiv) Compound 222 obtained in step (lxxxxiii) was taken in dry DMF and K₂CO₃ was added to it. 2-oxa-5-azabicyclo[2.2.1]heptane, tert-butyl piperazine-1-carboxylate, 2,6- dimethylmorpholine, 3,5-dimethylmorpholine, 6-oxa-3-azabicyclo[3.1.1]heptane, 3-oxa-6- azabicyclo[3.1.1]heptane, morpholin-2-one, morpholin-3-one, 3-methylmorpholine, 2- methylmorpholine, morpholine-2-carbonitrile, 8-oxa-3-azabicyclo[3.2.1]octane, 6- methylmorpholin-2-one, 2,2-dimethylmorpholine, 2-methylmorpholine, 7-oxa-4- azaspiro[2.5]octan-6-one was added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237 and 238. (lxxxxv) Compound 239 obtained in step (lxxxxiii) was taken in dry DMF and K₂CO₃ was added to it. Morpholine was added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 240. (lxxxxvi) Compound 107 obtained in step () was taken in dry DMF and K₂CO₃ was added to it. 2-bromoethan-1-amine, 2-bromo-N-methylethan-1-amine, 2-bromo-N,N-dimethylethan-1- amine, 1-(2-bromoethyl)pyrrolidin-3-amine, 2-bromoacetamide, 2-bromo-N-methylacetamide, 2-bromo-N,N-dimethylacetamide were added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 241, 242, 243, 244, 245, 246, 247 respectively. (lxxxxvii) Lithium hydroxide was added portionwise to the THF and H2O solution. Compound 14 obtained in step (i) was added to the solution to obtain the compound 248. (lxxxxviii) Compound 248 obtained in step (lxxxxvii), and diphenylphosphoryl azide was taken in dry DMA. Et3N was added to the solution and refluxed for 12 hours to obtain the compound 249. (lxxxxix) Compound 249 obtained in step (lxxxxviii) was taken in dry DMF and K₂CO₃ was added to it. tert-butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 250. (lxxxxx) Compound 250 was treated with 4(N) HCl in dioxane at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 251. (lxxxxxi) Compound 251 was taken in dry DMF and K₂CO₃ was added to it. 2-bromo-N,N- dimethylacetamide was added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 252. (lxxxxxii) Compound 252 was taken in dry Dioxane and K₂CO₃ was added to it. Dimethylamine, 3-(1H-imidazol-1-yl)propan-1-amine, 2-(4-methylpiperazin-1-yl)ethan-1- amine, 3-(4-methylpiperazin-1-yl)propan-1-amine, (4-fluorophenyl)methanamine were added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 253, 254, 255, 256, 257 respectively. (lxxxxxiii) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Palladium acetate(0) and X-Phos were added to the toluene one by one and purged for 5-10 minutes.4-(trifluoromethyl)aniline was added to the solution with continuous N₂ purging and the followed by the addition of K₃PO₄ to attain different products. Finally compound 107 was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 258. (lxxxxxiv) Compound 258, 255 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 3 hours at room temperature to obtain the compound 259 and 261 respectively. (lxxxxxv) Compound 259 and 261 obtained in step (lxxxxxiv) was taken in dry DMF and K₂CO₃ was added to it. Methyl iodide and 2-iodopropane were added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 261 and 262 respectively. Further embodiment of the invention wherein the compounds can be used for the preparation of pharmaceutical composition comprising a compound as claimed in claim (I) optionally along with pharmaceutically – acceptable excipients. In another embodiment according to this aspect of the invention, a screening method of affecting TLR mediated signalling in response to a TLR ligand is provided, which involves detecting TLR7 and TLR9 antagonism of effective amount of a compound of general Formula (I) using a reporter cell line that reports nuclear factor kappa B expression downstream of TLR9 signalling. In another embodiment according to this aspect of the invention, said compounds with formula (I) described by the present invention increase or partially modulate immune response mediated through TLR7 and TLR9. In another embodiment according to this aspect of the invention, compounds of general formula (I) is useful whenever it is desirable to alter TLR7/9 mediated signalling in response to a suitable TLR ligand or TLR signalling agonist. In another embodiment according to this aspect of the invention, it is believed that the said compounds with formula (I) can be useful to activate an immune system response in a subject associated with suppressed immune condition. In another embodiment according to this aspect of the invention, it is believed that the said compounds with formula (I) can be useful to act as antiviral or antitumor vaccine adjuvants. In another embodiment according to this aspect of the invention, it is believed that the said compounds with formula (I) can be useful to inhibit an immune stimulatory nucleic acid associated response in a subject. In another embodiment according to this aspect of the invention, it is believed that the said compounds with general formula (I) that can modulate autoreactive inflammation in different autoimmune diseases where aberrant TLR7 and/or TLR9 activation is implicated for such diseases. In another embodiment according to this aspect of the invention, it is believed that the said compounds with general formula (I) can be used in a number of clinical applications, including as pharmaceutical agents and methods for treating conditions involving unwanted immune suppression due to reduced TLR7 and/or TLR9 activation. In another embodiment according to this aspect of the invention, it is believed that the said compounds with general formula (I) can be used in a number of clinical applications, including as pharmaceutical agents and methods for treating conditions involving unwanted immune activity due to TLR7 and/or TLR9 activation. In another embodiment according to this aspect of the invention, the said compounds with formula (I) is believed to affect TLR7 and TLR directly and thus affect TLR-bearing cells, such as antigen-presenting cells (APCs). BRIEF DESCRIPTION OF DRAWING The invention has other advantages and features which will be more readily apparent from the following detailed description of the invention and the appended claims, when taken in conjunction with the accompanying drawings which: in Fig 1, Reporter assay for TLR7 agonism using a HEK-Blue TLR7 cell line expressing a TLR7-responsive, NF-κB-inducible SEAP. The graphs denote dose-dependent inhibition of TLR7 activation in a HEK-Blue-hTLR7 reporter cell line in the presence of different doses (1, 3, 5, 10, 30 µM) of the compound with general formula (I) which is represented in terms of increase in SEAP activity. Data shown are mean of triplicate wells ± SD. Fig 2, Reporter assay for TLR7 antagonism using a HEK-Blue TLR7 cell line expressing a TLR7-responsive, NF-κB-inducible SEAP. The graphs denote dose-dependent inhibition of TLR7 activation in a HEK-Blue-hTLR7 reporter cell line in the presence of different doses (1, 3, 5, 10, 30 µM) of the compound with general formula (I), which is represented in terms of decrease in SEAP activity. Data shown are mean of triplicate wells ± SD. Fig 3, Reporter assay for TLR9 agonism using a HEK-Blue TLR9 cell line expressing a TLR9-responsive, NF-κB-inducible SEAP. The graphs denote dose-dependent inhibition of TLR9 activation in a HEK-Blue-hTLR9 reporter cell line in the presence of different doses (1, 3, 5, 10, 30 µM) of the compound with general formula (I), which is represented in terms of increase in SEAP activity. Data shown are mean of triplicate wells ± SD. Fig 4, Reporter assay for TLR9 antagonism using a HEK-Blue TLR9 cell line expressing a TLR9-responsive, NF-κB-inducible SEAP. The graphs denote dose-dependent inhibition of TLR9 activation in a HEK-Blue-hTLR9 reporter cell line in the presence of different doses (0.25, 0.5, 1, 3, 5 µM) of the compound with general formula (I), which is represented in terms of decrease in SEAP activity. Data shown are mean of triplicate wells ± SD. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the compound represented by following structure I or a pharmaceutically acceptable salt thereof: Structure 1 Wherein R₁ is independently selected from groups referred to as follows:

R2 is independently selected from groups referred to as follows: R₃ is independently selected from groups referred to as follows:

R4 is independently selected as H. The compound of present invention has the Structure I consisting hydrogen (H) at C-6 is depicted in the table below: Structure 1 The general process of preparation: (i) ethyl 2,4-dichloropyrimidine-5-carboxylate (1) was taken in dry acetonitrlie and Et3N was added to it. Requisite amine such as 3-morpholinopropan-1-amine, 3-(piperidin-1-yl)propan-1- amine, 3-(4-ethylpiperazin-1-yl)propan-1-amine, phenylmethanamine, (4- methoxyphenyl)methanamine, 4-methoxybenzyl amine, 4-aminobenzyl amine, (4- bromophenyl)methanamine, (4-(dimethylamino)phenyl)methanamine, tert-butyl 4- (aminomethyl)benzylcarbamate, (6-methoxypyridin-3-yl)methanamine, tert-butyl 4- aminocyclohexanecarboxylate was added to the reaction mixture to obtain the compound 2, 5, 8, 11, 14, 18, 21, 24, 30, 40, 180. (ii) Sodium tert-butoxide was added portionwise to the protic solvent nBuOH. Compound 2, 5, 8, 11, 14, 18, 21, 24, 30, 40, 180 obtained in step (i) was added to the solution to obtain the compound 3, 6, 9, 12, 15, 19, 22, 25, 31, 41, 181 respectively. (iii) Compound 3, 6, 9, 12, 15, 19, 22, 25, 31, 41, 181 obtained in step (ii), anddiphenylphosphoryl azide was taken in dry DMA. Et₃N was added to the solution and refluxed for 12 hours to obtain the compound 4, 7, 10, 13, 16, 20, 23, 26, 32, 42, 183 respectively. (iv) Compound 16 obtained in step (iii) was taken in dry DCM. BBr3 was added to the solution dropwise at 0 °C and the reaction mixture was stirred for 30 minutes at 0 °C to obtain the product 17 as white solid. (v) Compound 17 obtained in step (iv) was taken in dry THF and boc-anhydride was added to the solution at 0 °C. The reaction mixture was then stirred for 30 minutes to get the compound 27 as white solid. (vi) Compound 27 obtained in step (v) was taken in acetonitrile and Et3N was added to it. N- (2-bromoethyl)phthalimide was added to the reaction mixture and stirred for 2 hours at room temperature to obtain the compound 28 as white solid. (vii) Compound 28 obtained in step (vi) was treated with NH2-NH2. H2O in EtOH and refluxed for 3 hours to obtain the compound 29 as gummy liquid. (viii) Compound 32 obtained in step (iii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 33 as brown solid. (ix) Compound 27 obtained in step (v) was taken in dry DMF and K₂CO₃ was added to it.1- bromo-2-chloro ethane was added to the reaction mixture and stirred for 2 hours at 50 °C to obtain the compound 34as white solid. (x) Compound 34 obtained in step (ix) was taken in dry DMF and K₂CO₃ was added to it.2- methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, pyrrolidine, dimethylamine, tert-butyl piperazine-1-carboxylate, morpholine was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 35, 36, 37, 38, 39 respectively. (x) Compound 4 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. 1- bromobutane, 2-bromoethanol, 3-bromopropanol, N-(3-bromopropyl)phthalimide, allyl bromide, benzyl bromide was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 43, 44, 45, 46, 48, 49 respectively. (xi) Compound 46 obtained in step (x) was treated with NH2-NH2. H2O in EtOH and refluxed for 3 hours to obtain the compound 47 as gummy liquid. (xii) Compound 13 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it.1- bromobutane, allyl bromide, 2-bromoethanol, 3-bromopropanol was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 50, 51, 52, 53 respectively. (xiii) Compound 16 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it.1- bromobutane, allyl bromide, 2-bromoethanol, 3-bromopropanol, (4S)-4-(bromomethyl)-2,2- dimethyl-1,3-dioxolane, (4R)-4-(bromomethyl)-2,2-dimethyl-1,3-dioxolane, N-(3- bromopropyl)phthalimide, 1-bromo-3-chloro propane, N-(2-bromoethyl)phthalimide, α,α'- dibromo-p-xylene, bromocyclopentane, 2-bromopropane, 4-fluorobenzyl bromide, 3- (bromomethyl)-2-chloro-5-fluoropyridine was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 54, 55, 56, 57, 58, 60, 62, 64, 66, 68, 70, 73, 74, 75 respectively. (xiv) Compound 58 obtained in step (xiii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 59 as gummy liquid. (xv) Compound 60 obtained in step (xiii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 61 as gummy liquid. (xvi) Compound 62 obtained in step (xiii) was treated with NH₂-NH₂. H₂O in EtOH and refluxed for 3 hours to obtain the compound 63 as gummy liquid. (xvii) Compound 64 obtained in step (xiii) was taken in dry DMF and K₂CO₃ was added to it. Morpholine was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 65. (xviii) Compound 66 obtained in step (xiii) was treated with NH2-NH2. H2O in EtOH and refluxed for 3 hours to obtain the compound 67 as gummy liquid. (xix) Compound 68 obtained in step (xiii) was taken in dry DMF and K₂CO₃ was added to it. Morpholine was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 69. (xx) Compound 16 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. tert- butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 71. (xxi) Compound 71 obtained in step (xx) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 72 as gummy liquid. (xxii) Compound 42 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. bromocyclopentane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 76. (xxiii) Compound 42 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. tert-butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 77. (xxiv) Compound 77 obtained in step (xxiii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 78 as gummy liquid. (xxv) Compound 32 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it.1- bromobutane, bromocyclopentane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 79, 81 respectively. (xxvi) Compound 79 obtained in step (xxv) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 80 as gummy liquid. (xxvii) Compound 81 obtained in step (xxv) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 82 as gummy liquid. (xxviii) In a pressure tube, dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. n-butylamine was added to the solution with continuous N₂ purging and the followed by the addition of NaO^tBu. Finally compound 2 obtained from step (i) was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 83 as brown solid. (xxix) Compound 14, 40, 30 obtained in step (i) was taken in dry acetonitrile and Et₃N was added to it. n-butylamine was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 86, 89, 92 respectively. (xxx) A solution of KOH in water was added to a stirred solution of Compound 83,86, 89, 92 in THF (7.5 ml). The reaction mixture was stirred at 140 °C for 8 hours to obtain the compound 84, 87, 90, 93 respectively. (xxxi) Compound 84, 87, 90, 93 obtained in step (xxx), and diphenylphosphoryl azide was taken in dry DMA. Et₃N was added to the solution and refluxed for 12 hours to obtain the compound 4, 85, 88, 91, 94 respectively. (xxxii) Compound 94 obtained in step (xxxi) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 95 as brown solid. (xxxiii) Compound 94 obtained in step (xxxii) was taken in dry DMF and K₂CO₃ was added to it. bromocyclopentane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 96. (xxxiv) Compound 96 obtained in step (xxxiii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 97 as gummy liquid. (xxxv) Compound 94 obtained in step (xxxi) was taken in dry DMF and K₂CO₃ was added to it. tert-butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 98. (xxxvi) Compound 98 obtained in step (xxxv) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 99 as gummy liquid. (xxxvii) Compound 88 obtained in step (xxxi) was taken in dry DMF and K₂CO₃ was added to it. 1-bromobutane, bromocyclopentane, 2-bromopropane, 4-fluorobenzyl bromide, 3- (bromomethyl)-2-chloro-5-fluoropyridine, N-(3-bromopropyl)phthalimide, N-(2- bromoethyl)phthalimide, α,α'-dibromo-p-xylene, 1-Bromo-2-chloro ethane, 1-bromo-3-chloro propane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 100, 101, 104, 105, 106, 107, 109, 111, 113, 116 respectively. (xxxviii) Compound 88 obtained in step (xxxi) was taken in dry DMF and K₂CO₃ was added to it. tert-butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 102. (xxxix) Compound 102 obtained in step (xxxviii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 103 as gummy liquid. (XL) Compound 107 or Compound 109 was treated with NH₂-NH₂. H₂O in EtOH and refluxed for 3 hours to obtain the compound 108 or 110 respectively as gummy liquid. (XLI) Compound 111 obtained in step (xxxvii) was taken in dry DMF and K₂CO₃ was added to it. Pyrrolidine was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 112. (XLII) Compound 113 obtained in step (xxxvii) was taken in dry DMF and K₂CO₃ was added to it. Dimethylamine and methylamine were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 114 and 115 respectively as gummy liquid. (XLIII) Compound 113 obtained in step (xxxvii) was taken in dry DMF and K₂CO₃ was added to it. Dimethylamine and methylamine were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 114 and 115 respectively as gummy liquid. (XLIV) Compound 113 obtained in step (xxxvii) was taken in dry DMF and K₂CO₃ was added to it. Pyrrolidine and 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 117 and 118 respectively as gummy liquid. (XLV) Compound 101 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 119 as brown solid. (XLVI) Compound 119 obtained in step (XLV) was taken in dry DMF and K₂CO₃ was added to it. 3-methoxybenzyl bromide, 4-bromobenzyl bromide, 1-(bromomethyl)naphthalene, 4- bromomethylbiphenyl, α,α'-dibromo-p-xylene, was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 120, 121, 122, 123, 128 respectively. (xlvii) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, tert-butyl piperazine-1-carboxylate, piperidine depending on the requirement of desired product were added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu. Finally compound 121 obtained from step (XLVI) was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 124, 125, 127 respectively. (xlviii) Compound 125 obtained from step (xlvii) was taken in 2 ml of DCM. TFA was added to the solution at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 126 respectively. (xlix) Compound 128 obtained in step (xlix) was taken in dry DMF and K₂CO₃ was added to it. Pyrrolidine and 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 129 respectively as gummy liquid. (l) Compound 118 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 130. (li) Compound 130 obtained in step (l) was taken in dry DMF and K₂CO₃ was added to it. 3- methoxybenzyl bromide, 4-bromobenzyl Bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 131 respectively. (lii) Compound 14 obtained in step (i) was taken in dry acetonitrile and Et3N was added to it. n-propylamine, ethylamine, 3-(pyrrolidin-1-yl)propan-1-amine, (4- fluorophenyl)methanamine, Boc-amide were added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 132, 144, 169, 175 and 198 respectively. (liii) A solution of KOH in water was added to a stirred solution of Compound 132, 144, 169 and 175 in THF (7.5 ml). The reaction mixture was stirred at 140 °C for 8 hours to obtain the compound 133, 145, 170, 176 and 199 respectively. (liv) Compound 133, 145, 170 and 176 obtained in step (liii), and diphenylphosphoryl azide was taken in dry DMA. Et₃N was added to the solution and refluxed for 12 hours to obtain the compound 134, 146, 171, 177 and 200 respectively. (lv) Compound 134 obtained in step (l) was taken in dry DMF and K₂CO₃ was added to it. bromocyclopentane, 1-bromo-3-chloro propane were added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 135 or 136 respectively. (xlvi) Compound 136 obtained in step (lv) was taken in dry DMF and K₂CO₃ was added to it. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 137. (xlvii) Compound 135 or 137 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 138 or 140. (xlviii) Compound 138 obtained in step (xlvii) was taken in dry DMF and K₂CO₃ was added to it.4-bromobenzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 139. (xlix) Compound 138 obtained in step (xlvii) was taken in dry DMF and K₂CO₃ was added to it. 4-bromobenzyl bromide, 4-(trifluromethyl)benzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 141 and 142 respectively. (lx) In a pressure tube, dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, were added to the solution with continuous N₂ purging and the followed by the addition of NaO^tBu. Finally compound 141 obtained from step (xlix) was added to the pre- stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 143. (lxi) Compound 146 obtained in step (liv) was taken in dry DMF and K₂CO₃ was added to it. bromocyclopentane, 1-bromo-3-chloro propane were added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 147or 148 respectively. (lxii) Compound 148 obtained in step (lxi) was taken in dry DMF and K₂CO₃ was added to it. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 149. (lxiii) Compound 147or 149 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 150 or 152. (lxiv) Compound 150 obtained in step (lxiii) was taken in dry DMF and K₂CO₃ was added to it.4-bromobenzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 151. (lxv) Compound 152 obtained in step (lxiii) was taken in dry DMF and K₂CO₃ was added to it. 4-bromobenzyl bromide, 4-(trifluromethyl)benzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 153 and 154 respectively. (lxvi) In a pressure tube, dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, N,N-dimethylpiperidin-4-amine were added to the solution with continuous N₂ purging and the followed by the addition of NaO^tBu. Finally compound 153 obtained from step (lxv) was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 155 and 156 respectively. (lxvii) Compound 14 obtained in step (i) was taken in dry nBuOH and NaOEt was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 157. (lxviii) Compound 157 obtained in step (lxvii), and diphenylphosphoryl azide was taken in dry DMA. Et₃N was added to the solution and refluxed for 12 hours to obtain the compound 158. (lxix) Compound 158 obtained in step (lxviii) was taken in dry DMF and K₂CO₃ was added to it. Bromocyclopentane and 1-bromo-3-chloro propane were added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 159 and 161 respectively. (lxx) Compound 159 obtained in step (lxix) was taken in dry DMF and K₂CO₃ was added to it. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 85 °C to obtain the compound 160. (lxxi) Compound 161 or 160 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 162 or 164. (lxxii) Compound 162 or 164 obtained in step (lxxi) was taken in dry DMF and K₂CO₃ was added to it.4-bromobenzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 163 and 165 respectively. (lxxiii) Compound 164 obtained in step (lxxii) was taken in dry DMF and K₂CO₃ was added to it.4-(trifluromethyl)benzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 166. (lxxiv) In a pressure tube, dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, N,N-dimethylpiperidin-4-amine were added to the solution with continuous N₂ purging and the followed by the addition of NaO^tBu. Finally compound 165 obtained from step (lxxii) was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 167 and 168 respectively. (lxxv) Compound 171 obtained in step (liv) was taken in dry DMF and K₂CO₃ was added to it. 1-bromobutane, Bromocyclopentane, 3-(bromomethyl)-5-fluoropyridine was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 172, 173 and 174 respectively. (lxxvi) Compound 177 obtained in step (liv) was taken in dry DMF and K₂CO₃ was added to it. 1-bromobutane, Bromocyclopentane was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 178 and 179 respectively. (lxxvii) Compound 183 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. Bromocyclopentane was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 184. (lxxviii) Compound 184 was treated with TFA in DCM at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 185. (lxxix) Compound 185 obtained in step (lxxviii) was taken in dry DMF and K₂CO₃ was added to it. 1-(bromomethyl)-4-methoxybenzene, 1-(bromomethyl)-4-fluorobenzene, 1- (bromomethyl)-3-fluorobenzene, 1-(bromomethyl)-2-fluorobenzene, 1- (bromomethyl)naphthalene, 5-(bromomethyl)-2-fluoropyridine, 3-(bromomethyl)-5- fluoropyridine, 1-(bromomethyl)-4-(trifluoromethyl)benzene was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 186, 187, 188, 189, 190, 191, 192 and 193 respectively. (lxxix) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Palladium acetate(0) and X-Phos were added to the toluene one by one and purged for 5-10 minutes. 1-bromo-4-fluorobenzene was added to the solution with continuous N2 purging and the followed by the addition of K3PO4. Finally compound 185 obtained from step (lxxviii) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 194. (lxxx) Compound 185 obtained in step (lxxviii) was taken in dry DCM and Et3N was added to it. 4-fluorobenzoyl chloride, acetyl chloride, isobutyryl chloride was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 195, 196 and 197 respectively. (lxxxi) Compound 200 was treated with 4(N) HCl in dioxane at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 201. (lxxxii) Compound 201 obtained in step (lxxxi) was taken in dry DMF and K₂CO₃ was added to it. Bromocyclopentane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 202. (lxxxiii) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Palladium acetate(0) and X-Phos were added to the toluene one by one and purged for 5-10 minutes. Morpholine, N-bocpiperazine, 1-methylpiperidin-4-amine, 1- methylpiperazine, 1-isopropylpiperazine, 2-methyl-2,5-diazabicyclo[2.2.1]heptane, pyrrolidine, piperidine was added to the solution with continuous N₂ purging and the followed by the addition of K3PO4 to attain different products. Finally compound 23 obtained from step (iii) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 203, 204, 207, 208, 209, 210, 211, 212. (lxxxiv) Compound 204 was treated with 4(N) HCl in dioxane at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 205. (lxxxv) Compound 205 obtained in step (lxxxiv) was taken in dry DMF and K₂CO₃ was added to it.2-bromoacetamide was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 206. (lxxxvi) In a pressure tube, dry dioxane was taken and sonicated with continuous N₂ purging for 15 minutes. Tetrakis(triphenylphosphine)palladium(0) and cyclohexylboronic acid or (1- (tert-butoxycarbonyl)piperidin-4-yl)boronic acid , were added to the dioxane one by one and purged for 5-10 minutes for different reaction. K₃PO₄ was added and purged for another 5 minutes. Finally compound 23 obtained from step (iii) was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 213, 214. (lxxxvii) Compound 214 obtained in step (lxxxvi) was taken in dry DMF and Et3N was added to it. Fmoc-Cl was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 215. (lxxxviii) Compound 215 was treated with 4(N) HCl in dioxane at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 216. (lxxxix) Compound 216 obtained in step (lxxxiv) was taken in dry DMF and K₂CO₃ was added to it.2-iodopropanewas added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 217. (lxxxx) In a pressure tube, dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Palladium acetate(0) and X-Phos were added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane, 1-methylpiperazine were added to the solution with continuous N2 purging and the followed by the addition of K3PO4 to attain different products. Finally 9-((6-bromopyridin-3-yl)methyl)-2-butoxy-7,9-dihydro-8H- purin-8-one was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 218 and 219. (lxxxxi) Compound 16 obtained in step (iii) was taken in dry DMF and Et3N was added to it. Fmoc-Cl was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 220. (lxxxxii) Compound 220 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 3 hours at room temperature to obtain the compound 221. (lxxxxiii) Compound 221 obtained in step (lxxxxii) was taken in dry DMF and Et3N was added to it. 1-bromo-3-chloro propane and 1-bromo-2-chloro ethane were added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 222 and 239. (lxxxxiv) Compound 222 obtained in step (lxxxxiii) was taken in dry DMF and K₂CO₃ was added to it. 2-oxa-5-azabicyclo[2.2.1]heptane, tert-butyl piperazine-1-carboxylate, 2,6- dimethylmorpholine, 3,5-dimethylmorpholine, 6-oxa-3-azabicyclo[3.1.1]heptane, 3-oxa-6- azabicyclo[3.1.1]heptane, morpholin-2-one, morpholin-3-one, 3-methylmorpholine, 2- methylmorpholine, morpholine-2-carbonitrile, 8-oxa-3-azabicyclo[3.2.1]octane, 6- methylmorpholin-2-one, 2,2-dimethylmorpholine, 2-methylmorpholine, 7-oxa-4- azaspiro[2.5]octan-6-one was added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237 and 238. (lxxxxv) Compound 239 obtained in step (lxxxxiii) was taken in dry DMF and K₂CO₃ was added to it. Morpholine was added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 240. (lxxxxvi) Compound 107 obtained in step () was taken in dry DMF and K₂CO₃ was added to it. 2-bromoethan-1-amine, 2-bromo-N-methylethan-1-amine, 2-bromo-N,N-dimethylethan-1- amine, 1-(2-bromoethyl)pyrrolidin-3-amine, 2-bromoacetamide, 2-bromo-N-methylacetamide, 2-bromo-N,N-dimethylacetamide were added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 241, 242, 243, 244, 245, 246, 247 respectively. (lxxxxvii) Lithium hydroxide was added portionwise to the THF and H₂O solution. Compound 14 obtained in step (i) was added to the solution to obtain the compound 248. (lxxxxviii) Compound 248 obtained in step (lxxxxvii), and diphenylphosphoryl azide was taken in dry DMA. Et₃N was added to the solution and refluxed for 12 hours to obtain the compound 249. (lxxxxix) Compound 249 obtained in step (lxxxxviii) was taken in dry DMF and K₂CO₃ was added to it. tert-butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 250. (lxxxxx) Compound 250 was treated with 4(N) HCl in dioxane at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 251. (lxxxxxi) Compound 251 was taken in dry DMF and K₂CO₃ was added to it. 2-bromo-N,N- dimethylacetamide was added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 252. (lxxxxxii) Compound 252 was taken in dry Dioxane and K₂CO₃ was added to it. Dimethylamine, 3-(1H-imidazol-1-yl)propan-1-amine, 2-(4-methylpiperazin-1-yl)ethan-1- amine, 3-(4-methylpiperazin-1-yl)propan-1-amine, (4-fluorophenyl)methanamine were added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 253, 254, 255, 256, 257 respectively. (lxxxxxiii) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Palladium acetate(0) and X-Phos were added to the toluene one by one and purged for 5-10 minutes.4-(trifluoromethyl)aniline was added to the solution with continuous N₂ purging and the followed by the addition of K₃PO₄ to attain different products. Finally compound 107 was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 258. (lxxxxxiv) Compound 258, 255 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 3 hours at room temperature to obtain the compound 259 and 261 respectively. (lxxxxxv) Compound 259 and 261 obtained in step (lxxxxxiv) was taken in dry DMF and K₂CO₃ was added to it. Methyl iodide and 2-iodopropane were added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 261 and 262 respectively. A screening method is provided using a HEK-Blue- hTLR7 or hTLR9 Secreted Alkaline Phosphatase (SEAP) reporter assay for the synthesized compounds of general Formula (I) with TLR7/9 agonism respectively. The method involves detecting TLR7/9 agonistic activity for the synthesized compounds of general Formula (I) by activation of respective TLR7/9-mediated NF- kB activation in a dose-dependent manner (figure 1 and figure 3). A screening method is provided using a HEK-Blue- hTLR7 or hTLR9 Secreted Alkaline Phosphatase (SEAP) reporter assay for the synthesized compounds of general Formula (I) with TLR7/9 antagonism respectively. The method involves detecting TLR7/9 antagonistic activity for the synthesized compounds of general Formula (I) by inhibiting respective TLR7/9-mediated NF- kB activation in a dose-dependent manner (figure 2 and figure 4). The primary reporter assay result provides a unique result in small molecule TLR modulators library. All these 8-oxopurine compounds with Structure 1 does not have -NH2 (primary amine) group at C-6 position and instead are replaced by hydrogen (H) at C-6. Compound 4 with N-9 position substituted with 3-carbon aliphatic chain containing morpholine group showed agonism property during the assay for TLR7 agonist where the same compound showed antagonism property during antagonism assay which is generally performed in presence of strong TLR agonist CL-264. Therefore, 8-oxopurine compound 4 with 3-carbon aliphatic chain containing morpholine group at N-9 position can be referred as small molecule TLR7 partial agonist but it has no effect on TLR9. This is significant as even out C-6 -NH2 group, compound 4 showed agonism. Compound 7, 8, 9, 10 was not active in both TLR7/9 agonism assay and TLR7/9 antagonism assay. Compound 13, 14, 17, 33 which differ with compound 4 at the N-9 position only by benzylic or substituted benzylic group emerged as selective TLR7 agonist. Compound 29, 35 which are having chained extension with ‘O’ from the N-9 positioned aromatic ring are completely inactive for both TLR7/9. In case of changing the “O” at C-2 position with “NH” the synthesized compounds lose its agonistic activity to a great extent. When the benzyl or substituted benzyl group at N-9 position is transformed into pyridyl or substituted pyridyl group in compound 42, it loses its activity as TLR7 agonist. In fact, it has no effect on TLR9 agonism. An interesting pattern comes into consideration when the N-7 position of purine ring is substituted with different aliphatic chains or ring. The N-7 substitution at compound 43, 44, 45, 47, 54, 70, 90, 104, 105, 107, 108, 112, 116, 118, 121, 122, 124, 125, 126, 127, 179, 187, 190, 192 leads the purine scaffold as specific TLR7 antagonist when the N-9 position is comprised of chain with anchored basic aliphatic ring or replaced with substituted benzylic groups. But the aromatic substitution at the N-7 position leads the compounds towards complete loss of TLR7 antagonistic activity. Hence the N-7 substitution can be denoted as very crucial point for the transformation of TLR7 agonist into a specific TLR7 antagonist. Another very fascinating result comes when the TLR9 agonism assay was performed for the same compounds. The compounds 107 and 112 which are mainly comprised of aliphatic chained amine or cyclic amine at N-7 position appeared as TLR9 agonist concurrently having TLR7 antagonism property. Probably the first-in-class crosslinked TLR9 agonist-TLR7 antagonist have been found which may have high significance during SLE disease prospect. Therefore, the N-7 position is found to be a turning point for the modulation of both TLR7/9 agonism-antagonism in 8-oxopurine scaffold. A strong SAR can be established around the N-7 position of 8-oxopurine ring to achieve the required TLR7/9 agonism-antagonism in apposite disease context. When the N- 9 position is changed with the incorporation of cyclic aliphatic amine directly keeping the N-7 as aliphatic substituted, a different result has been found in terms of antagonism. The compounds 188, 189, 191, 194 are showing very promising TLR9 antagonism at sub-micromolar concentration. But those compounds doesn’t possess any significant TLR7 antagonistic property.

EXAMPLES The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention. Temperatures are given in degree Celsius. The structures of final products, intermediates, and starting materials are confirmed by standard analytical methods, and spectroscopic characterization e.g., MS, NMR. Abbreviations used are those conventional in the art. All starting materials, reagents, catalysts, building blocks, acids, bases, dehydrating agents, and solvents utilized to synthesize the compounds of the present invention are either commercially available or can be produced by known organic synthesis methods in the art. Reactions that had sensitivity towards moisture or oxygen were carried out under a dry nitrogen or argon atmosphere. All the TLC was performed on silica gel plates (Merck silica gel 60, F254). The spots were visualized under UV light (λ=254 nm and 365 nm) or by taking the appropriate stain. Compounds were purified using Teledyne ISCO Combi flash R_f system using 230-400 mesh size silica gel. Microwave-assisted reactions were performed in CEM explorer^TM. ¹H NMR was recorded at 300 MHz (Bruker-DPX), 400 MHz (Jeol), and 600 MHz (Bruker- Avance) frequencies, and ¹³C NMR spectra were recorded at 75 MHz (Bruker-DPX), 100 MHz (Jeol), and 150 MHz (Bruker-Avance) frequency in CDCl₃ or CD₃OD or DMSO-d⁶ using TMS as the internal standard .The following abbreviations were used to explain multiplicities: s = singlet, d = doublet, t = triplet, q = quartet, p = pentate, m = multiplet, br. = broad. Coupling constants, J reported in Hertz unit (Hz). High-resolution mass spectra, HRMS (m/z), were measured using EI (Jeol-JMS 700 mass spectrometer), ESI (Q-Tof Micro mass spectrometer) techniques, and ESI (LTQ Orbitrap XL mass spectrometer). The purity of all the compounds was determined to be >95%, analyzed by Agilent Infinity Prep. HPLC system using Bio Suite Phenyl C18 Column (7.5 mm × 75 mm, 10 µm, SKU: 186002159, from waters) Hitachi HPLC using column Xtimate C18 (4.6 mm × 150 mm, 5.0 μm) using a gradient elution of acetonitrile in water 0−90% for 8 to 20 min and flow rate 1 mL/min with detection at 220 nm, 210 nm and 254 nm wavelength. Example 1 General Procedure A: Nucleophilic aromatic substitution by primary (aliphatic/benzylic) amines: Requisite amine (1 equivalent) was added to a stirred solution of starting material (1 equivalent) and Et3N (1 equivalent) in10 ml dry acetonitrile at ice-cold condition. The reaction mixture was stirred at room temperature for 3-4 hours. Consumption of starting material was confirmed by TLC. Water was added to quench the reaction. The aqueous solution was extracted with ethyl acetate and the organic layer was dried over Na2SO4 and evaporated under vacuum. Flash column chromatography was performed if needed to achieve the pure product. Example 2 General Procedure B: One-pot nucleophilic aromatic substitution and ester hydrolysis by alkoxy groups: Sodium tert-butoxide (2 eqivalent) was added portion wise to the 10 ml of required protic solvent (EtOH, n-propanol, n-BuOH). The solution was stirred at room temperature for 30 mins. C-4 substituted pyrimidine compound prepared by general procedure A (1 equivalent) was then added slowly to the solution at ice cold condition. The reaction mixture was stirred for 8 hours at room temperature. After completion of the reaction, the solvent was evaporated under reduced pressure. The residue was neutralized by the dropwise addition of 4 (N) HCl and purified by reverse phase flash column chromatography to obtain the desired compound. Example 3 General Procedure C: Ester hydrolysis: A solution of KOH (4 equivalent) in water (2.5 ml) was added to a stirred solution of required ester (1 equivalent) in THF (7.5 ml). The reaction mixture was stirred at 140 °C for 8 hours. After the consumption of staring ester, organic layers were removed under reduced pressure and the water part was neutralized by the dropwise addition of 4 (N) HCl. The precipitate was filtered, washed with water (500 ml) for 2 times and dried under vacuum to afford the pure compound. Example 4 General Procedure D: Curtius rearrangement followed by cyclization: Suitably substituted compound prepared by either general procedure B or C (1 equivalent) and diphenylphosphoryl azide (1.8 equivalent) were taken in 5 mL of dry DMA. Et₃N (1.2 equivalent) was added to it. After stirring the reaction mixture at room temperature for 1 hour, it was refluxed for 12 hours at 140 °C. Completion of the reaction was monitored by TLC. Boiling water was poured into the reaction mixture to quench. The aqueous solution was extracted with ethyl acetate and the organic layer was dried over Na₂SO₄ and evaporated under vacuum. The residue was subjected to flash column chromatography for purification. Example 5 General Procedure E: Nucleophilic aromatic substitution by aliphatic/benzylic bromides: Apposite bromide (1 equivalent) was added to a stirred solution of purine analogs, prepared by general procedure D (1 equivalent) and K₂CO₃ (1-1.5 equivalent) or Et3N (1-1.5 equivalent) in 3 ml dry DMF. The reaction mixture was stirred at room temperature for 2-3 hours. The completion of the reaction was confirmed by TLC. Upon completion, the reaction mixture was partitioned between EtOAc (50ml) and ice-water (50 ml). The organic layer was isolated and washed with saturated brine (50 mL) for 2 times. The resulting crude mixture was purified by flash column chromatography. Example 6 Synthesis of ethyl 2-chloro-4-((3-morpholinopropyl)amino)pyrimidine-5-carboxylate (2) :The desired compound 2was synthesized by general procedure A using ethyl 2,4- dichloropyrimidine-5-carboxylate 1 (1g, 4.52 mmol),3-morpholinopropan-1-amine (0.67 ml, 4.52 mmol) and Et3N (0.63 ml 4.52 mmol) in 10 ml dry acetonitrile. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography (Silica gel, mesh size 100-200) eluting with 20% ethyl acetate in hexane to provide compound 2(85%)as white crystalline solid. Example 7 Synthesis of2-butoxy-4-((3-morpholinopropyl)amino)pyrimidine-5-carboxylic acid (3) : The required compound 3 was synthesized by general procedure B using Compound 2 (0.500 g, mmol), Sodium t-butoxide (0.292 g, mmol) and 10 mL of n-BuOH. The residue was purified by reverse phase column chromatography eluting with 30% acetonitrile-water to obtain pure compound 3(80%) as white powder.¹H NMR (400 MHz, DMSO-d6) δ in ppm 10.05(s, 1H), 8.35(s, 1H), 4.17(t, J= 6.8 Hz, 2H), 3.55(t, J= 4.8 Hz, 4H), 3.36(q, J= 6.8 Hz, 2H) 2.37-2.26(m, 6H), 1.70-1.59(m, 4H), 1.42-1.32 (m, 2H), 0.90(t, J= 7.6 Hz, 3H). Example 8 Synthesis of 2-butoxy-9-(3-morpholinopropyl)-7H-purin-8(9H)-one(4): The desired compound 3 was synthesized by general procedure D using Compound 3 (0.500g, 1.48 mmol), Diphenylphosphoryl azide (0.57 ml, 2.65 mmol), Et₃N (0.24 mL, 1.77mmol) in dry 5 mL of DMA. Completion of the reaction was monitored by TLC. Boiling water was poured into the reaction mixture. The aqueous solution was extracted with ethyl acetate and the organic layer was dried over Na2SO4 and evaporated under vacuum. The residue was purified by silica gel column chromatography eluting with 2% methanol in chloroform, to provide compound 4 (78%) as white solid.¹H NMR (400 MHz, CDCl3) δ in ppm 7.95(s, 1H), 4.30 (t, J= 6.8 Hz, 2H), 3.98 (t, J= 6.8 Hz, 2H), 3.62(t, J= 4.8 Hz, 4H), 2.47(t, J= 7.2 Hz, 2H), 2.44- 2.39(m, 4H), 2.02-1.99(m, 2H), 1.78(qu, J= 7.2 Hz, 2H),1.52-1.43(m, 2H), 0.95(t, J= 7.6 Hz, 3H). Example 9 Synthesis of ethyl 2-chloro-4-((3-(piperidin-1-yl)propyl)amino)pyrimidine-5-carboxylate (5) : Compound 1 (1g, 4.52 mmol), Et₃N (0.63 mL, 4.52 mmol), and 3-(piperidin-1-yl)propan- 1-amine (0.71 mL, 4.52 mmol) were dissolved in 5 mL of dry acetonitrile . The reaction was then performed according to general procedure A. The residue was purified by silica gel column chromatography eluting with 2% methanol in chloroform to provide compound 5 (85%) to obtain pure compound 5 as brown solid. Example 10 Synthesis of 2-butoxy-4-((3-(piperidin-1-yl)propyl)amino)pyrimidine-5-carboxylic acid (6) : Compound 5(0.500 g, 1.52 mmol) was added in the pre-stirred solution of sodium t- butoxide (0.294 mg, 1.52 336.4360mmol) in 10 ml of n-BuOH. The reaction was then performed according to general procedure B. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 6 (80%) to as brown solid. Example 11 Synthesis of 2-butoxy-9-(3-(piperidin-1-yl)propyl)-7H-purin-8(9H)-one (7) : Compound 6 (0.500 g, 1.48 mmol) and Diphenylphosphoryl azide (0.575 mL, 2.67 mmol) were taken in dry 5 mL of DMA and Et₃N (0.24 mL, 1.78 mmol) was added to it. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography eluting with 60% CMA (85% chloroform + 10% methanol + 5% ammonia) in chloroform to obtain pure compound 7(78%) as off-white solid. Example 12 Synthesis of ethyl 2-chloro-4-((3-(4-ethylpiperazin-1-yl)propyl)amino)pyrimidine-5- carboxylate (8) : Compound 1 (1g, 4.52 mmol), Et3N (0.63 mL, 4.52 mmol), and 3-(4-ethylpiperazin-1- yl)propan-1-amine (0.76 mL, 4.52 mmol) were dissolved in 5 mL of dry acetonitrile . The reaction was then performed according to general procedure A and the residue was purified by flash column chromatography eluting with 5 % methanol in chloroform to obtain pure compound 8(80%) as brown semisolid. Example 13 Synthesis of 2-butoxy-4-((3-(4-ethylpiperazin-1-yl)propyl)amino)pyrimidine-5- carboxylic acid (9) : Compound 8 (0.500 g, 1.41 mmol) was added in the pre-stirred solution of sodium t-butoxide (0.270 g, 2.81 mmol) in 10 ml of n-BuOH. The reaction was then performed according to general procedure B.The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 9 (77%) as brown solid. Example 14 Synthesis of 2-butoxy-9-(3-(4-ethylpiperazin-1-yl)propyl)-7H-purin-8(9H)-one(10): Compound 9 (0.500 g, 1.37 mmol) and Diphenylphosphoryl azide (0.53 mL, 2.46 mmol) were taken in dry 5 mL of DMA and Et₃N (0.23 mL, 1.64 mmol) was added to it. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography eluting with 80% CMA (85% chloroform + 10% methanol + 5% ammonia) in chloroform to obtain pure compound 11 (78%) as brown solid. Example 15 Synthesis of ethyl 4-(benzylamino)-2-chloropyrimidine-5-carboxylate (11): Compound 1 (1g, 4.52 mmol), Et₃N (0.63 mL, 4.52mmol), and phenylmethanamine (0.49 mL, 4.52 mmol) were dissolved in 5 mL of dry acetonitrile. The reaction was then performed according to general procedure A. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 7 % ethyl acetate in hexane to provide compound 11 (88%) as white crystalline solid to obtain pure compound 8 as white fluffy solid. Example 16 Synthesis of 4-(benzylamino)-2-butoxypyrimidine-5-carboxylic acid (12): Compound 11 (0.500 g, 1.72 mmol) was added in the pre-stirred solution of sodium t-butoxide (0.329 g, 3.43 mmol) in 10 ml of n-BuOH. The reaction was then performed according to general procedure B.The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 12 (83%) as white solid. Example 17 Synthesis of 9-benzyl-2-butoxy-7H-purin-8(9H)-one(13): Compound 12 (0.500g, 1.66 mmol) and Diphenylphosphoryl azide (0.64 mL, 2.99 mmol) were taken in dry 5 mL of DMA and Et₃N (0.28 mL, 1.99 mmol) was added to it. The reaction was then performed according to general procedure Dand the residue was purified by flash column chromatography eluting with 2% methanol in chloroform, to provide compound 13 (84%) as brown solid. Example 18 Synthesis of ethyl 2-chloro-4-((4-methoxybenzyl)amino)pyrimidine-5-carboxylate(14): Compound 1 (1g, 4.52 mmol), Et3N (0.63 mL, 4.52 mmol), and (4- methoxyphenyl)methanamine (0.59 mL, 4.52 mmol) were dissolved in 5 mL of dry acetonitrile. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 7 % ethyl acetate in hexane to provide compound 14 (89%) as white fluffy solid.¹H NMR (400 MHz, Chloroform-d) δ 8.65 (s, 1H), 8.59 (t, J=5.6, 1H), 7.25 (d, J = 8.8 Hz, 2H), 6.85 (d, J = 8.8 Hz, 2H), 4.63 (d, J = 5.6 Hz, 2H), 4.30 (q, J = 7.2 Hz, 2H), 3.77 (s, 3H), 1.34 (t, J = 7.2 Hz, 3H). Example 19 Synthesis of 2-butoxy-4-((4-methoxybenzyl)amino)pyrimidine-5-carboxylic acid (15): Compound 14 (0.500 g, 1.55 mmol) was added in the pre-stirred solution of sodium t-butoxide (0.298 g, 3.11 mmol) in 10 ml of n-BuOH. The reaction was then performed according to general procedure B. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 15 (85%) as white solid.¹H NMR (400 MHz, DMSO-d6) δ 10.49 (s, 1H), 8.34 (s, 1H), 7.19 (d, J= 8.4 Hz, 2H), 6.84 (d, J= 8.8 Hz, 2H), 4.44 (d, J = 5.6 Hz, 2H), 4.14 (t, J = 6.8 Hz, 2H), 3.68 (s, 3H), 1.62-1.55 (m, 2H), 1.37-1.28 (m, 2H), 0.86 (t, J = 7.6 Hz, 3H). Example 20 Synthesis of 2-butoxy-9-(4-methoxybenzyl)-7H-purin-8(9H)-one(16): Compound 15 (0.500 g, 1.51 mmol) and Diphenylphosphoryl azide (0.58 mL, 2.72 mmol) were taken in dry 5 mL of DMA and Et₃N (0.25 mL, 1.81 mmol) was added to it. The reaction was then performed according to general procedure D. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography eluting with 2% methanol in chloroform, to provide compound 16 (85%) as white solid.¹H NMR (400 MHz, Chloroform-d) δ 7.98 (s, 1H), 7.43 (d, J = 8.4 Hz, 2H), 6.82 (d, J = 8.8 Hz, 2H), 5.01 (s, 2H), 4.33 (t, J = 6.8 Hz, 2H), 3.75 (s, 3H), 1.83-1.76 (m, 6.8 Hz, 2H), 1.54-1.44 (m, 2H), 0.97 (t, J = 7.6 Hz, 3H). Example 21 Synthesis of 2-butoxy-9-(4-hydroxybenzyl)-7H-purin-8(9H)-one(17): Compound 16 (0.200 g, 0.61 mmol) and 5 ml DCM were taken in a pressure tube. A solution of BBr₃(0.086 mL, .914 mmol) was added dropwise to the reaction mixture in ice-cold condition. The reaction mixture was stirred at 0 °C for 30 mins. Upon completion of the reaction, cold water was added into the mixture to quench the reaction. The aqueous solution was extracted with chloroform and the organic layer was dried over Na₂SO₄ and evaporated under vacuum. The residue was purified by silica gel column chromatography eluting with 2% methanol in chloroform, to provide compound 17 as white solid. ¹H NMR (400 MHz, Methanol-d₄) δ 7.90 (s, 1H), 7.26 (d, J = 7.2 Hz, 2H), 6.70 (d, J = 6.8 Hz, 2H), 4.91 (s, 2H), 4.37-4.30 (m, 2H), 1.78-1.69 (m, 2H), 1.52-1.43 (m, 2H), 0.97 (t, J = 6.8 Hz, 3H). Example 22 Synthesis of ethyl 2-chloro-4-((4-aminobenzyl)amino)pyrimidine-5-carboxylate(18) : Compound 1 (1g, 4.52 mmol), Et₃N (0.63 mL, 4.52 mmol), and 4-(aminomethyl)aniline (0.59 mL, 4.52 mmol) were dissolved in 5 mL of dry acetonitrile . The reaction was then performed according to general procedure A to obtain pure compound 18. Example 23 Synthesis of 2-butoxy-4-((4-aminobenzyl)amino)pyrimidine-5-carboxylic acid (19) : Compound 18 (0.500 g, 1.63 mmol) was added in the pre-stirred solution of sodium t-butoxide (0.314 g, 3.27 mmol) in 10 ml of n-BuOH. The reaction was then performed according to general procedure B to obtain pure compound 19. Example 24 Synthesis of 2-butoxy-9-(4-aminobenzyl)amino)-7H-purin-8(9H)-one(20) : Compound 19 (0.500g, 1.58 mmol) and Diphenylphosphoryl azide (0.61 mL, 2.85 mmol) were taken in dry 5 mL of DMA and Et₃N (0.27 mL, 1.90 mmol) was added to it. The reaction was then performed according to general procedure D to obtain pure compound 20. Example 25 Synthesis of ethyl 2-chloro-4-((4-bromobenzyl)amino)pyrimidine-5-carboxylate (21) : Compound 1 (1g, 4.52 mmol), Et3N (0.63 mL, 4.52 mmol), and (4-bromophenyl)methanamine ( 0.51 mL, 4.52 mmol) were dissolved in 5 mL of dry acetonitrile . The reaction was then performed according to general procedure A to obtain pure compound21. Example 26 Synthesis of 2-butoxy-4-((4-bromobenzyl)amino)pyrimidine-5-carboxylic acid (22) : Compound 21 (0.500 g, 1.61 mmol) was added in the pre-stirred solution of sodium t-butoxide (0.310 g, 3.23 mmol) in 10 ml of n-BuOH. The reaction was then performed according to general procedure B to obtain pure compound 22. Example 27 Synthesis of 2-butoxy-9-(4-bromobenzyl)amino)-7H-purin-8(9H)-one(23): Compound 22 (0.500g, 1.57 mmol) and Diphenylphosphoryl azide (g, mmol) were taken in dry 5 mL of DMA and Et3N (0.26 mL, 1.88 mmol) was added to it. The reaction was then performed according to general procedure D to obtain pure compound 23. Example 28 Synthesis of ethyl 2-chloro-4-((4-(dimethylamino)benzyl)amino)pyrimidine-5- carboxylate (24): Compound 1 (1g, 4.52 mmol), Et3N (0.63 mL, 4.52 mmol), and 4- (aminomethyl)-N,N-dimethylaniline ( 0.64 mL, 4.52 mmol) were dissolved in 5 mL of dry acetonitrile . The reaction was then performed according to general procedure A to obtain pure compound24. Example 29 Synthesis of 2-butoxy-4-((4-(dimethylamino)benzyl)amino)pyrimidine-5-carboxylic acid (25) : Compound 24 (0.500 g, 1.39 mmol) was added in the pre-stirred solution of sodium t- butoxide (0.267 g, 2.78 mmol) in 10 ml of n-BuOH. The reaction was then performed according to general procedure B to obtain pure compound 25. Example 30 Synthesis of 2-butoxy-9-(4-(dimethylamino)benzyl)amino)-7H-purin-8(9H)-one(26): Compound 25 (0.500 g, 1.35 mmol) and Diphenylphosphoryl azide (0.52 mL, 2.43 mmol) were taken in dry 5 mL of DMA and Et3N (0.22 mL, 1.62 mmol) was added to it. The reaction was then performed according to general procedure D to obtain pure compound 26. Example 31 Synthesis of tert-butyl 2-butoxy-9-(4-hydroxybenzyl)-8-oxo-8,9-dihydro-7H-purine-7- carboxylate(27): Compound 17(0.500 g, 1.59 mmol) was dissolved in 5 ml dry THF and boc-anhydride (0.43 ml, 1.91 mmol) was added dropwise at ice cold condition. The reaction mixture was stirred at 0 °C for 30 mins. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 10 % ethyl acetate in hexane to provide compound 27 (72%) as white fluffy solid. ¹H NMR (400 MHz, Chloroform-d) δ 8.46 (s, 1H), 7.35 (d, J = 8.4 Hz, 2H), 6.74 (d, J = 8.8 Hz, 2H), 4.96 (s, 2H), 4.37 (t, J = 6.8 Hz, 2H), 1.83-1.76 (m, 2H), 1.63 (s, 9H), 1.54-1.44 (m, 2H), 0.96 (t, J = 7.8 Hz, 3H). Example 32 Synthesis of tert-butyl 2-butoxy-9-(4-(2-(1,3-dioxoisoindolin-2-yl)ethoxy)benzyl)-8-oxo- 8,9-dihydro-7H-purine-7-carboxylate (28): Compound 27 (0.100g, 0.24 mmol), Et3N (0.02 mL, 0.14 mmol), and N-(2- Bromoethyl)phthalimide (0.92 g, 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 5 % ethyl acetate in hexane to provide compound 28 (92%) as white solid. ¹H NMR (400 MHz, Chloroform-d) δ 7.89 (s, 1H), 7.75-7.72 (m, 2H), 7.70 – 7.67 (m, 2H), 7.41 (d, J = 8.4 Hz, 2H), 7.06 (d, J = 8.8 Hz, 2H), 4.97 (s, 2H), 4.28 (t, J = 6.8 Hz, 2H), 4.14 – 4.11 (m, 2H), 4.03-4.00 (m, 2H), 1.79-1.72 (m, 2H), 1.54 (s, 1H), 1.49-1.44 (m, 2H), 0.95 (t, J = 7.6 Hz, 3H). Example 33 Synthesis of 9-(4-(2-aminoethoxy)benzyl)-2-butoxy-7,9-dihydro-8H-purin-8-one(29): Compound 28 (0.50g, 0.085 mmol) was dissolved in 5 ml of EtOH and NH₂-NH₂. H₂O (0.01 mL, 0.34 mmol) was added to it. The reaction mixture was refluxed for 2 hours. After completion of the reaction, a white-coloured precipitate has been formed upon cooling. The precipitate was filtered and the filtrate was evaporated to vacuum. The residue was subjected to flash column chromatography, eluting with 60% CMA (85% chloroform + 10% methanol + 5% ammonia) in chloroform to obtain pure compound 29(75%) as gummy transparent liquid.¹H NMR (400 MHz, Chloroform-d) δ 7.89 (s, 1H), 7.30 (d, J = 8.4 Hz, 2H), 6.70 (d, J = 8.8 Hz, 2H), 4.92 (s, 2H), 4.30 (t, J = 6.4 Hz, 2H), 3.84 (t, J = 6.4 Hz, 2H), 2.97 (t, J = 6.4 Hz, 3H), 1.78-1.71 (m, 2H), 1.50-1.40 (m, 2H), 0.93 (t, J = 7.6 Hz, 3H). Example 34 Synthesis of ethyl 4-((4-(((tert-butoxycarbonyl)amino)methyl)benzyl)amino)-2- chloropyrimidine-5-carboxylate(30): Compound 1 (1g, 4.52 mmol), Et3N (0.63 mL, 4.52mmol), and 4-(Boc-amino)benzylamine (0.91 mL, 4.52 mmol) were dissolved in 5 mL of dry acetonitrile . The reaction was then performed according to general procedure A. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 15 % ethyl acetate in hexane to provide compound 30(88%) as white crystalline solid to obtain pure compound 8 as white fluffy solid. Example 35 Synthesis of 2-butoxy-4-((4-(((tert- butoxycarbonyl)amino)methyl)benzyl)amino)pyrimidine-5-carboxylic acid (31) Compound 30 (0.500 g, 1.18 mmol) was added in the pre-stirred solution of sodium t-butoxide (0.228 g, 2.37 mmol) in 10 ml of n-BuOH. The reaction was then performed according to general procedure B. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 31 (78%) as white solid. Example 36 Synthesis of tert-butyl (4-((2-butoxy-8-oxo-7,8-dihydro-9H-purin-9- yl)methyl)benzyl)carbamate (32) Compound 31 (0.500 g, 1.16 mmol) and Diphenylphosphoryl azide (0.44 mL, 2.09 mmol) were taken in dry 5 mL of DMA and Et₃N (0.19 mL, 1.39 mmol) was added to it. The reaction was then performed according to general procedure D. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography, eluting with 5% methanol in chloroform, to provide compound 32 (80%) as white solid. Example 37 Synthesis of 9-(4-(aminomethyl)benzyl)-2-butoxy-7,9-dihydro-8H-purin-8-one (33): Compound 32 (0.05 g, 0.11 mmol) was taken in dioxane and 2 ml of 4(N) HCl in dioxane was added to the solution. The reaction mixture was stirred for 2 hours at room temperature. Upon completion of the reaction the organic solvent was evaporated in vacuum and sprinkle of water was added to it. The solution was then neutralized with 4(N) NaOH. The water part was extracted with chloroform and evaporated in reduced pressure. The residue was subjected to flash column chromatography, eluting with 30% CMA (85% chloroform + 10% methanol + 5% ammonia) in chloroform to obtain pure compound 33 (85%) as light-brown solid. Example 38 Synthesis of tert-butyl 2-butoxy-9-(4-(2-chloroethoxy)benzyl)-8-oxo-8,9-dihydro-7H- purine-7-carboxylate (34): Compound 27 (0.100g, 0.24 mmol), Et3N (0.05 mL, 0.36 mmol), and 1-Bromo-2-chloro ethane (0.016 mL, 0.36mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 8 % ethyl acetate in hexane to provide compound 34 (88%) as white solid.¹H NMR (400 MHz, Chloroform-d) δ 7.97 (s, 1H), 7.50 (d, J = 8.8 Hz, 2H), 7.09 (d, J = 8.6 Hz, 2H), 5.04 (s, 2H), 4.32 (t, J = 6.8 Hz, 2H), 4.13 (t, J= 6.0 Hz, 2H), 3.78 (t, J = 6.0 Hz, 2H), 1.81-1.74 (m,2H), 1.51 (s, 9H), 1.49- 1.43 (m, 2H), 0.95 (t, J = 7.6 Hz, 3H). Example 39 Synthesis of 2-butoxy-9-(4-(2-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)ethoxy)benzyl)-7,9-dihydro-8H-purin-8-one (35): Compound 34 (0.05 g, 0.21 mmol), K₂CO₃ (0.034g, 0.13 mmol), and 2-Methyl-2,5- diazabicyclo[2.2.1]heptane dihydrobromide (0.043 g, 0.157 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 40% CMA (85% chloroform + 10% methanol + 5% ammonia) in chloroform, to provide compound 35 (90%) as gummy liquid.¹H NMR (600 MHz, Chloroform-d) δ 7.90 (s, 1H), 7.36 (d, J = 8.4 Hz, 2H), 6.74 (d, J = 8.4 Hz, 2H), 4.99 (s, 2H), 4.36 (t, J = 6.6 Hz, 2H), 3.88 (t, J = 6.0 Hz, 2H), 3.34 (s, 1H), 3.24 (s, 1H), 2.91 – 2.86 (m, 2H), 2.78-2.74 (m, 1H), 2.69 (d, J = 9.0 Hz, 1H), 2.65 (dd, J = 10.2, 2.4 Hz, 1H), 2.59 (d, J = 9.6 Hz, 1H), 2.36 (s, 3H), 1.85 – 1.80 (m, 2H), 1.78 (d, J = 10.2 Hz, 1H), 1.65 (d, J = 10.2 Hz, 1H), 1.55-1.49 (m, 2H), 1.00 (t, J = 7.2 Hz, 3H). Example 40 Synthesis of 2-butoxy-9-(4-(2-(pyrrolidin-1-yl)ethoxy)benzyl)-7,9-dihydro-8H-purin-8- one (36): Compound 34 (0.05 g, 0.11 mmol), K₂CO₃ (0.017 g, 0.13 mmol), and pyrrolidine (0.013 mL, 0.157 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. The reaction was then performed according to the synthetic procedure of compound 35 to obtain pure compound 36. Example 41 Synthesis of 2-butoxy-9-(4-(2-(dimethylamino)ethoxy)benzyl)-7,9-dihydro-8H-purin-8- one (37): Compound 34 (0.05 g, 0.11 mmol), K₂CO₃ (0.017 g, 0.13 mmol), and dimethylamine (0.011 mL, 0.157 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. The reaction was then performed according to the synthetic procedure of compound 35 to obtain pure compound 37. Example 42 Synthesis of 2-butoxy-9-(4-(2-(piperazin-1-yl)ethoxy)benzyl)-7,9-dihydro-8H-purin-8- one (38): Compound 34 (0.05 g, 0.11 mmol), K₂CO₃ (0.017 g, 0.13 mmol), and tert-butyl piperazine-1- carboxylate (0.03 mL, 0.157 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was then performed according to the synthetic procedure of compound 35 to obtain pure compound 38. Example 43 Synthesis of 2-butoxy-9-(4-(2-(piperazin-1-yl)ethoxy)benzyl)-7,9-dihydro-8H-purin-8- one (39): Compound 34 (0.05 g, 0.11 mmol), K₂CO₃ (0.017 g, 0.13 mmol), and morpholine (0.013 mL, 0.157 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was then performed according to the synthetic procedure of compound 35 to obtain pure compound 39. Example 44 Synthesis of ethyl 2-chloro-4-(((6-methoxypyridin-3-yl)methyl)amino)pyrimidine-5- carboxylate (40): Compound 1 (1g, 4.52 mmol), Et3N (0.63 mL, 4.52 mmol), and (6- Methoxypyridin-3-yl)methanamine (0.56 mL, 4.52 mmol) were dissolved in 5 mL of dry acetonitrile. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 7 % ethyl acetate in hexane to provide compound 40 (86%) as white fluffy solid. Example 45 Synthesis of 2-butoxy-4-(((6-methoxypyridin-3-yl)methyl)amino)pyrimidine-5- carboxylic acid (41): Compound 40 (0.500 g, 1.55 mmol) was added in the pre-stirred solution of sodium t-butoxide (0.298 g, 3.11 mmol) in 10 ml of n-BuOH. The reaction was then performed according to general procedure B. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 41 (81%) as white solid. Example 46 Synthesis of 2-butoxy-9-((6-methoxypyridin-3-yl)methyl)-7,9-dihydro-8H-purin-8-one (42): Compound 41 (0.500 g, 1.51 mmol) and Diphenylphosphoryl azide (0.58 mL, 2.72 mmol) were taken in dry 5 mL of DMA and Et₃N (0.25 mL, 1.81 mmol) was added to it. The reaction was then performed according to general procedure D. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography eluting with 2% methanol in chloroform, to provide compound 42(87%) as white solid. Example 47 Synthesis of 2-butoxy-7-butyl-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one (43): Compound 4 (0.05 g, 0.15 mmol), K₂CO₃ (0.03 g, 0.22 mmol), and 1-bromobutane (0.019 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 43 (95%) as white solid.¹H NMR (600 MHz, Chloroform-d) δ 7.80 (s, 1H), 4.25-4.20 (m, 2H), 3.93-3.89 (m, 2H), 3.78-3.74 (m, 2H), 3.56-3.50 (brs, 4H), 2.36-2.25 (m, 6H), 1.91-1.84 (m, 2H), 1.73-1.68 (m, 2H), 1.66-1.62 (m, 2H), 1.44-1.37 (m, 2H), 1.32- 1.25 (m, 2H), 0.90-0.84 (m, 6H). Example 48 Synthesis of 2-butoxy-7-(2-hydroxyethyl)-9-(3-morpholinopropyl)-7,9-dihydro-8H- purin-8-one (44): Compound 4 (0.05 g, 0.15 mmol), K₂CO₃ (0.03 g, 0.22 mmol), and 2-bromoethanol (0.013mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 43 (91%) as white solid.¹H NMR (400 MHz, Chloroform-d) δ 7.98 (s, 1H), 4.29 (t, J = 6.8 Hz, 2H), 4.00 – 3.92 (m, 6H), 3.59 (t, J = 6.8 Hz, 4H), 2.40 (t, J = 7.2 Hz, 2H), 2.36 (t, J = 4.4 Hz, 4H), 1.97-1.90 (m, 2H), 1.80-1.73 (m, 2H), 1.51-1.42 (m, 2H), 0.95 (t, J = 7.2 Hz, 3H). Example 49 Synthesis of 2-butoxy-7-(3-hydroxypropyl)-9-(3-morpholinopropyl)-7,9-dihydro-8H- purin-8-one(45): Compound 4 (0.05 g, 0.15 mmol), K₂CO₃ (0.03 g, 0.22 mmol), and 3-bromopropanol (0.016 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 45(91%) as white solid. ¹H NMR (400 MHz, Chloroform-d) δ 7.94 (s, 1H), 4.31 (t, J = 6.8 Hz, 2H), 4.01 (m, 4H), 3.64-3.58 (m, 6H), 2.43 – 2.35 (m, 6H), 1.99-1.94 (m, 4H), 1.82-1.75 (m, 2H), 1.53-1.43 (m, 2H), 0.96 (t, J = 7.6 Hz, 3H). Example 50 Synthesis of 2-(3-(2-butoxy-9-(3-morpholinopropyl)-8-oxo-8,9-dihydro-7H-purin-7- yl)propyl)isoindoline-1,3-dione (46): Compound 4 (0.05 g, 0.15 mmol), K₂CO₃ (0.03 g, 0.22 mmol), and N-(3- Bromopropyl)phthalimide (0.05 g, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 46(95%) as white solid. ¹H NMR (400 MHz, Chloroform-d) δ 7.87 (s, 1H), 7.83 (dd, J = 5.6, 3.0 Hz, 2H), 7.72 (dd, J = 5.5, 3.0 Hz, 2H), 4.29 (t, J = 6.8 Hz, 2H), 3.96 (t, J = 6.8 Hz, 2H), 3.92 (t, J = 7.2 Hz, 2H), 3.77 (t, J = 7.2 Hz, 2H), 3.61 (t, J = 4.8 Hz, 4H), 2.43 – 2.35 (m, 6H), 2.21-2.14 (m, 2H), 1.99-192 (m, 2H), 1.81-1.74 (m, 2H), 1.53-1.44 (m, 2H), 0.96 (t, J = 7.6 Hz, 3H). Example 51 Synthesis of 2-(3-(2-butoxy-9-(3-morpholinopropyl)-8-oxo-8,9-dihydro-7H-purin-7- yl)propyl)isoindoline-1,3-dione (47): Compound 46(0.50g, 0.09 mmol) was dissolved in 5 ml of EtOH and NH2-NH2. H2O (0.01 mL, 0.34 mmol) was added to it. The reaction mixture was refluxed for 2 hours. After completion of the reaction, a white-coloured precipitate has been formed upon cooling. The precipitate was filtered and the filtrate was evaporated to vacuum. The residue was subjected to flash column chromatography, eluting with 60% CMA (85% chloroform + 10% methanol + 5% ammonia) in chloroform to obtain pure compound 47 (86%) as gummy transparent liquid. 1H NMR (400 MHz, Chloroform-d) δ 7.92 (s, 1H), 4.30 (t, J = 6.8 Hz, 2H), 4.00-3.93 (m, 4H), 3.61 (t, J = 6.0 Hz, 4H), 2.71 (t, J = 6.8 Hz, 2H), 2.43 – 2.35 (m, 6H), 1.98-1.91 (m, 2H), 1.89- 1.82 (m, 2H), 1.82 – 1.76 (m, 4H), 1.53-1.43 (m, 2H), 0.96 (t, J = 7.6 Hz, 3H). Example 52 Synthesis of 7-allyl-2-butoxy-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one (48): Compound 4 (0.05 g, 0.15 mmol), K₂CO₃ (0.03 g, 0.22 mmol), and allyl bromide (0.015 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 48(92%) as white solid. ¹H NMR (400 MHz, Chloroform-d) δ 7.83 (s, 1H), 5.86 (ddt, J = 16.9, 10.2, 5.6 Hz, 1H), 5.29 (dq, J = 5.6, 1.2 Hz, 1H), 5.26 (dq, J = 12.8, 1.2 Hz, 1H), 4.45 (dt, J = 5.6, 2.0 Hz, 2H), 4.29 (t, J = 6.4 Hz, 2H), 3.98 (t, J = 6.8 Hz, 2H), 3.59 (t, J = 4.8 Hz, 2H), 2.42 – 2.35 (m, 6H), 1.95 (m, 2H), 1.80-1.73 (m, 2H), 1.51-1.42 (m, 2H), 0.94 (t, J = 7.6 Hz, 3H). Example 53 Synthesis of 7-benzyl-2-butoxy-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one (49): Compound 13 (0.05 g, 0.15 mmol), K₂CO₃ (0.03 g, 0.22 mmol), and benzyl bromide (0.021 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 49 (94%) as white solid.¹H NMR (400 MHz, Chloroform-d) δ 7.63 (s, 1H), 7.35 – 7.27 (m, 5H), 4.99 (s, 2H), 4.25 (t, J = 6.8 Hz, 2H), 4.02 (t, J = 6.8 Hz, 2H), 3.61 (t, J = 4.8 Hz, 4H), 2.46-2.37 (m, 6H), 2.03-1.96 (m, 2H), 1.78 – 1.71 (m, 2H), 1.49- 1.42 (m, 2H), 0.93 (t, J = 7.6 Hz, 3H). Example 54 Synthesis of 9-benzyl-2-butoxy-7-butyl-7,9-dihydro-8H-purin-8-one (50): Compound 13 (0.05 g, 0.17 mmol), K₂CO₃ (0.034 g, 0.25 mmol), and 1-bromobutane (0.021 mL, 0.20 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 50 (95%) as white solid. Example 55 Synthesis of 7-allyl-9-benzyl-2-butoxy-7,9-dihydro-8H-purin-8-one (51): Compound 13 (0.05 g, 0.17 mmol), K₂CO₃ (0.034 g, 0.25 mmol), and allyl bromide (0.017 mL, 0.20 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 51 (93%) as white solid.¹H NMR (400 MHz, Chloroform-d) δ 7.84 (s, 1H), 7.48 (dt, J = 6.8, 2.0 Hz, 2H), 7.29 (dddd, J = 12.0, 6.4, 3.6, 2.0 Hz, 3H), 5.85 (ddt, J = 16.9, 10.4, 5.6 Hz, 1H), 5.28 (dq, J = 4.8, 1.2 Hz, 1H), 5.25 (dq, J = 12.0, 1.2 Hz, 1H), 5.07 (s, 2H), 4.45 (dt, J = 6.0, 1.2 Hz, 2H), 4.31 (t, J = 6.8 Hz, 2H), 1.82 – 1.74 (m, 2H), 1.53-1.43 (m, 2H), 0.96 (t, J = 7.6 Hz, 3H). Example 56 Synthesis of 9-benzyl-2-butoxy-7-(2-hydroxyethyl)-7,9-dihydro-8H-purin-8-one (52): Compound 13 (0.05 g, 0.17 mmol), K₂CO₃ (0.034 g, 0.25 mmol), and 2-bromoethanol (0.014 mL, 0.20 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 52 (92%) as white solid. Example 57 Synthesis of 9-benzyl-2-butoxy-7-(3-hydroxypropyl)-7,9-dihydro-8H-purin-8-one (53): Compound 13 (0.05 g, 0.17 mmol), K₂CO₃ (0.034 g, 0.25 mmol), and 3-bromopropanol (0.018 mL, 0.20 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 53 (95%) as white solid. Example 58 Synthesis of 2-butoxy-7-butyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one (54): Compound 16 (0.05 g, 0.15 mmol), K₂CO₃ (0.031 g, 0.23 mmol), and 1-bromobutane (0.021 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 54 (94%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.85 (s, 1H), 7.45 (d, J = 8.8 Hz, 2H), 6.83 (d, J = 8.8 Hz, 2H), 5.00 (s, 2H), 4.34 (t, J = 6.8 Hz, 2H), 3.81 (t, J = 7.2 Hz, 2H), 3.76 (s, 3H), 1.84 – 1.77 (m, 2H), 1.73-1.66 (m, 2H), 1.55 – 1.47 (m, 2H), 1.40 – 1.31 (m, 2H), 0.98 (t, J = 7.2 Hz, 3H), 0.94 (t, J = 7.2 Hz, 3H). Example 59 Synthesis of 7-allyl-2-butoxy-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one (55): Compound 16 (0.05 g, 0.15 mmol), K₂CO₃ (0.031 g, 0.23 mmol), and allyl bromide (0.017 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20% ethyl acetate in hexane to provide compound 55 (93%) as white solid. Example 60 Synthesis of 2-butoxy-7-(2-hydroxyethyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8- one (56): Compound 16 (0.05 g, 0.15 mmol), K₂CO₃ (0.031 g, 0.23 mmol), and 2-bromoethanol (0.013 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20% ethyl acetate in hexane to provide compound 56 (92%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.99 (s, 1H), 7.44 (d, J = 6.8 Hz, 2H), 6.82 (d, J = 8.4 Hz, 2H), 4.99 (s, 2H), 4.33 (t, J = 6.4 Hz, 2H), 4.00 – 3.91 (m, 4H), 3.75 (s, 3H), 1.83-1.76 (m, 2H), 1.54-1.45 (m, 2H), 0.97 (t, J = 7.2 Hz, 3H). Example 61 Synthesis of 2-butoxy-7-(3-hydroxypropyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin- 8-one (57): Compound 16 (0.05 g, 0.15 mmol), K₂CO₃ (0.031 g, 0.23 mmol), and 3-bromopropanol (0.017 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 57 (95%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.93 (s, 1H), 7.43 (d, J = 8.4 Hz, 2H), 6.82 (d, J = 8.4 Hz, 2H), 5.01 (s, 2H), 4.33 (t, J = 6.8 Hz, 2H), 3.99 (t, J = 6.4 Hz, 2H), 3.75 (s, 3H), 3.56 (t, J = 5.6 Hz, 2H), 1.92-1.86 (m, 2H), 1.83 – 1.76 (m, 2H), 1.54-1.45 (m, 2H), 0.97 (t, J = 7.2 Hz, 3H). Example 62 Synthesis of (R)-2-butoxy-7-((2,2-dimethyl-1,3-dioxolan-4-yl)methyl)-9-(4- methoxybenzyl)-7,9-dihydro-8H-purin-8-one (58): Compound 16 (0.05 g, 0.15 mmol), K₂CO₃ (0.031 g, 0.23 mmol), and(4S)-4-(Bromomethyl)- 2,2-dimethyl-1,3-dioxolane (0.036 g, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 58 (96%) as white solid. 1H NMR (400 MHz, Chloroform-d) δ 8.06 (s, 1H), 7.44 (d, J = 8.8 Hz, 2H), 6.83 (d, J = 8.8 Hz, 2H), 5.01 (d, J = 1.6 Hz, 2H), 4.39 (tt, J = 6.4, 3.2 Hz, 1H), 4.34 (t, J = 6.8 Hz, 2H), 4.11 (dd, J = 8.4, 6.4 Hz, 1H), 4.07 (dd, J = 14.6, 2.8 Hz, 1H), 3.83 (dd, J = 14.8, 6.4 Hz, 1H), 3.76 (s, 3H), 3.74 (dd, J = 8.4, 6.4 Hz, 1H), 1.84-1.77 (m, 2H), 1.55-1.45 (m, 2H), 1.33 (s, 3H), 1.30 (s, 3H), 0.98 (t, J = 7.2 Hz, 3H). Example 63 Synthesis of (R)-2-butoxy-7-(2,3-dihydroxypropyl)-9-(4-methoxybenzyl)-7,9-dihydro- 8H-purin-8-one (59): Compound 58 (0.05 g, 0.11 mmol) was taken in dioxane and 2 ml of 4(N) HCl in dioxane was added to the solution. The reaction mixture was stirred for 2 hours at room temperature. Upon completion of the reaction the organic solvent was evaporated in vacuum and sprinkle of water was added to it. The solution was then neutralized with 4(N) NaOH. The water part was extracted with chloroform and evaporated in reduced pressure. The residue was subjected to flash column chromatography, eluting with 80 % ethyl acetate in hexane to provide compound 59 (85%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 8.04 (s, 1H), 7.42 (d, J = 8.4 Hz, 2H), 6.82 (d, J = 8.8 Hz, 2H), 5.00 (s, 2H), 4.33 (t, J = 6.8 Hz, 2H), 4.07-4.01 (m, 1H), 3.97 (dd, J = 5.2, 2.8 Hz, 2H), 3.76 (s, 3H), 3.65 – 3.53 (m, 2H), 3.16 (s, 2H), 3.05 (s, 2H), 1.83- 1.76 (m, 2H), 1.54-1.44 (m, 2H), 0.98 (t, J = 7.4 Hz, 3H). Example 64 Synthesis of (S)-2-butoxy-7-((2,2-dimethyl-1,3-dioxolan-4-yl)methyl)-9-(4- methoxybenzyl)-7,9-dihydro-8H-purin-8-one (60): Compound 16 (0.05 g, 0.15 mmol), K₂CO₃ (0.031 g, 0.23 mmol), and (4R)-4-(Bromomethyl)- 2,2-dimethyl-1,3-dioxolane (0.036 g, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 60 (96%) as white solid. 1H NMR (400 MHz, Chloroform-d) δ 8.06 (s, 1H), 7.44 (d, J = 8.8 Hz, 2H), 6.83 (d, J = 8.8 Hz, 2H), 5.01 (d, J = 1.6 Hz, 2H), 4.39 (tt, J = 6.4, 3.2 Hz, 1H), 4.34 (t, J = 6.8 Hz, 2H), 4.11 (dd, J = 8.4, 6.4 Hz, 1H), 4.07 (dd, J = 14.6, 2.8 Hz, 1H), 3.83 (dd, J = 14.8, 6.4 Hz, 1H), 3.76 (s, 3H), 3.74 (dd, J = 8.4, 6.4 Hz, 1H), 1.84-1.77 (m, 2H), 1.55-1.45 (m, 2H), 1.33 (s, 3H), 1.30 (s, 3H), 0.98 (t, J = 7.2 Hz, 3H). Example 65 Synthesis of (S)-2-butoxy-7-(2,3-dihydroxypropyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H- purin-8-one (61): Compound 60 (0.05 g, 0.11 mmol) was taken in dioxane and 2 ml of 4(N) HCl in dioxane was added to the solution. The reaction mixture was stirred for 2 hours at room temperature. Upon completion of the reaction the organic solvent was evaporated in vacuum and sprinkle of water was added to it. The solution was then neutralized with 4(N) NaOH. The water part was extracted with chloroform and evaporated in reduced pressure. The residue was subjected to flash column chromatography, eluting with 80 % ethyl acetate in hexane to provide compound 61 (85%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 8.04 (s, 1H), 7.42 (d, J = 8.4 Hz, 2H), 6.82 (d, J = 8.8 Hz, 2H), 5.00 (s, 2H), 4.33 (t, J = 6.8 Hz, 2H), 4.07-4.01 (m, 1H), 3.97 (dd, J = 5.2, 2.8 Hz, 2H), 3.76 (s, 3H), 3.65 – 3.53 (m, 2H), 3.16 (s, 2H), 3.05 (s, 2H), 1.83- 1.76 (m, 2H), 1.54-1.44 (m, 2H), 0.98 (t, J = 7.4 Hz, 3H). Example 66 Synthesis of 2-(3-(2-butoxy-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7- yl)propyl)isoindoline-1,3-dione (62): Compound 16 (0.100 g, 0.30 mmol), K₂CO₃ (0.063 g, 0.46 mmol), andN-(3- Bromopropyl)phthalimide (0.098 g , 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 62 (96%) as white solid. ¹H NMR (400 MHz, Chloroform-d) δ 7.86 (s, 1H), 7.82 (dd, J = 5.2, 3.2 Hz, 2H), 7.71 (dd, J = 5.6, 3.2 Hz, 2H), 7.43 (d, J = 8.8 Hz, 2H), 6.83 (d, J = 8.8 Hz, 2H), 4.98 (s, 2H), 4.32 (t, J = 6.8 Hz, 2H), 3.90 (t, J = 6.8 Hz, 2H), 3.77 (m, 5H), 2.19-2.12 (m, 2H), 1.83 – 1.76 (m, 2H), 1.54 – 1.45(m, 2H), 0.97 (t, J = 7.2 Hz, 3H). Example 67 Synthesis of 7-(3-aminopropyl)-2-butoxy-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8- one (63): Compound 62 (0.50g, 0.09 mmol) was dissolved in 5 ml of EtOH and NH2-NH2. H2O (0.006 mL, 0.19 mmol) was added to it. The reaction mixture was refluxed for 2 hours. After completion of the reaction, a white-coloured precipitate has been formed upon cooling. The precipitate was filtered and the filtrate was evaporated to vacuum. The residue was subjected to flash column chromatography, eluting with 40% CMA (85% chloroform + 10% methanol + 5% ammonia) in chloroform to obtain pure compound 63 (82%) as gummy transparent liquid.¹H NMR (400 MHz, Chloroform-d) δ 7.88 (s, 1H), 7.40 (d, J = 8.8 Hz, 2H), 6.80 (d, J = 8.8 Hz, 2H), 4.97 (s, 2H), 4.31 (t, J = 6.4 Hz, 2H), 3.90 (t, J = 6.4 Hz, 2H), 3.72 (s, 3H), 2.67 (t, J = 6.8 Hz, 2H), 1.84 – 1.73 (m, 4H), 1.52-1.42 (m, 2H), 0.94 (t, J = 7.2 Hz, 3H). Example 68 Synthesis of 2-butoxy-7-(3-chloropropyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8- one (64): Compound 16 (0.100 g, 0.30 mmol), K₂CO₃ (0.063 g, 0.46 mmol), and1-Bromo-3- chloropropane (0.036 mL, 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 64 (93%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.96 (s, 1H), 7.45 (d, J = 8.8 Hz, 2H), 6.83 (d, J = 8.8 Hz, 2H), 5.00 (s, 2H), 4.34 (t, J = 6.8 Hz, 2H), 4.00 (t, J = 6.8 Hz, 2H), 3.76 (s, 3H), 3.55 (t, J = 6.4 Hz, 2H), 2.24- 2.17 (m, 2H), 1.84-1.77 (m, 2H), 1.55-1.45 (m, 2H), 0.98 (t, J = 7.6 Hz, 3H). Example 69 Synthesis of 2-butoxy-9-(4-methoxybenzyl)-7-(3-morpholinopropyl)-7,9-dihydro-8H- purin-8-one (65): Compound 64 (0.05 g, 0.12 mmol),K₂CO₃(0.02g, 0.14 mmol), and morpholine (0.02 ml, 0.24 mmol)were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 65 (80%) as gummy liquid.1H NMR (400 MHz, Chloroform-d) δ 7.91 (s, 1H), 7.45 (d, J = 8.8 Hz, 2H), 6.82 (d, J = 8.8 Hz, 2H), 5.00 (s, 2H), 4.33 (t, J = 6.8 Hz, 2H), 3.89 (t, J = 6.8 Hz, 2H), 3.75 (s, 3H), 3.63 (t, J = 4.8 Hz, 4H), 2.39 – 2.29 (m, 6H), 1.92-1.86 (m, 2H), 1.83 – 1.76 (m, 4H), 1.54-1.47 (m, 2H), 0.98 (t, J = 7.2 Hz, 3H). Example 70 Synthesis of 2-(2-(2-butoxy-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7- yl)ethyl)isoindoline-1,3-dione (66): Compound 16 (0.100 g, 0.30 mmol), K₂CO₃ (0.063 g, 0.46 mmol), andN-(2- Bromoethyl)phthalimide (0.093 g, 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 66 (94%) as white solid. ¹H NMR (400 MHz, Chloroform-d) δ 7.86 (s, 1H), 7.82 (dd, J = 5.2, 3.2 Hz, 2H), 7.71 (dd, J = 5.6, 3.2 Hz, 2H), 7.43 (d, J = 8.8 Hz, 2H), 6.83 (d, J = 8.8 Hz, 2H), 4.98 (s, 2H), 4.32 (t, J = 6.8 Hz, 2H), 3.90 (t, J = 6.8 Hz, 2H), 3.77 (m, 5H), 1.83 – 1.76 (m, 2H), 1.54 – 1.45(m, 2H), 0.97 (t, J = 7.2 Hz, 3H). Example 71 Synthesis of 7-(2-aminoethyl)-2-butoxy-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8- one (67): Compound 66 (0.50g, 0.09 mmol) was dissolved in 5 ml of EtOH and NH₂-NH₂. H₂O (0.006 mL, 0.19 mmol) was added to it. The reaction mixture was refluxed for 2 hours. After completion of the reaction, a white-coloured precipitate has been formed upon cooling. The precipitate was filtered and the filtrate was evaporated to vacuum. The residue was subjected to flash column chromatography, eluting with 30% CMA (85% chloroform + 10% methanol + 5% ammonia) in chloroform to obtain pure compound 67 (82%) as gummy transparent liquid.δ 7.88 (s, 1H), 7.40 (d, J = 8.8 Hz, 2H), 6.80 (d, J = 8.8 Hz, 2H), 4.97 (s, 2H), 4.31 (t, J = 6.4 Hz, 2H), 3.90 (t, J = 6.4 Hz, 2H), 3.72 (s, 3H), 1.84 – 1.73 (m, 4H), 1.52-1.42 (m, 2H), 0.94 (t, J = 7.2 Hz, 3H). Example 72 Synthesis of 7-(4-(bromomethyl)benzyl)-2-butoxy-9-(4-methoxybenzyl)-7,9-dihydro-8H- purin-8-one (68): Compound 16 (0.100 g, 0.30 mmol), K₂CO₃ (0.063 g, 0.46 mmol), and α,α'-Dibromo-p-xylene (0.096 g, 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 68(86%) as white solid. 1H NMR (400 MHz, Chloroform-d) δ 7.62 (s, 1H), 7.46 (d, J = 8.8 Hz, 2H), 7.35 (d, J = 8.0 Hz, 2H), 7.25 (d, J = 8.0 Hz, 3H), 6.84 (d, J = 8.8 Hz, 2H), 5.04 (s, 2H), 4.97 (s, 2H), 4.44 (s, 2H), 4.30 (t, J = 6.8 Hz, 2H), 3.77 (s, 3H), 1.81 – 1.74 (m, 2H), 1.52-1.43 (m, 2H), 0.96 (t, J = 7.6 Hz, 3H). Example 73 Synthesis of 2-butoxy-9-(4-methoxybenzyl)-7-(4-(pyrrolidin-1-ylmethyl)benzyl)-7,9- dihydro-8H-purin-8-one (69): Compound 68 (0.05 g, 0.21 mmol), K₂CO₃ (0.034g, 0.13 mmol), and pyrrolidine (0.043 g, 0.157 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 8% methanol in chloroform, to provide compound 69 as white solid. Example 74 Synthesis of 2-butoxy-7-cyclopentyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one (70): Compound 16 (0.05 g, 0.15 mmol), K₂CO₃ (0.032 g, 0.23 mmol), and Bromocyclopentane (0.018 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 70(94%) as gummy liquid.1H NMR (400 MHz, Chloroform-d) δ 7.90 (s, 1H), 7.45 (d, J = 8.8 Hz, 2H), 6.82 (d, J = 8.8 Hz, 2H), 4.99 (s, 2H), 4.79 (qu, J = 8.6 Hz, 1H), 4.33 (t, J = 6.8 Hz, 2H), 3.75 (s, 3H), 2.04 (qd, J = 11.2, 8.8, 2.8 Hz, 2H), 1.94 – 1.87 (m, 4H), 1.84-1.77 (m, 2H), 1.74-1.65 (m, 2H), 1.54-1.44 (m, 2H), 0.97 (t, J = 7.6 Hz, 3H). Example 75 Synthesis of tert-butyl 3-(2-butoxy-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7- yl)pyrrolidine-1-carboxylate (71): Compound 16 (0.100 g, 0.30 mmol), K₂CO₃ (0.063 g, 0.46 mmol), and tert-butyl 3- bromopyrrolidine-1-carboxylate(0.091 g, 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 8 % methanol in chloroform, to provide compound 71(, 86%) as white solid. Example 76 Synthesis of 2-butoxy-9-(4-methoxybenzyl)-7-(pyrrolidin-3-yl)-7,9-dihydro-8H-purin-8- one (72): Compound 71 (0.05 g, 0.11 mmol) was taken in dioxane and 2 ml of 4(N) HCl in dioxane was added to the solution. The reaction mixture was stirred for 2 hours at room temperature. Upon completion of the reaction the organic solvent was evaporated in vacuum and sprinkle of water was added to it. The solution was then neutralized with 4(N) NaOH. The water part was extracted with chloroform and evaporated in reduced pressure. The residue was subjected to flash column chromatography, eluting with 5% chloroform in methanol to provide compound 72 (, 86%) as gummy liquid. Example 77 Synthesis of 2-butoxy-7-isopropyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one (73): Compound 16 (0.05 g, 0.15 mmol), K₂CO₃ (0.032 g, 0.23 mmol), and 2-Bromopropane (0.017 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 73(, 86%) as white solid. Example 78 Synthesis of 2-butoxy-7-(4-fluorobenzyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8- one (74): Compound 16 (0.05 g, 0.15 mmol), K₂CO₃ (0.032 g, 0.23 mmol), and 4-fluorobenzyl bromide (0.022 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 74 (86%) as white solid.¹H NMR (400 MHz, Chloroform-d) δ 7.62 (s, 1H), 7.46 (d, J = 8.8 Hz, 2H), 7.27 (dd, J = 8.4, 5.2 Hz, 2H), 7.01 (t, J = 8.4 Hz, 2H), 6.84 (d, J = 8.4 Hz, 2H), 5.04 (s, 2H), 4.95 (s, 2H), 4.30 (t, J = 6.8 Hz, 2H), 3.77(s, 3H), 1.81- 1.74 (m, 2H), 1.52-1.43 (m, 2H), 0.96 (t, J = 7.6 Hz, 3H). Example 79 Synthesis of 2-butoxy-7-((5-fluoropyridin-3-yl)methyl)-9-(4-methoxybenzyl)-7,9- dihydro-8H-purin-8-one (75): Compound 16 (0.05 g, 0.15 mmol), K₂CO₃ (0.032 g, 0.23 mmol), and 3-(bromomethyl)-2- chloro-5-fluoropyridine (0.041 mg, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 75 as white solid. Example 80 Synthesis of 2-butoxy-7-cyclopentyl-9-((6-methoxypyridin-3-yl)methyl)-7,9-dihydro-8H- purin-8-one (76): Compound 42 (0.05 g, 0.15 mmol), K₂CO₃ (0.032 g, 0.23 mmol), and Bromocyclopentane (0.018 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 76(94%) as white solid. 1H NMR (400 MHz, Chloroform-d) δ 8.32 (d, J = 2.4 Hz, 1H), 7.92 (s, 1H), 7.75 (dd, J = 8.8, 2.5 Hz, 1H), 6.68 (d, J = 8.4 Hz, 1H), 4.99 (s, 2H), 4.79 (quin, J = 8.8 Hz, 1H), 4.33 (t, J = 6.8 Hz, 2H), 3.89 (s, 3H), 2.08 – 2.00 (m, 2H), 1.94-1.86 (m, 4H), 1.83-1.76 (m, 4H), 1.74-1.68 (m, 2H), 1.54-1.45 (m, 2H), 0.97 (t, J = 7.6 Hz, 3H). Example 81 Synthesis oftert-butyl 3-(2-butoxy-9-((6-methoxypyridin-3-yl)methyl)-8-oxo-8,9- dihydro-7H-purin-7-yl)pyrrolidine-1-carboxylate (77): Compound 42 (0.100 g, 0.30 mmol), K₂CO₃ (0.063 g, 0.46 mmol), and tert-butyl 3- bromopyrrolidine-1-carboxylate (0.091 g, 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 8 % methanol in chloroform, to provide compound 77 (75%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 8.32 (d, J = 2.4 Hz, 1H), 7.73 (dd, J = 8.4, 2.4 Hz, 1H), 6.68 (d, J = 8.4 Hz, 1H), 5.05 (quint, J = 7.6 Hz, 1H), 4.99 (s, 2H), 4.34 (t, J = 6.8 Hz, 2H), 3.89 (s, 3H), 3.46 (q, J = 11.0, 9.5 Hz, 1H), 2.30 (dtd, J = 15.0, 7.9, 4.9 Hz, 2H), 1.80 (dt, J = 14.6, 6.8 Hz, 4H), 1.52 (dd, J = 15.2, 7.5 Hz, 4H), 1.47 (s, 9H), 0.98 (t, J = 7.4 Hz, 3H). Example 82 Synthesis of 2-butoxy-9-((6-methoxypyridin-3-yl)methyl)-7-(pyrrolidin-3-yl)-7,9- dihydro-8H-purin-8-one (78): Compound 77(0.05 g, 0.10 mmol) was taken in dioxane and 2 ml of 4(N) HCl in dioxane was added to the solution. The reaction mixture was stirred for 2 hours at room temperature. Upon completion of the reaction the organic solvent was evaporated in vacuum and sprinkle of water was added to it. The solution was then neutralized with 4(N) NaOH. The water part was extracted with chloroform and evaporated in reduced pressure. The residue was subjected to flash column chromatography, eluting with 5% chloroform in methanol to provide compound 78 (82%) as gummy liquid. Example 83 Synthesis of tert-butyl (4-((2-butoxy-7-butyl-8-oxo-7,8-dihydro-9H-purin-9- yl)methyl)benzyl)carbamate (79): Compound 94 (0.100 g, 0.30 mmol), K₂CO₃ (0.049 g, 0.35 mmol), and 1-Bromobutane(0.04ml, 0.35 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 8 % methanol in chloroform, to provide compound 79. Example 84 Synthesis of 9-(4-(aminomethyl)benzyl)-2-butoxy-7-butyl-7,9-dihydro-8H-purin-8-one (80): Compound 79 (0.05 g, 0.11 mmol) was taken in dioxane and 2 ml of 4(N) HCl in dioxane was added to the solution. The reaction mixture was stirred for 2 hours at room temperature. Upon completion of the reaction the organic solvent was evaporated in vacuum and sprinkle of water was added to it. The solution was then neutralized with 4(N) NaOH. The water part was extracted with chloroform and evaporated in reduced pressure. The residue was subjected to flash column chromatography, eluting with 5% chloroform in methanol to provide compound. Example 85 Synthesis of tert-butyl (4-((2-butoxy-7-cyclopentyl-8-oxo-7,8-dihydro-9H-purin-9- yl)methyl)benzyl)carbamate(81): Compound 32 (0.100 g, 0.30 mmol), K₂CO₃ (0.049 g, 0.35 mmol), and Bromocyclopentane (0.035 ml, 0.35 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 8 % methanol in chloroform, to provide compound 81. Example 86 Synthesis of 9-(4-(aminomethyl)benzyl)-2-butoxy-7-cyclopentyl-7,9-dihydro-8H-purin-8- one (82): Compound 81 (0.05 g, 0.11 mmol) was taken in dioxane and 2 ml of 4(N) HCl in dioxane was added to the solution. The reaction mixture was stirred for 2 hours at room temperature. Upon completion of the reaction the organic solvent was evaporated in vacuum and sprinkle of water was added to it. The solution was then neutralized with 4(N) NaOH. The water part was extracted with chloroform and evaporated in reduced pressure. The residue was subjected to flash column chromatography, eluting with 5% chloroform in methanol to provide compound 82. Example 87 Synthesis of ethyl 2-(butylamino)-4-((3-morpholinopropyl)amino)pyrimidine-5- carboxylate (83): In a pressure tube, 10 ml of dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.139 g, 0.15 mmol) and (±)BINAP (0.189 mg, 0.30 mmol) was added to the toluene one by one and purged for 5-10 minutes. n-Butylamine (0.45 ml, 4.56 mmol) was added to the solution with continuous N₂ purging and the followed by the addition of NaO^tBu (1.1 g, 12.16 mmol). Finally compound 2 (1g, 3.04 mmol) was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 100 °C for 12 hours. Upon completion, the reaction mixture was passed through the celite bed and the filtrate was evaporated in vacuum. The residue was subjected to flash column chromatography, eluting with 80% ethyl acetate in hexane to provide compound 83 (78%) as brown solid.¹H NMR 1H NMR (400 MHz, Chloroform-d) δ 8.50 (s, 1H), 4.25 (q, J = 7.2 Hz, 2H), 3.72 (t, J = 4.4 Hz, 4H), 3.40 (q, J = 6.4 Hz, 2H), 2.48 – 2.40 (m, 6H), 1.84- 1.73 (m, 4H), 1.61-1.53 (m, 2H), 1.44-1.36 (m, 2H), 1.33 (t, J = 7.2 Hz, 3H), 0.94 (t, J = 7.2 Hz, 3H). Example 88 Synthesis of 2-(butylamino)-4-((3-morpholinopropyl)amino)pyrimidine-5-carboxylic acid (84): Compound 83 (0.500 g, 1.39 mmol) in 5 ml THF was added in the pre-stirred solution of potassium hydroxide (4 equivalent) in 5 ml of water. The reaction was then performed according to general procedure C. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 84 (82%) to as brown solid. Example 89 Synthesis of 2-(butylamino)-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one (85): The desired compound 84 was synthesized by general procedure D using Compound 3 (0.500g, 1.48 mmol), Diphenylphosphoryl azide (0.57 ml, 2.65 mmol), Et₃N (0.24 mL, 1.77mmol) in dry 5 mL of DMA. Completion of the reaction was monitored by TLC. Boiling water was poured into the reaction mixture. The aqueous solution was extracted with ethyl acetate and the organic layer was dried over Na₂SO₄ and evaporated under vacuum. The residue was purified by silica gel column chromatography eluting with 2% methanol in chloroform, to provide compound 85 (86%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.80 (s, 1H), 5.00 (s, 1H), 3.90 (t, J = 7.2 Hz, 2H), 3.65 (m, J = 4.8 Hz, 4H), 3.36 (q, J = 6.8 Hz, 2H), 2.48 – 2.39 (m, 6H), 1.96 (qu, J = 7.2 Hz, 2H), 1.61-1.54 (m, 2H), 1.45-1.36 (m, 2H), 0.94 (t, J = 7.2 Hz, 3H). Example 90 Synthesis of ethyl 2-(butylamino)-4-((4-methoxybenzyl)amino)pyrimidine-5-carboxylate (86): Compound 14 (0.500 g, 1.55 mmol), Et₃N (0.32 mL, 2.33 mmol), and n-Butylamine (0.23 mL, 2.33 mmol) were dissolved in 5 mL of dry acetonitrile. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 15 % ethyl acetate in hexane to provide compound 86(84%) as white fluffy solid. Example 91 Synthesis of 2-(butylamino)-4-((4-methoxybenzyl)amino)pyrimidine-5-carboxylic acid (87): Compound 86 (0.500 g, 1.55 mmol) in 5 ml THF was added in the pre-stirred solution of potassium hydroxide (4 equivalent) in 5 ml of water. The reaction was then performed according to general procedure C. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 87 (82%) to as brown solid. Example 92 Synthesis of 2-(butylamino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one (88): Compound 87 (0.500 g, 1.51 mmol) and Diphenylphosphoryl azide (0.58 mL, 2.72 mmol) were taken in dry 5 mL of DMA and Et₃N (0.25 mL, 1.81 mmol) was added to it. The reaction was then performed according to general procedure D. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography eluting with 2% methanol in chloroform, to provide compound 88(86%) as brown solid.1H NMR (400 MHz, DMSO-d6) δ 10.67 (s, 1H), 7.72 (s, 1H), 7.22 (d, J = 8.8 Hz, 2H), 6.83 (d, J = 8.47 Hz, 2H), 6.67 (t, J = 5.6 Hz, 1H), 4.76 (s, 2H), 3.67 (s, 3H), 3.17 (q, J = 6.8 Hz, 2H), 1.47-1.40 (m, 2H), 1.31-1.22 (q, 2H), 0.84 (t, J = 7.6 Hz, 3H). Example 93 Synthesis of ethyl 2-(butylamino)-4-(((6-methoxypyridin-3-yl)methyl)amino)pyrimidine- 5-carboxylate (89): Compound 40 (0.500 g, 1.55 mmol), Et₃N (0.32 mL, 2.33 mmol), and n-Butylamine (0.23 mL, 2.33 mmol) were dissolved in 5 mL of dry acetonitrile. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 15 % ethyl acetate in hexane to provide compound 89(82%) as white fluffy solid. Example 94 Synthesis of 2-(butylamino)-4-(((6-methoxypyridin-3-yl)methyl)amino)pyrimidine-5- carboxylic acid (90): Compound 89 (0.500 g, 1.55 mmol) in 5 ml THF was added in the pre-stirred solution of potassium hydroxide (4 equivalent) in 5 ml of water. The reaction was then performed according to general procedure C. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 90 (84%) to as brown solid.¹H Example 95 Synthesis of 2-(butylamino)-9-((6-methoxypyridin-3-yl)methyl)-7,9-dihydro-8H-purin-8- one (91): Compound 90 (0.500 g, 1.51 mmol) and Diphenylphosphoryl azide (0.58 mL, 2.72 mmol) were taken in dry 5 mL of DMA and Et3N (0.25 mL, 1.81 mmol) was added to it. The reaction was then performed according to general procedure D. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography eluting with 2% methanol in chloroform, to provide compound 91(86%) as white solid. Example 96 Synthesis of ethyl 4-((4-(((tert-butoxycarbonyl)amino)methyl)benzyl)amino)-2- (butylamino)pyrimidine-5-carboxylate (92) Compound 30 (0.500 g, 1.19 mmol), Et3N (0.24 mL, 1.78 mmol), and n-Butylamine (0.18 mL, 1.78 mmol) were dissolved in 5 mL of dry acetonitrile. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 15 % ethyl acetate in hexane to provide compound 92(80%) as white fluffy solid.1H NMR (400 MHz, Chloroform-d) δ 8.52 (s, 1H), 7.29 (d, J = 8.4 Hz, 2H), 7.22 (d, J = 8.0 Hz, 2H), 4.83 (s, 1H), 4.70-4.61 (m, 2H), 4.30-4.22 (m, 4H), 3.44- 3.30 (m, 2H), 1.86-1.79 (m, 2H), 1.57-1.49 (m, 2H), 1.45 (s, 9H), 1.32(t, J = 7.2 Hz, 3H), 0.91 (t, J = 7.2 Hz, 3H). Example 97 Synthesis of 4-((4-(((tert-butoxycarbonyl)amino)methyl)benzyl)amino)-2- (butylamino)pyrimidine-5-carboxylic acid (93): Compound 89 (0.500 g, 1.09 mmol) in 5 ml THF was added in the pre-stirred solution of potassium hydroxide (4 equivalent) in 5 ml of water. The reaction was then performed according to general procedure C. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 93 (80%) to as brown solid. Example 98 Synthesis of 2-(butylamino)-9-((6-methoxypyridin-3-yl)methyl)-7,9-dihydro-8H-purin-8- one (94): Compound 93 (0.500 g, 1.16 mmol) and Diphenylphosphoryl azide (0.45 mL, 2.09 mmol) were taken in dry 5 mL of DMA and Et3N (0.19 mL, 1.39 mmol) was added to it. The reaction was then performed according to general procedure D. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography eluting with 2% methanol in chloroform, to provide compound 94(82%) as white solid.1H NMR (400 MHz, DMSO-d6) δ 10.68 (s, 1H), 7.73 (s, 1H), 7.30 (t, J = 6.0 Hz, 1H), 7.20 (d, J = 8.0 Hz, 2H), 7.13 (d, J = 8.0 Hz, 2H), 6.65 (t, J = 5.6 Hz, 1H), 4.80 (s, 2H), 4.03 (d, J = 6.0 Hz, 2H), 3.16 (q, J = 7.2 Hz, 2H), 1.43 (m, 2H), 1.33 (s, 9H), 1.31-1.21 (m, 2H), 0.84 (t, J = 7.2 Hz, 3H). Example 99 Synthesis of 9-(4-(aminomethyl)benzyl)-2-(butylamino)-7,9-dihydro-8H-purin-8-one (95): Compound 94 (0.05 g, 0.11 mmol) was taken in dioxane and 2 ml of 4(N) HCl in dioxane was added to the solution. The reaction mixture was stirred for 2 hours at room temperature. Upon completion of the reaction the organic solvent was evaporated in vacuum and sprinkle of water was added to it. The solution was then neutralized with 4(N) NaOH. The water part was extracted with chloroform and evaporated in reduced pressure. The residue was subjected to flash column chromatography, eluting with 30% CMA (85% chloroform + 10% methanol + 5% ammonia) in chloroform to obtain pure compound 95 (87%) as light-brown solid.1H NMR (400 MHz, DMSO-d6) δ 7.73 (s, 1H), 7.22 (d, J = 4.0 Hz, 4H), 6.65 (t, J = 5.6 Hz, 1H), 4.80 (s, 2H), 3.63 (s, 2H), 3.16 (q, J = 6.8 Hz, 2H), 1.47-1.39 (m, 2H), 1.31-1.22 (m, 2H), 0.83 (t, J = 7.6 Hz, 3H). Example 100 Synthesis of tert-butyl (4-((2-(butylamino)-7-cyclopentyl-8-oxo-7,8-dihydro-9H-purin-9- yl)methyl)benzyl)carbamate(96): Compound 94 (0.100 g, 0.30 mmol), K₂CO₃ (0.049 g, 0.35 mmol), and Bromocyclopentane (0.035 ml, 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 8 % methanol in chloroform, to provide compound 96(92%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.79 (s, 1H), 7.45 (d, J = 8.0 Hz, 2H), 7.22 (d, J = 8.0 Hz, 2H), 4.96 (s, 2H), 4.89 (t, J = 6.0 Hz, 1H), 4.83-4.73 (m, 2H), 4.27 (d, J = 5.6 Hz, 2H), 3.41 – 3.36 (m, 2H), 2.07 – 1.97 (m, 2H), 1.93 – 1.84 (m, 4H), 1.74-1.78 (s, 2H), 1.62 – 1.55 (m, 3H), 1.44 (s, 9H), 0.95 (d, J = 7.6 Hz, 3H). Example 101 Synthesis of 9-(4-(aminomethyl)benzyl)-2-(butylamino)-7-cyclopentyl-7,9-dihydro-8H- purin-8-one (97): Compound 96(0.05 g, 0.11 mmol) was taken in dioxane and 2 ml of 4(N) HCl in dioxane was added to the solution. The reaction mixture was stirred for 2 hours at room temperature. Upon completion of the reaction the organic solvent was evaporated in vacuum and sprinkle of water was added to it. The solution was then neutralized with 4(N) NaOH. The water part was extracted with chloroform and evaporated in reduced pressure. The residue was subjected to flash column chromatography, eluting with 5% chloroform in methanol to provide compound 97(86%) as gummy liquid.1H NMR (400 MHz, Chloroform-d) δ 7.79 (s, 1H), 7.46 (d, J = 8.0 Hz, 2H), 7.26 (d, J = 8.0 Hz, 3H), 4.97 (s, 2H), 4.77 (qu, J = 8.8 Hz, 1H), 3.83 (s, 2H), 3.39 (q, J = 6.8 Hz, 2H), 2.06 – 1.98 (m, 2H), 1.94-1.90 (m, 2H), 1.85-1.81 (m, 2H), 1.75 – 1.65 (m, 2H), 1.63-1.55 (m, 2H), 1.47-1.37 (m, 2H), 0.95 (t, J = 7.2 Hz, 3H). Example 102 Synthesis of tert-butyl (4-((2-(butylamino)-7-cyclopentyl-8-oxo-7,8-dihydro-9H-purin-9- yl)methyl)benzyl)carbamate(98) Compound 94 (0.100 g, 0.30 mmol), K₂CO₃ (0.049 g, 0.35 mmol), and tert-butyl 3- bromopyrrolidine-1-carboxylate (0.88g, 0.35 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 8 % methanol in chloroform, to provide compound 98. Example 103 Synthesis of 9-(4-(aminomethyl)benzyl)-2-(butylamino)-7-cyclopentyl-7,9-dihydro-8H- purin-8-one (99): Compound 98 (0.05 g, 0.11 mmol) was taken in dioxane and 2 ml of 4(N) HCl in dioxane was added to the solution. The reaction mixture was stirred for 2 hours at room temperature. Upon completion of the reaction the organic solvent was evaporated in vacuum and sprinkle of water was added to it. The solution was then neutralized with 4(N) NaOH. The water part was extracted with chloroform and evaporated in reduced pressure. The residue was subjected to flash column chromatography, eluting with 5% chloroform in methanol to provide compound 99. Example 104 Synthesis of 7-butyl-2-(butylamino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one (100): Compound 88 (0.05 g, 0.15 mmol), K₂CO₃ (0.031 g, 0.23 mmol), and 1-bromobutane (0.021 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 100 (95%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.72 (s, 1H), 7.42 (d, J = 8.8 Hz, 2H), 6.82 (d, J = 8.0 Hz, 2H), 4.93 (s, 2H), 3.77-3.74 (m, 5H), 3.39 (q, J = 7.2 Hz, 2H), 1.70 – 1.63 (m, 2H), 1.62 – 1.55 (m, 2H), 1.46 – 1.38 (m, 2H), 1.37 – 1.29 (m, 2H), 0.94 (dt, J = 12.4, 7.8 Hz, 6H). Example 105 Synthesis of 2-(butylamino)-7-cyclopentyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8- one (101): Compound 88 (0.05 g, 0.15 mmol), K₂CO₃ (0.032 g, 0.23 mmol), and Bromocyclopentane (0.018 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 101 (, 86%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.79 (s, 1H), 7.45 (d, J = 8.4 Hz, 2H), 6.83 (d, J = 8.8 Hz, 2H), 4.92 (s, 2H), 4.86 (t, J = 5.6 Hz, 1H), 4.77 (qu, J = 8.0 Hz, 1H), 3.77 (s, 3H), 3.40 (q, J = 6.8 Hz, 2H), 2.05-1.98 (m, 2H), 1.93 – 1.83 (m, 4H), 1.73-1.67 (m, 2H), 1.63-1.56 (m, 2H), 1.47-1.83 (m, 2H), 0.96 (t, J = 7.6 Hz, 3H). Example 106 Synthesis of tert-butyl 3-(2-(butylamino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H- purin-7-yl)pyrrolidine-1-carboxylate (102): Compound 88 (0.100 g, 0.30 mmol), K₂CO₃ (0.063 g, 0.46 mmol), and tert-butyl 3- bromopyrrolidine-1-carboxylate (0.091 g, 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 8 % methanol in chloroform, to provide compound 102. Example 107 Synthesis of 2-(butylamino)-9-(4-methoxybenzyl)-7-(pyrrolidin-3-yl)-7,9-dihydro-8H- purin-8-one (103): Compound 102 (0.05 g, 0.11 mmol) was taken in dioxane and 2 ml of 4(N) HCl in dioxane was added to the solution. The reaction mixture was stirred for 2 hours at room temperature. Upon completion of the reaction the organic solvent was evaporated in vacuum and sprinkle of water was added to it. The solution was then neutralized with 4(N) NaOH. The water part was extracted with chloroform and evaporated in reduced pressure. The residue was subjected to flash column chromatography, eluting with 5% chloroform in methanol to provide compound 103. Example 108 Synthesis of 2-(butylamino)-7-isopropyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8- one (104): Compound 88 (0.05 g, 0.15 mmol), K₂CO₃ (0.032 g, 0.23 mmol), and 2-Bromopropane (0.017 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 104 (96%) as gummy liquid.1H NMR (400 MHz, Chloroform- d) δ 7.84 (s, 1H), 7.42 (d, J = 8.8 Hz, 2H), 6.81 (d, J = 8.8 Hz, 2H), 4.93 (d, J = 6.0 Hz, 1H), 4.91 (s, 2H), 4.64 (quint, J = 6.8 Hz, 1H), 3.75 (s, 3H), 3.40 – 3.35 (m, 2H), 1.61-1.54 (m, 2H), 1.41 (s, 3H), 1.40 (s, 3H), 0.94 (t, J = 7.6 Hz, 3H). Example 109 Synthesis of 2-(butylamino)-7-(4-fluorobenzyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H- purin-8-one (105): Compound 88 (0.05 g, 0.15 mmol), K₂CO₃ (0.032 g, 0.23 mmol), and 4-fluorobenzyl bromide (0.022 mL, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 105 (95%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.48 (s, 1H), 7.45 (d, J = 8.8 Hz, 2H), 7.28 – 7.23 (m, 2H), 7.03 – 6.97 (m, 2H), 6.84 (d, J = 8.8 Hz, 2H), 4.96 (s, 2H), 4.90 (s, 2H), 3.78 (s, 3H), 3.35 (d, J = 6.8 Hz, 2H), 1.61-1.53 (m, 2H), 1.45-1.36 (m, 2H), 0.94 (t, J = 7.2 Hz, 3H). Example 110 Synthesis of 2-(butylamino)-7-((5-fluoropyridin-3-yl)methyl)-9-(4-methoxybenzyl)-7,9- dihydro-8H-purin-8-one (106): Compound 88 (0.05 g, 0.15 mmol), K₂CO₃ (0.032 g, 0.23 mmol), and 3-(bromomethyl)-2- chloro-5-fluoropyridine (0.041 mg, 0.18 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 106 (95%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 8.41 (d, J = 2.4 Hz, 2H), 7.55 (s, 1H), 7.44 (d, J = 8.8 Hz, 2H), 7.32 (dt, J = 8.4, 2.0 Hz, 1H), 6.85 (d, J = 8.8 Hz, 2H), 4.98 (s, 2H), 4.97 (s, 2H), 3.78 (s, 3H), 3.38 (q, J = 7.2 Hz, 2H), 1.62-1.54 (m, 2H), 1.46-1.36 (m, 2H), 0.95 (t, J = 7.6 Hz, 3H). Example 111 Synthesis of 2-(3-(2-butylamino-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7- yl)propyl)isoindoline-1,3-dione (107): Compound 88 (0.100 g, 0.30 mmol), K₂CO₃ (0.063 g, 0.46 mmol), andN-(3- Bromopropyl)phthalimide (0.098 g , 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 107 (94%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.81 (dd, J = 5.6, 3.2 Hz, 2H), 7.70 – 7.68 (m, 3H), 7.40 (d, J = 8.8 Hz, 2H), 6.81 (d, J = 8.8 Hz, 2H), 5.00 (t, J = 4.0 Hz, 1H), 4.90 (s, 2H), 3.84 (d, J = 7.2 Hz, 2H), 3.76-3.73 (m, 5H), 3.38 (q, J = 7.2 Hz, 2H), 2.15-2.08 (m, 2H), 1.61-1.54 (m, 2H), 1.46-1.36 (m, 2H), 0.95 (t, J = 7.2 Hz, 3H). Example 112 Synthesis of 7-(3-aminopropyl)-2-butylamino-9-(4-methoxybenzyl)-7,9-dihydro-8H- purin-8-one (108): Compound 107(0.50g, 0.09 mmol) was dissolved in 5 ml of EtOH and NH₂-NH₂. H₂O (0.01 mL, 0.34 mmol) was added to it. The reaction mixture was refluxed for 2 hours. After completion of the reaction, a white-coloured precipitate has been formed upon cooling. The precipitate was filtered and the filtrate was evaporated to vacuum. The residue was subjected to flash column chromatography, eluting with 40% CMA (85% chloroform + 10% methanol + 5% ammonia) in chloroform to obtain pure compound 108 (86%) as gummy transparent liquid.1H NMR (400 MHz, Chloroform-d) δ 7.77 (s, 1H), 7.42 (d, J = 8.4 Hz, 2H), 6.83 (d, J = 8.8 Hz, 2H), 4.94 (s, 2H), 4.90 (t, J = 5.6 Hz, 1H), 3.88 (t, J = 6.4 Hz, 2H), 3.76 (s, 3H), 3.40 (q, J = 6.8 Hz, 2H), 2.70 (t, J = 6.8 Hz, 2H), 1.86-1.79 (m, 2H), 1.63-1.56 (m, 2H), 1.47-1.38 (m, 2H), 0.96 (t, J = 7.6 Hz, 3H). Example 113 Synthesis of 2-(2-(2-butylamino-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7- yl)ethyl)isoindoline-1,3-dione (109): Compound 88 (0.100 g, 0.30 mmol), K₂CO₃ (0.063 g, 0.46 mmol), andN-(2- Bromoethyl)phthalimide (0.093 g, 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 66 (, 86%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.75 (dd, J = 5.2, 3.2 Hz, 2H), 7.71 (s, 1H), 7.67 (dd, J = 5.2, 3.2 Hz, 2H), 7.32 (d, J = 8.8 Hz, 2H), 6.78 (d, J = 8.4 Hz, 2H), 4.85 (s, 2H), 4.08 – 4.03 (m, 2H), 4.01 – 3.96 (m, 2H), 3.76 (s, 3H), 3.35 (q, J = 7.2 Hz, 2H), 1.59-1.52 (m, 2H), 1.44- 1.35 (m, 2H), 0.94 (t, J = 7.2 Hz, 3H). Example 114 Synthesis of 7-(2-aminoethyl)-2-butylamino-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin- 8-one (110): Compound 109 (0.50g, 0.09 mmol) was dissolved in 5 ml of EtOH and NH2-NH2. H2O (0.01 mL, 0.34 mmol) was added to it. The reaction mixture was refluxed for 2 hours. After completion of the reaction, a white-coloured precipitate has been formed upon cooling. The precipitate was filtered and the filtrate was evaporated to vacuum. The residue was subjected to flash column chromatography, eluting with 30% CMA (85% chloroform + 10% methanol + 5% ammonia) in chloroform to obtain pure compound 110 (, 86%) as gummy transparent liquid.1H NMR (400 MHz, Chloroform-d) δ 7.79 (s, 1H), 7.42 (d, J = 8.8 Hz, 2H), 6.83 (d, J = 8.8 Hz, 2H), 4.97 (t, J = 4.8 Hz, 1H), 4.94 (s, 2H), 3.83 (t, J = 6.0 Hz, 2H), 3.77 (s, 3H), 3.40 (q, J = 7.2 Hz, 2H), 3.02 (t, J = 6.0 Hz, 2H), 1.63-1.56 (m, 2H), 1.47-1.38 (m, 2H), 0.96 (t, J = 7.2 Hz, 3H). Example 115 Synthesis of 7-(4-(bromomethyl)benzyl)-2-butylamino-9-(4-methoxybenzyl)-7,9-dihydro- 8H-purin-8-one (111): Compound 88 (0.100 g, 0.30 mmol), K₂CO₃ (0.063 g, 0.46 mmol), and α,α'-Dibromo-p-xylene (0.096 g, 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 111 (, 86%) as white solid. Example 116 Synthesis of 2-butylamino-9-(4-methoxybenzyl)-7-(4-(pyrrolidin-1-ylmethyl)benzyl)-7,9- dihydro-8H-purin-8-one (112): Compound 111 (0.05 g, 0.21 mmol), K₂CO₃ (0.034g, 0.13 mmol), and pyrrolidine (0.043 g, 0.157 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 8 % methanol in chloroform, to provide compound 112 (92%). Example 117 Synthesis of 2-butylamino-7-(3-chloroethyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin- 8-one (113): Compound 88 (0.100 g, 0.30 mmol), K₂CO₃ (0.063 g, 0.46 mmol), and1-Bromo-2- chloroethane (0.030 mL, 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 113. Example 118 Synthesis of 2-(butylamino)-7-(2-(dimethylamino)ethyl)-9-(4-methoxybenzyl)-7,9- dihydro-8H-purin-8-one (114): Compound 113(0.05 g, 0.21 mmol), K₂CO₃ (0.034g, 0.13 mmol), and dimethylamine (0.043 ml, 0.157 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 114(90%) as brown-coloured gummy liquid. Example 119 Synthesis of 2-(butylamino)-9-(4-methoxybenzyl)-7-(2-(methylamino)ethyl)-7,9-dihydro- 8H-purin-8-one (115): Compound 113 (0.05 g, 0.21 mmol), K₂CO₃ (0.034g, 0.13 mmol), and methylamine (0.042 ml, 0.157 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 115 (92%) as brown-coloured gummy liquid. Example 120 Synthesis of 2-(butylamino)-7-(3-chloropropyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H- purin-8-one (116): Compound 88 (0.100 g, 0.30 mmol), K₂CO₃ (0.063 g, 0.46 mmol), and1-Bromo-3- chloropropane (0.036 mL, 0.36 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 116 (92%) as white solid. Example 121 Synthesis of 2-(butylamino)-9-(4-methoxybenzyl)-7-(3-piperidinopropyl)-7,9-dihydro- 8H-purin-8-one (117): Compound 116 (0.05 g, 0.21 mmol), K₂CO₃ (0.034g, 0.13 mmol), and piperidine (0.043 ml, 0.157 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 117(90 %) as white solid. Example 122 Synthesis of 2-(butylamino)-9-(4-methoxybenzyl)-7-(3-(5-methyl-2,5- diazabicyclo[2.2.1]heptan-2-yl)propyl)-7,9-dihydro-8H-purin-8-one (118): Compound 116(0.05 g, 0.21 mmol), K₂CO₃ (0.034g, 0.13 mmol), and 2-Methyl-2,5- diazabicyclo[2.2.1]heptane dihydrobromide(0.043 g, 0.157 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 118(85%) as white solid. Example 123 Synthesis of 2-(butylamino)-7-cyclopentyl-7,9-dihydro-8H-purin-8-one(119): Compound 101 (0.100 g, 0.25 mmol) was taken in a 10 ml RB. TFMSA (0.11 ml, 1.26 mmol) was added to the solid sample followed by the addition of TFA (0.019 ml, 0.25 mmol) at 0 °C.The reaction mixture was stirred for 2 hours at room temperature. After the completion of the reaction, the reaction mixture was neutralized with 4 (N) NaOH. The water part was extracted with chloroform for 3 times. The organic solvent was evaporated under vacuum and the residue was purified by flash column chromatography, with 25% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform, to provide compound 119 (96%) as brown solid. Example 124 Synthesis of 2-(butylamino)-7-cyclopentyl-9-(3-methoxybenzyl)-7H-purin-8(9H)-one (120): Compound 119 (0.05 g, 0.18 mmol), K₂CO₃ (0.038g, 0.27 mmol), and 3-Methoxybenzyl bromide(0.038 ml, 0.27 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 8 hours at 75 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 120(92%) as off- white solid. Example 125 Synthesis of 9-(4-bromobenzyl)-2-(butylamino)-7-cyclopentyl-7H-purin-8(9H)-one(121): Compound 119 (0.05 g, 0.18 mmol), K₂CO₃ (0.038g, 0.27 mmol), and 4-Bromobenzyl Bromide(0.068 g, 0.27 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 8 hours at 75 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 121 (94%) as off- white solid. Example 126 Synthesis of 2-(butylamino)-7-cyclopentyl-9-(naphthalen-1-ylmethyl)-7H-purin-8(9H)- one (122): Compound 119 (0.05 g, 0.18 mmol), K₂CO₃ (0.038g, 0.27 mmol), and1- (Bromomethyl)naphthalene (0.060 g, 0.27 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 8 hours at 75 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 122 (93%) as off-white solid. Example 127 Synthesis of 9-([1,1'-biphenyl]-4-ylmethyl)-2-(butylamino)-7-cyclopentyl-7H-purin- 8(9H)-one (123): Compound 119 (0.05 g, 0.18 mmol), K₂CO₃ (0.038g, 0.27 mmol), and4- Bromomethylbiphenyl(0.067 g, 0.27 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 8 hours at 75 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 123 (95%) as off- white solid. Example 128 Synthesis of 2-(butylamino)-7-cyclopentyl-9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan- 2-yl)benzyl)-7H-purin-8(9H)-one (124): In a pressure tube, 10 ml of dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.005 g, 0.005 mmol) and (±)BINAP (0.007 g, 0.011 mmol) was added to the toluene one by one and purged for 5-10 minutes.2-Methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide (0.031 g, 4.56 mmol) was added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu (0.043 g, 0.023 mmol). Finally compound 121 (0.05 g, 0.112 mmol) was added to the pre- stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours. Upon completion, the reaction mixture was passed through the celite bed and the filtrate was evaporated in vacuum. The residue was subjected to flash column chromatography, eluting with 45% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform to provide compound 124(78%) as brown solid. Example 129 Synthesis of tert-butyl 4-(4-((2-(butylamino)-7-cyclopentyl-8-oxo-7H-purin-9(8H)- yl)methyl)phenyl)piperazine-1-carboxylate (125): In a pressure tube, 10 ml of dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.005 g, 0.005 mmol) and (±)BINAP (0.007 g, 0.011 mmol) was added to the toluene one by one and purged for 5-10 minutes.1-Boc-piperazine(0.020 g, 0.112 mmol) was added to the solution with continuous N₂ purging and the followed by the addition of NaO^tBu (0.043 g, 0.023 mmol). Finally compound 121 (0.05 g, 0.112 mmol) was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 100 °C for 12 hours. Upon completion, the reaction mixture was passed through the celite bed and the filtrate was evaporated in vacuum. The residue was subjected to flash column chromatography, eluting with 25% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform to provide compound 124 (82%) as brown solid. Example 130 Synthesis of 2-(butylamino)-7-cyclopentyl-9-(4-(piperazin-1-yl)benzyl)-7H-purin-8(9H)- one (126): Compound 125 (0.050 g, 0.25 mmol) was taken in 2 ml of DCM. TFA (0.11 ml, 1.26 mmol) was added to the solution at 0 °C. The reaction mixture was stirred for 2 hours at room temperature. After the completion of the reaction, the reaction mixture was neutralized with 4 (N) NaOH. The water part was extracted with chloroform for 3 times. The organic solvent was evaporated under vacuum and the residue was purified by flash column chromatography, with 75% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform, to provide compound 126(86%) as brown solid. Example 131 Synthesis of 2-(butylamino)-7-cyclopentyl-9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan- 2-yl)benzyl)-7H-purin-8(9H)-one (127): In a pressure tube, 10 ml of dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.005 g, 0.005 mmol) and (±)BINAP (0.007 g, 0.011 mmol) was added to the toluene one by one and purged for 5-10 minutes. Pyrollidine (0.009 ml, 0.112 mmol) was added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu (0.043 g, 0.023 mmol). Finally compound 121 (0.05 g, 0.112 mmol) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours. Upon completion, the reaction mixture was passed through the celite bed and the filtrate was evaporated in vacuum. The residue was subjected to flash column chromatography, eluting with 45% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform to provide compound 127(78%) as brown solid. Example 132 Synthesis of 9-(4-(bromomethyl)benzyl)-2-(butylamino)-7-cyclopentyl-7H-purin-8(9H)- one (128): Compound 119 (0.100 g, 0.36 mmol), K₂CO₃ (0.076g, 0.54 mmol), andα,α′-Dibromo-p- xylene(0.144 g, 0.54 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 8 hours at 75 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 45% ethyl acetate in hexane, to provide compound 128(94%) as off- white solid. Example 133 Synthesis of 2-(butylamino)-7-cyclopentyl-9-(4-((5-methyl-2,5-diazabicyclo[2.2.1]heptan- 2-yl)methyl)benzyl)-7H-purin-8(9H)-one (129): Compound 128 (0.05 g, 0.11 mmol), K₂CO₃ (0.022g, 0.16 mmol), and2-Methyl-2,5- diazabicyclo[2.2.1]heptane dihydrobromide (0.045 g, 0.16 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 8 hours at 75 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 55% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform, to provide compound 129(87%) as off-white solid. Example 134 Synthesis of 2-(butylamino)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)- 7H-purin-8(9H)-one(130): Compound 118 (0.100 g, 0.21 mmol) was taken in a 10 ml RB. TFMSA (0.09 ml, 1.04 mmol) was added to the solid sample followed by the addition of TFA (0.015 ml, 0.21mmol) at 0 °C. The reaction mixture was stirred for 2 hours at room temperature. After the completion of the reaction, the reaction mixture was neutralized with 4 (N) NaOH. The water part was extracted with chloroform for 3 times. The organic solvent was evaporated under vacuum and the residue was purified by flash column chromatography, with 95% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform, to provide compound 130(94%) as brown solid. Example 135 Synthesis of 9-(4-bromobenzyl)-2-(butylamino)-7-(3-(5-methyl-2,5- diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H-purin-8(9H)-one (131): Compound 119 (0.05 g, 0.14 mmol), K₂CO₃ (0.029 g, 0.21 mmol), and 4-Bromobenzyl Bromide (0.052 g, 0.21 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 8 hours at 75 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 131 (94%) as off- white solid. Example 136 Synthesis of ethyl 4-((4-methoxybenzyl)amino)-2-(propylamino)pyrimidine-5- carboxylate (132): Compound 14 (0.500 g, 1.55 mmol), Et3N (0.32 mL, 2.33 mmol), andPropylamine (0.19 mL, 2.33 mmol) were dissolved in 5 mL of dry acetonitrile. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 15 % ethyl acetate in hexane to provide compound 132(84%) as white fluffy solid. Example 137 Synthesis of 4-((4-methoxybenzyl)amino)-2-(propylamino)pyrimidine-5-carboxylic acid (133): Compound 132 (0.500 g, 1.45 mmol) in 5 ml THF was added in the pre-stirred solution of potassium hydroxide (4 equivalent) in 5 ml of water. The reaction was then performed according to general procedure C. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 133 (77%) to as brown solid. Example 138 Synthesis of 9-(4-methoxybenzyl)-2-(propylamino)-7H-purin-8(9H)-one (134): Compound 133 (0.500 g, 1.58 mmol) and Diphenylphosphoryl azide (0.61 mL, 2.84 mmol) were taken in dry 5 mL of DMA and Et₃N (0.26 mL, 1.89 mmol) was added to it. The reaction was then performed according to general procedure D. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography eluting with 2% methanol in chloroform, to provide compound 134(85%) as white solid. Example 139 Synthesis of 7-cyclopentyl-9-(4-methoxybenzyl)-2-(propylamino)-7H-purin-8(9H)-one (135): Compound 134 (0.05 g, 0.16 mmol), K₂CO₃ (0.033 g, 0.24 mmol), and Bromocyclopentane (0.019 mL, 0.19 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 135(96%) as white solid. Example 140 Synthesis of 7-(3-chloropropyl)-9-(4-methoxybenzyl)-2-(propylamino)-7H-purin-8(9H)- one (136): Compound 135 (0.100 g, 0.32 mmol), K₂CO₃ (0.066 g, 0.48 mmol), and1-Bromo-3- chloropropane (0.038 mL, 0.38 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 136 (95%) as white solid. Example 141 Synthesis of 9-(4-methoxybenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)propyl)-2-(propylamino)-7H-purin-8(9H)-one (137): Compound 136 (0.05 g, 0.13 mmol), K₂CO₃ (0.027g, 0.19 mmol), and piperidine (0.053 g, 0.19 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 137 (92%) as white solid. Example 142 Synthesis of 7-cyclopentyl-2-(propylamino)-7H-purin-8(9H)-one(138): Compound 135 (0.100 g, 0.26 mmol) was taken in a 10 ml RB. TFMSA (0.12 ml, 1.31 mmol) was added to the solid sample followed by the addition of TFA (0.02 ml, 0.26 mmol) at 0 °C. The reaction mixture was stirred for 3 hours at room temperature. After the completion of the reaction, the reaction mixture was neutralized with 4 (N) NaOH. The water part was extracted with chloroform for 3 times. The organic solvent was evaporated under vacuum and the residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 138 (98%) as brown solid. Example 143 Synthesis of 9-(4-bromobenzyl)-7-cyclopentyl-2-(propylamino)-7H-purin-8(9H)-one (139): Compound 138 (0.100 g, 0.38 mmol), K₂CO₃ (0.079 g, 0.57 mmol), and 4-Bromobenzyl bromide (0.143 g, 0.57 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 55% ethyl acetate in hexane, to provide compound 139(80%) as white solid. Example 144 Synthesis of 7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-2-(propylamino)- 7H-purin-8(9H)-one(140): Compound 135 (0.100 g, 0.21 mmol) was taken in a 10 ml RB. TFMSA (0.094 ml, 1.07 mmol) was added to the solid sample followed by the addition of TFA (0.016 ml, 0.21 mmol) at 0 °C. The reaction mixture was stirred for 3 hours at room temperature. After the completion of the reaction, the reaction mixture was neutralized with 4 (N) NaOH. The water part was extracted with chloroform for 3 times. The organic solvent was evaporated under vacuum and the residue was purified by flash column chromatography, with 95% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform, to provide compound 140 (98%) as brown solid. Example 145 Synthesis of 9-(4-bromobenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)propyl)-2-(propylamino)-7H-purin-8(9H)-one (141): Compound 140 (0.100 g, 0.29 mmol), K₂CO₃ (0.060 g, 0.43 mmol), and 4-Bromobenzyl bromide (0.109 g, 0.43 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 55% ethyl acetate in hexane, to provide compound 141 (81%) as white solid. Example 146 Synthesis of 7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-2-(propylamino)- 9-(4-(trifluoromethyl)benzyl)-7H-purin-8(9H)-one (142): Compound 140 (0.50 g, 0.15 mmol), K₂CO₃ (0.030 g, 0.22 mmol), and 4- (Trifluoromethyl)benzyl Bromide (0.044 ml, 0.22 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 55% ethyl acetate in hexane, to provide compound 142(88%) as white solid. Example 147 Synthesis of 9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7-(3-(5-methyl- 2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-2-(propylamino)-7H-purin-8(9H)-one (143): In a pressure tube, 10 ml of dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.005 g, 0.004 mmol) and (±)BINAP (0.006 g, 0.009 mmol) was added to the toluene one by one and purged for 5-10 minutes.2-Methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide (0.027 , 0.097 mmol) was added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu (0.037 g, 0.388 mmol). Finally compound 141 (0.05 g, 0.097 mmol) was added to the pre- stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours. Upon completion, the reaction mixture was passed through the celite bed and the filtrate was evaporated in vacuum. The residue was subjected to flash column chromatography, eluting with 45% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform to provide compound 143(82%) as brown solid. Example 148 Synthesis of ethyl 2-(ethylamino)-4-((4-methoxybenzyl)amino)pyrimidine-5-carboxylate (144): Compound 14 (0.500 g, 1.55 mmol), Et3N (0.32 mL, 2.33 mmol), andethylamine (0.15 mL, 2.33 mmol) were dissolved in 5 mL of dry acetonitrile. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 15 % ethyl acetate in hexane to provide compound 144(92%) as white fluffy solid. Example 149 Synthesis of 4-((4-methoxybenzyl)amino)-2-(propylamino)pyrimidine-5-carboxylic acid (145): Compound 144 (0.500 g, 1.51 mmol) in 5 ml THF was added in the pre-stirred solution of potassium hydroxide (4 equivalent) in 5 ml of water. The reaction was then performed according to general procedure C. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 145 (84%) to as brown solid. Example 150 Synthesis of 2-(ethylamino)-9-(4-methoxybenzyl)-7H-purin-8(9H)-one (146): Compound 145 (0.500 g, 1.65 mmol) and Diphenylphosphoryl azide (0.64 ml, 2.97 mmol) were taken in dry 5 mL of DMA and Et₃N (0.28 mL, 1.98 mmol) was added to it. The reaction was then performed according to general procedure D. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography eluting with 2% methanol in chloroform, to provide compound 146(86%) as white solid. Example 151 Synthesis of 7-cyclopentyl-2-(ethylamino)-9-(4-methoxybenzyl)-7H-purin-8(9H)-one (147): Compound 146 (0.05 g, 0.16 mmol), K₂CO₃ (0.035 g, 0.25 mmol), and Bromocyclopentane (0.020 mL, 0.20 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 147(92%) as white solid. Example 152 Synthesis of 7-(3-chloropropyl)-2-(ethylamino)-9-(4-methoxybenzyl)-7H-purin-8(9H)- one (148): Compound 147 (0.100 g, 0.32 mmol), K₂CO₃ (0.070 g, 0.50 mmol), and1-Bromo-3- chloropropane (0.040 mL, 0.40 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 148(94%) as white solid. Example 153 Synthesis of 2-(ethylamino)-9-(4-methoxybenzyl)-7-(3-(5-methyl-2,5- diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H-purin-8(9H)-one (149): Compound 148 (0.05 g, 0.13 mmol), K₂CO₃ (0.027g, 0.19 mmol), and 2-Methyl-2,5- diazabicyclo[2.2.1]heptane dihydrobromide(0.053 g, 0.19 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 149(90%) as gummy liquid. Example 154 Synthesis of 7-cyclopentyl-2-(ethylamino)-7H-purin-8(9H)-one (150): Compound 147(0.100 g, 0.26 mmol) was taken in a 10 ml RB. TFMSA (0.12 ml, 1.31 mmol) was added to the solid sample followed by the addition of TFA (0.02 ml, 0.26 mmol) at 0 °C. The reaction mixture was stirred for 3 hours at room temperature. After the completion of the reaction, the reaction mixture was neutralized with 4 (N) NaOH. The water part was extracted with chloroform for 3 times. The organic solvent was evaporated under vacuum and the residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 150(98%) as brown solid. Example 155 Synthesis of 9-(4-bromobenzyl)-7-cyclopentyl-2-(ethylamino)-7H-purin-8(9H)-one (151): Compound 150 (0.100 g, 0.38 mmol), K₂CO₃ (0.079 g, 0.57 mmol), and 4-Bromobenzyl bromide (0.145 g, 0.59 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 55% ethyl acetate in hexane, to provide compound 151 (82%) as white solid. Example 156 Synthesis of 2-(ethylamino)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)- 7H-purin-8(9H)-one (152): Compound 149(0.100 g, 0.21 mmol) was taken in a 10 ml RB. TFMSA (0.094 ml, 1.07 mmol) was added to the solid sample followed by the addition of TFA (0.016 ml, 0.21 mmol) at 0 °C. The reaction mixture was stirred for 3 hours at room temperature. After the completion of the reaction, the reaction mixture was neutralized with 4 (N) NaOH. The water part was extracted with chloroform for 3 times. The organic solvent was evaporated under vacuum and the residue was purified by flash column chromatography, with 95% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform, to provide compound 152(96%) as brown solid. Example 157 Synthesis 9-(4-bromobenzyl)-2-(ethylamino)-7-(3-(5-methyl-2,5- diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H-purin-8(9H)-one (153): Compound 152 (0.100 g, 0.29 mmol), K₂CO₃ (0.060 g, 0.43 mmol), and 4-Bromobenzyl bromide (0.109 g, 0.43 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 55% ethyl acetate in hexane, to provide compound 153(82%) as white solid. Example 158 Synthesis of 2-(ethylamino)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-9- (4-(trifluoromethyl)benzyl)-7H-purin-8(9H)-one (154): Compound 152 (0.50 g, 0.15 mmol), K₂CO₃ (0.030 g, 0.22 mmol), and 4- (Trifluoromethyl)benzyl Bromide (0.044 ml, 0.22 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 55% ethyl acetate in hexane, to provide compound 154 (88%) as white solid. Example 159 Synthesis of 2-(ethylamino)-9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7- (3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H-purin-8(9H)-one (155): In a pressure tube, 10 ml of dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.005 g, 0.004 mmol) and (±)BINAP (0.006 g, 0.009 mmol) was added to the toluene one by one and purged for 5-10 minutes.2-Methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide (0.027 , 0.097 mmol) was added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu (0.037 g, 0.388 mmol). Finally compound 153 (0.05 g, 0.097 mmol) was added to the pre- stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours. Upon completion, the reaction mixture was passed through the celite bed and the filtrate was evaporated in vacuum. The residue was subjected to flash column chromatography, eluting with 45% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform to provide compound 155(90%) as brown liquid. Example 160 Synthesis of 7-cyclopentyl-9-(4-(4-(dimethylamino)piperidin-1-yl)benzyl)-2- (ethylamino)-7H-purin-8(9H)-one (156): In a pressure tube, 10 ml of dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.005 g, 0.004 mmol) and (±)BINAP (0.006 g, 0.009 mmol) was added to the toluene one by one and purged for 5-10 minutes. N,N-dimethylpiperidin-4-amine (0.011ml, 0.099 mmol) was added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu (0.037 g, 0.388 mmol). Finally compound 153 (0.05 g, 0.097 mmol) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours. Upon completion, the reaction mixture was passed through the celite bed and the filtrate was evaporated in vacuum. The residue was subjected to flash column chromatography, eluting with 45% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform to provide compound 156. Example 161 Synthesis of 2-ethoxy-4-((4-methoxybenzyl)amino)pyrimidine-5-carboxylic acid (157) : The required compound 157 was synthesized by general procedure B using Compound 14 (0.500 g, 1.70 mmol), Sodium t-butoxide (0.328 g, 3.4 mmol) and 10 mL of EtOH. The residue was purified by reverse phase column chromatography eluting with 30% acetonitrile-water to obtain pure compound 157. Example 162 Synthesis of 2-ethoxy-9-(4-methoxybenzyl)-7H-purin-8(9H)-one (158): The desired compound 158 was synthesized by general procedure D using Compound 157 (0.500g, 1.65 mmol), Diphenylphosphoryl azide (0.63 ml, 2.97 mmol), Et₃N (0.28 mL, 1.97mmol) in dry 5 mL of DMA. Completion of the reaction was monitored by TLC. Boiling water was poured into the reaction mixture. The aqueous solution was extracted with ethyl acetate and the organic layer was dried over Na₂SO₄ and evaporated under vacuum. The residue was purified by silica gel column chromatography eluting with 2% methanol in chloroform, to provide compound 158. Example 163 Synthesis of 7-(3-chloropropyl)-2-ethoxy-9-(4-methoxybenzyl)-7H-purin-8(9H)-one (159): Compound 158 (0.100 g, 0.32 mmol), K₂CO₃ (0.070 g, 0.50 mmol), and1-Bromo-3- chloropropane (0.040 mL, 0.40 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 159. Example 164 Synthesis of 2-ethoxy-9-(4-methoxybenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan- 2-yl)propyl)-7H-purin-8(9H)-one (160): Compound 159 (0.05 g, 0.13 mmol), K₂CO₃ (0.027g, 0.19 mmol), and 2-Methyl-2,5- diazabicyclo[2.2.1]heptane dihydrobromide(0.053 g, 0.19 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 160. Example 165 Synthesis of 7-cyclopentyl-2-ethoxy-9-(4-methoxybenzyl)-7H-purin-8(9H)-one (161): Compound 158 (0.05 g, 0.16 mmol), K₂CO₃ (0.035 g, 0.25 mmol), and Bromocyclopentane (0.020 mL, 0.20 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 161. Example 166 Synthesis of 7-cyclopentyl-2-ethoxy-7H-purin-8(9H)-one (162): Compound 161 (0.100 g, 0.26 mmol) was taken in a 10 ml RB. TFMSA (0.12 ml, 1.31 mmol) was added to the solid sample followed by the addition of TFA (0.02 ml, 0.26 mmol) at 0 °C. The reaction mixture was stirred for 3 hours at room temperature. After the completion of the reaction, the reaction mixture was neutralized with 4 (N) NaOH. The water part was extracted with chloroform for 3 times. The organic solvent was evaporated under vacuum and the residue was purified by flash column chromatography, with 5% methanol in chloroform, to provide compound 162. Example 167 Synthesis of 9-(4-bromobenzyl)-7-cyclopentyl-2-ethoxy-7H-purin-8(9H)-one (163): Compound 162 (0.100 g, 0.38 mmol), K₂CO₃ (0.079 g, 0.57 mmol), and 4-Bromobenzyl bromide (0.145 g, 0.59 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 55% ethyl acetate in hexane, to provide compound 163. Example 168 Synthesis of 2-ethoxy-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H- purin-8(9H)-one (164): Compound 160 (0.100 g, 0.21 mmol) was taken in a 10 ml RB. TFMSA (0.094 ml, 1.07 mmol) was added to the solid sample followed by the addition of TFA (0.016 ml, 0.21 mmol) at 0 °C. The reaction mixture was stirred for 3 hours at room temperature. After the completion of the reaction, the reaction mixture was neutralized with 4 (N) NaOH. The water part was extracted with chloroform for 3 times. The organic solvent was evaporated under vacuum and the residue was purified by flash column chromatography, with 95% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform, to provide compound 164. Example 169 Synthesis of 9-(4-bromobenzyl)-2-ethoxy-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)propyl)-7H-purin-8(9H)-one (165): Compound 164 (0.100 g, 0.29 mmol), K₂CO₃ (0.060 g, 0.43 mmol), and 4-Bromobenzyl bromide (0.109 g, 0.43 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 55% ethyl acetate in hexane, to provide compound 165. Example 170 Synthesis of 2-ethoxy-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-9-(4- (trifluoromethyl)benzyl)-7H-purin-8(9H)-one (166): Compound 164 (0.50 g, 0.15 mmol), K₂CO₃ (0.030 g, 0.22 mmol), and 4- (Trifluoromethyl)benzyl Bromide (0.044 ml, 0.22 mmol) were dissolved in 5 mL of dry DMF. The reaction mixture was stirred for 12 hours at 80 °C. The reaction was monitored by checking TLC. After the completion of the reaction, the mixture was partitioned with chloroform and ice-water. The organic layer was evaporated in reduced pressure. The residue was purified by flash column chromatography, with 55% ethyl acetate in hexane, to provide compound 166. Example 171 Synthesis of 2-ethoxy-9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7-(3-(5- methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H-purin-8(9H)-one (167): In a pressure tube, 10 ml of dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.005 g, 0.004 mmol) and (±)BINAP (0.006 g, 0.009 mmol) was added to the toluene one by one and purged for 5-10 minutes.2-Methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide (0.027 , 0.097 mmol) was added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu (0.037 g, 0.388 mmol). Finally compound 165 (0.05 g, 0.097 mmol) was added to the pre- stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours. Upon completion, the reaction mixture was passed through the celite bed and the filtrate was evaporated in vacuum. The residue was subjected to flash column chromatography, eluting with 45% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform to provide compound 167. Example 172 Synthesis of 9-(4-(4-(dimethylamino)piperidin-1-yl)benzyl)-2-ethoxy-7-(3-(5-methyl-2,5- diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H-purin-8(9H)-one (168): In a pressure tube, 10 ml of dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.005 g, 0.004 mmol) and (±)BINAP (0.006 g, 0.009 mmol) was added to the toluene one by one and purged for 5-10 minutes. N,N-dimethylpiperidin-4-amine (0.011 ml, 0.099 mmol) was added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu (0.037 g, 0.388 mmol). Finally compound 165 (0.05 g, 0.097 mmol) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours. Upon completion, the reaction mixture was passed through the celite bed and the filtrate was evaporated in vacuum. The residue was subjected to flash column chromatography, eluting with 45% CMA (85% chloroform+10% methanol+5% ammonia) in chloroform to provide compound 168. Example 173 Synthesis of ethyl 4-((4-methoxybenzyl)amino)-2-((3-(pyrrolidin-1- yl)propyl)amino)pyrimidine-5-carboxylate (169): Compound 14 (0.500 g, 1.55 mmol), Et₃N (0.32 mL, 2.33 mmol), and3-(Pyrrolidin-1- yl)propan-1-amine(0.29 mL, 2.33 mmol) were dissolved in 5 mL of dry acetonitrile. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 80 % ethyl acetate in hexane to provide compound 169 (88%) as white fluffy solid.1H NMR (400 MHz, Chloroform-d) δ 8.53 (s, 1H), 7.25 (d, J = 8.8 Hz, 3H), 6.85 (d, J = 8.8 Hz, 2H), 4.63 (s, 2H), 4.23 (q, J = 7.2 Hz, 2H), 3.78 (s, 3H), 3.53-3.45 (m, 2H), 2.58-2.47 (m, 6H), 1.82-1.74 (t, J = 5.2 Hz, 6H), 1.32 (t, J = 7.2 Hz, 3H). Example 174 Synthesis of 4-((4-methoxybenzyl)amino)-2-((3-(pyrrolidin-1- yl)propyl)amino)pyrimidine-5-carboxylic acid (170): Compound 169 (0.500 g, 1.20 mmol) in 5 ml THF was added in the pre-stirred solution of potassium hydroxide (4 equivalent) in 5 ml of water. The reaction was then performed according to general procedure C. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 170 (82%) to as brown solid.1H NMR (400 MHz, DMSO-d6) δ 10.43 (t, J = 5.6 Hz, 1H), 8.22 (s, 1H), 7.22 (d, J = 8.8 Hz, 2H), 6.85 (d, J = 8.4 Hz, 2H), 4.47 (d, J = 5.6 Hz, 2H), 3.71 (s, 3H), 3.25 (q, J = 5.6 Hz, 2H), 2.41 – 2.34 (m, 6H), 1.67 – 1.59 (m, 6H). Example 175 Synthesis of 9-(4-methoxybenzyl)-2-((3-(pyrrolidin-1-yl)propyl)amino)-7H-purin-8(9H)- one (171): Compound 170 (0.500 g, 1.30 mmol) and Diphenylphosphoryl azide (0.50 ml, 2.33 mmol) were taken in dry 5 mL of DMA and Et3N (0.27 mL, 1.94 mmol) was added to it. The reaction was then performed according to general procedure D. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography eluting with 9% methanol in chloroform, to provide compound 171(85%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.75 (s, 1H), 7.41 (d, J = 8.8 Hz, 2H), 6.81 (d, J = 8.4 Hz, 2H), 4.91 (s, 2H), 3.76 (s, 3H), 3.48-3.41 (m, 2H), 2.61 – 2.57 (m, 2H), 2.56-2.53 (m, 4H), 1.88 – 1.82 (m, 2H), 1.81-1.77 (m, 4H). Example 176 Synthesis of 7-butyl-9-(4-methoxybenzyl)-2-((3-(pyrrolidin-1-yl)propyl)amino)-7H- purin-8(9H)-one (172): Compound 171 (0.05 g, 0.13 mmol), K₂CO₃ (0.027 g, 0.19 mmol), and n-Butylbromide(0.019 mL, 0.19 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 60 % ethyl acetate in hexane to provide compound 172 (90%) as white solid. Example 177 Synthesis of 7-cyclopentyl-9-(4-methoxybenzyl)-2-((3-(pyrrolidin-1-yl)propyl)amino)- 7H-purin-8(9H)-one (173): Compound 171 (0.05 g, 0.13 mmol), K₂CO₃ (0.027 g, 0.19 mmol), andBromocyclopentane(0.021 mL, 0.19 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 60 % ethyl acetate in hexane to provide compound 173 (94%) as white solid.1H NMR (400 MHz, Chloroform-d) δ 7.77 (s, 1H), 7.43 (d, J = 8.8 Hz, 2H), 6.81 (d, J = 8.8 Hz, 2H), 5.45 (t, J = 5.2 Hz, 1H), 4.90 (s, 2H), 4.76 (quin, J = 8.8Hz, 1H), 3.74 (s, 3H), 3.45 (q, J = 6.4 Hz, 2H), 2.57 (t, J = 7.2 Hz, 2H), 2.53 – 2.50 (m, 4H), 2.03-1.95 (m, 2H), 1.88 – 1.80 (m, 6H), 1.79-1.75 (m, 4H), 1.70 – 1.63 (m, 2H). Example 178 Synthesis of 7-((5-fluoropyridin-3-yl)methyl)-9-(4-methoxybenzyl)-2-((3-(pyrrolidin-1- yl)propyl)amino)-7H-purin-8(9H)-one (174): Compound 171 (0.05 g, 0.13 mmol), K₂CO₃ (0.027 g, 0.19 mmol), and3-(Bromomethyl)-5- fluoropyridine(0.044 g, 0.19 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 173. Example 179 Synthesis of ethyl 2-((4-fluorobenzyl)amino)-4-((4-methoxybenzyl)amino)pyrimidine-5- carboxylate (175): Compound 14 (0.500 g, 1.55 mmol), Et₃N (0.32 mL, 2.33 mmol), and4- Fluorobenzylamine(0.27 mL, 2.33 mmol) were dissolved in 5 mL of dry acetonitrile. After completion of the reaction, reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 30 % ethyl acetate in hexane to provide compound 175. Example 180 Synthesis of 2-((4-fluorobenzyl)amino)-4-((4-methoxybenzyl)amino)pyrimidine-5- carboxylic acid (176): Compound 175 (0.500 g, 1.13 mmol) in 5 ml THF was added in the pre-stirred solution of potassium hydroxide (4 equivalent) in 5 ml of water. The reaction was then performed according to general procedure C. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 176. Example 181 Synthesis of 2-((4-fluorobenzyl)amino)-9-(4-methoxybenzyl)-7H-purin-8(9H)-one (177): Compound 170 (0.500 g, 1.30 mmol) and Diphenylphosphoryl azide (0.43 ml, 2.04 mmol) were taken in dry 5 mL of DMA and Et3N (0.19 mL, 1.36 mmol) was added to it. The reaction was then performed according to general procedure D. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography eluting with 2% methanol in chloroform, to provide compound 177. Example 182 Synthesis of 7-butyl-2-((4-fluorobenzyl)amino)-9-(4-methoxybenzyl)-7H-purin-8(9H)- one (178): Compound 177 (0.05 g, 0.13 mmol), K₂CO₃ (0.027 g, 0.19 mmol), and n-Butylbromide(0.019 mL, 0.19 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 178. Example 183 Synthesis of 7-cyclopentyl-2-((4-fluorobenzyl)amino)-9-(4-methoxybenzyl)-7H-purin- 8(9H)-one (179): Compound 177 (0.05 g, 0.13 mmol), K₂CO₃ (0.027 g, 0.19 mmol), andBromocyclopentane(0.021 mL, 0.19 mmol) were dissolved in 5 mL of dry DMF. The reaction was then performed according to general procedure E and reaction mass was washed with water and extracted with ethyl acetate and purified by flash column chromatography eluting with 20 % ethyl acetate in hexane to provide compound 179. Example 184 Synthesis of ethyl 4-((1-(tert-butoxycarbonyl)piperidin-4-yl)amino)-2-chloropyrimidine- 5-carboxylate (180): Compound 1 (1g, 4.52 mmol), Et3N (0.63 mL, 4.52 mmol), and tert-butyl 4-aminocyclohexane-1-carboxylate (0.76 mL, 4.52 mmol) were dissolved in 5 mL of dry acetonitrile. The reaction was then performed according to general procedure A and the residue was purified by flash column chromatography eluting with 5 % methanol in chloroform to obtain pure compound 180 (80%) as brown semisolid. Example 185 Synthesis of (181): Compound 8 (0.500 g, 1.41 mmol) was added in the pre-stirred solution of sodium t-butoxide (0.270 g, 2.81 mmol) in 10 ml of n-BuOH. The reaction was then performed according to general procedure B. The residue was purified by reverse phase column chromatography eluting with 20% acetonitrile-water to obtain pure compound 181 (77%) as brown solid. Example 186 Synthesis of 2-butoxy-9-(3-(4-ethylpiperazin-1-yl)propyl)-7H-purin-8(9H)-one(182): Compound 9 (0.500 g, 1.37 mmol) and Diphenylphosphoryl azide (0.53 mL, 2.46 mmol) were taken in dry 5 mL of DMA and Et₃N (0.23 mL, 1.64 mmol) was added to it. The reaction was then performed according to general procedure D and the residue was purified by flash column chromatography eluting with 80% CMA (85% chloroform + 10% methanol + 5% ammonia) in chloroform to obtain pure compound 182 (78%) as brown solid. Example 187 Procedure for TLR7 Agonism and Antagonism Reporter assay The TLR7 agonistic or antagonist activity of synthesized compounds was assayed using a HEK293 cell line engineered to express human TLR7 as well as a NF-κB induced SEAP. The assay was based on the principle that TLR activation with TLR agonist leads to downstream NF-κB activation which in turn induces SEAP production and secretion into culture supernatant, causing color change upon interaction with the detection media.7 × 104 cells/well were seeded in 100 mg/mL Normocin supplemented complete DMEM medium and allowed to adhere to the substrate for 5 h at 37 °C and 5% CO₂. (Figure 1) For antagonism assays, CL264 (TLR7 agonist, 5 μg/mL) was added to the cells preincubated for 1 h with indicated doses of compounds, whereas for agonism assays, cells were only treated with indicated doses of compounds. Following overnight incubation, 50 μL of culture supernatant from each well was added to 200 μL of QUANTI-Blue detection media and constantly monitored for color change. After 1–2 h of incubation, spectrophotometric reading at 655 nm wavelength was recorded. To ensure the validity of TLR7 antagonism assay, the ability of different doses of hydroxychloroquine to inhibit TLR7 activation was studied as a positive control. (Figure 2) Two-tailed paired Student’s t-test was performed using GraphPad Prism software version 5.0. HEK-Blue hTLR7 reporter cell line, Normocin, and CL264 were purchased from Invivogen, USA. Example 188 Experimental Procedure for TLR9 Agonism and Antagonism Reporter assay The TLR9 agonistic or antagonist activity of synthesized compounds was assayed using a HEK293 cell line engineered to express human TLR9 as well as a NF-κB induced SEAP. The assay was based on the principle that TLR activation with TLR agonist leads to downstream NF-κB activation which in turn induces SEAP production and secretion into culture supernatant, causing color change upon interaction with the detection media.7 × 104 cells/well were seeded in 100 mg/mL Normocin supplemented complete DMEM medium and allowed to adhere to the substrate for 5 h at 37 °C and 5% CO₂. (Figure 3) For antagonism assays, CpGB (TLR9 agonist, 5 μg/mL) was added to the cells preincubated for 1 h with indicated doses of compounds, whereas for agonism assays, cells were only treated with indicated doses of compounds. Following overnight incubation, 50 μL of culture supernatant from each well was added to 200 μL of QUANTI-Blue detection media and constantly monitored for color change. After 1–2 h of incubation, spectrophotometric reading at 655 nm wavelength was recorded. To ensure the validity of TLR9 antagonism assay, the ability of different doses of hydroxychloroquine to inhibit TLR9 activation was studied as a positive control. (Figure 4) Two-tailed paired Student’s t-test was performed using GraphPad Prism software version 5.0. HEK-Blue hTLR9 reporter cell line, Normocin, and CpGB were purchased from Invivogen, USA. Table 1: TLR7/9 agonist/antagonist profile of synthesized compounds of general Formula (I): ^a% inhibition at 30 μM. ^bNo significant inhibition at 30 μM. ^cNo significant activation at 30 μM. ^dNo significant inhibition at 10 μM. ^fNo significant inhibition at 5 μM. ^g% inhibition at 30 μM. NT: Not tested. ADVANTAGES OF THE INVENTION The synthesized new compounds with general formula (I) of the present invention have several advantages. 1. The compounds with general formula (I) can be useful in treating various disease conditions where modulation of TLR7 and TLR9 plays a role. 2. The compounds with general formula (I) can stimulate immune response via TLR7 and TLR9 activation. 3. Specific compounds with general formula (I) can result in small molecule TLR7 agonists. 4. Specific compounds with general formula (I) can result in small molecule TLR9 agonists. 5. Specific compounds with general formula (I) result in small molecule TLR7 partial agonists. 6. Specific compounds with general formula (I) can inhibit immune stimulation mediated through TLR7 and TLR9. 7. The compounds with general formula (I) result in small molecule TLR7 antagonists. 8. The compounds with general formula (I) result in small molecule TLR9 antagonists. 9. The compounds with general formula (I) can be evaluated by reporter assay using transfected TLR7 and TLR9 cells. 10. The compounds with general formula (I) can be used in a number of clinical contexts for treating conditions involving unwanted immune activity in response to a suitable TLR ligand or TLR signalling agonist where inhibition of TLR7 and/or TLR9 mediated signalling is important.

Claims

WE CLAIM 1. The present invention relates to the compound represented by following structure I or a pharmaceutically acceptable salt thereof: Structure 1 Wherein R₁ is independently selected from groups referred to as follows: R2 is independently selected from groups referred to as follows: R₃ is independently selected from groups referred to as follows: R4 is independently selected as H. 2. The compound of structure I as claimed in Structure I consisting hydrogen (H) at C-6 is selected from the group consisting of: 2-butoxy-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(3-(piperidin-1-yl)propyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(3-(4-ethylpiperazin-1-yl)propyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-hydroxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-methylbenzyl)-7,9-dihydro-8H-purin-8-one 9-(4-bromobenzyl)-2-butoxy-7H-purin-8(9H)-one 2-butoxy-9-(4-(trifluoromethyl)benzyl)-7,9-dihydro-8H-purin-8-one 9-(4-(2-aminoethoxy)benzyl)-2-butoxy-7,9-dihydro-8H-purin-8-one 9-(4-(aminomethyl)benzyl)-2-butoxy-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-(2-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)ethoxy)benzyl)-7H-purin- 8(9H)-one 2-butoxy-9-(4-(2-(pyrrolidin-1-yl)ethoxy)benzyl)-7H-purin-8(9H)-one 2-butoxy-9-(4-(2-(dimethylamino)ethoxy)benzyl)-7H-purin-8(9H)-one 2-butoxy-9-(4-(2-(piperazin-1-yl)ethoxy)benzyl)-7H-purin-8(9H)-one 2-butoxy-9-(4-(2-morpholinoethoxy)benzyl)-7H-purin-8(9H)-one 2-butoxy-9-((6-methoxypyridin-3-yl)methyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-butyl-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-(2-hydroxyethyl)-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-(3-hydroxypropyl)-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 7-(3-aminopropyl)-2-butoxy-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 7-allyl-2-butoxy-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 7-benzyl-2-butoxy-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 9-benzyl-2-butoxy-7-butyl-7,9-dihydro-8H-purin-8-one 7-allyl-9-benzyl-2-butoxy-7,9-dihydro-8H-purin-8-one 9-benzyl-2-butoxy-7-(2-hydroxyethyl)-7,9-dihydro-8H-purin-8-one 9-benzyl-2-butoxy-7-(3-hydroxypropyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-butyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 7-allyl-2-butoxy-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-(2-hydroxyethyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-(3-hydroxypropyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one (S)-2-butoxy-7-(2,3-dihydroxypropyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one (R)-2-butoxy-7-(2,3-dihydroxypropyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 7-(3-aminopropyl)-2-butoxy-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-methoxybenzyl)-7-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 7-(2-aminoethyl)-2-butoxy-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-methoxybenzyl)-7-(4-(pyrrolidin-1-ylmethyl)benzyl)-7,9-dihydro-8H-purin-8- one 2-butoxy-7-cyclopentyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-methoxybenzyl)-7-(pyrrolidin-3-yl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-isopropyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-(4-fluorobenzyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-((5-fluoropyridin-3-yl)methyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-cyclopentyl-9-((6-methoxypyridin-3-yl)methyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-((6-methoxypyridin-3-yl)methyl)-7-(pyrrolidin-3-yl)-7,9-dihydro-8H-purin-8-one 9-(4-(aminomethyl)benzyl)-2-butoxy-7-butyl-7,9-dihydro-8H-purin-8-one 9-(4-(aminomethyl)benzyl)-2-butoxy-7-cyclopentyl-7,9-dihydro-8H-purin-8-one 2-(butylamino)-9-(3-morpholinopropyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-9-((6-methoxypyridin-3-yl)methyl)-7,9-dihydro-8H-purin-8-one 9-(4-(aminomethyl)benzyl)-2-(butylamino)-7,9-dihydro-8H-purin-8-one 9-(4-(aminomethyl)benzyl)-2-(butylamino)-7-cyclopentyl-7,9-dihydro-8H-purin-8-one 9-(4-(aminomethyl)benzyl)-2-(butylamino)-7-(pyrrolidin-3-yl)-7,9-dihydro-8H-purin-8-one 7-butyl-2-(butylamino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-7-cyclopentyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-9-(4-methoxybenzyl)-7-(pyrrolidin-3-yl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-7-isopropyl-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-7-(4-fluorobenzyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-7-((5-fluoropyridin-3-yl)methyl)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin- 8-one 7-(3-aminopropyl)-2-(butylamino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 7-(2-aminoethyl)-2-(butylamino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-(butylamino)-9-(4-methoxybenzyl)-7-(4-(pyrrolidin-1-ylmethyl)benzyl)-7,9-dihydro-8H- purin-8-one 2-(butylamino)-7-(2-(dimethylamino)ethyl)-9-(4-methoxybenzyl)-7H-purin-8(9H)-one 2-(butylamino)-9-(4-methoxybenzyl)-7-(2-(methylamino)ethyl)-7H-purin-8(9H)-one 2-(butylamino)-9-(4-methoxybenzyl)-7-(3-(pyrrolidin-1-yl)propyl)-7H-purin-8(9H)-one 2-(butylamino)-9-(4-methoxybenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)propyl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(3-methoxybenzyl)-7H-purin-8(9H)-one 9-(4-bromobenzyl)-2-(butylamino)-7-cyclopentyl-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(naphthalen-1-ylmethyl)-7H-purin-8(9H)-one 9-([1,1'-biphenyl]-4-ylmethyl)-2-(butylamino)-7-cyclopentyl-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7H- purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(4-(piperazin-1-yl)benzyl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(4-(pyrrolidin-1-yl)benzyl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(4-((5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)methyl)benzyl)-7H-purin-8(9H)-one 9-(4-bromobenzyl)-2-(butylamino)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)propyl)-7H-purin-8(9H)-one 7-cyclopentyl-9-(4-methoxybenzyl)-2-(propylamino)-7H-purin-8(9H)-one 9-(4-methoxybenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-2- (propylamino)-7H-purin-8(9H)-one 9-(4-bromobenzyl)-7-cyclopentyl-2-(propylamino)-7H-purin-8(9H)-one 9-(4-bromobenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-2- (propylamino)-7H-purin-8(9H)-one 7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-2-(propylamino)-9-(4- (trifluoromethyl)benzyl)-7H-purin-8(9H)-one 9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7-(3-(5-methyl-2,5- diazabicyclo[2.2.1]heptan-2-yl)propyl)-2-(propylamino)-7H-purin-8(9H)-one 7-cyclopentyl-2-(ethylamino)-9-(4-methoxybenzyl)-7H-purin-8(9H)-one 2-(ethylamino)-9-(4-methoxybenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)propyl)-7H-purin-8(9H)-one 9-(4-bromobenzyl)-7-cyclopentyl-2-(ethylamino)-7H-purin-8(9H)-one 9-(4-bromobenzyl)-2-(ethylamino)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl)propyl)-7H-purin-8(9H)-one 2-(ethylamino)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-9-(4- (trifluoromethyl)benzyl)-7H-purin-8(9H)-one 2-(ethylamino)-9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7-(3-(5-methyl- 2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H-purin-8(9H)-one 7-cyclopentyl-9-(4-(4-(dimethylamino)piperidin-1-yl)benzyl)-2-(ethylamino)-7H-purin- 8(9H)-one 2-ethoxy-9-(4-methoxybenzyl)-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)- 7H-purin-8(9H)-one 9-(4-bromobenzyl)-7-cyclopentyl-2-ethoxy-7H-purin-8(9H)-one 9-(4-bromobenzyl)-2-ethoxy-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H- purin-8(9H)-one 2-ethoxy-7-(3-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)propyl)-9-(4- (trifluoromethyl)benzyl)-7H-purin-8(9H)-one 2-ethoxy-9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7-(3-(5-methyl-2,5- diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H-purin-8(9H)-one 9-(4-(4-(dimethylamino)piperidin-1-yl)benzyl)-2-ethoxy-7-(3-(5-methyl-2,5- diazabicyclo[2.2.1]heptan-2-yl)propyl)-7H-purin-8(9H)-one 7-butyl-9-(4-methoxybenzyl)-2-((3-(pyrrolidin-1-yl)propyl)amino)-7,9-dihydro-8H-purin-8- one 7-cyclopentyl-9-(4-methoxybenzyl)-2-((3-(pyrrolidin-1-yl)propyl)amino)-7,9-dihydro-8H- purin-8-one 7-((5-fluoropyridin-3-yl)methyl)-9-(4-methoxybenzyl)-2-((3-(pyrrolidin-1-yl)propyl)amino)- 7,9-dihydro-8H-purin-8-one 2-((4-fluorobenzyl)amino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 7-butyl-2-((4-fluorobenzyl)amino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 7-cyclopentyl-2-((4-fluorobenzyl)amino)-9-(4-methoxybenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-7-cyclopentyl-9-(piperidin-4-yl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(4-methoxybenzyl)piperidin-4-yl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(4-fluorobenzyl)piperidin-4-yl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(3-fluorobenzyl)piperidin-4-yl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(2-fluorobenzyl)piperidin-4-yl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(naphthalen-1-ylmethyl)piperidin-4-yl)-7H-purin-8(9H)- one 2-(butylamino)-7-cyclopentyl-9-(1-((6-fluoropyridin-3-yl)methyl)piperidin-4-yl)-7H-purin- 8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-((5-fluoropyridin-3-yl)methyl)piperidin-4-yl)-7H-purin- 8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(4-(trifluoromethyl)benzyl)piperidin-4-yl)-7H-purin- 8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(4-methoxyphenyl)piperidin-4-yl)-7H-purin-8(9H)-one 2-(butylamino)-7-cyclopentyl-9-(1-(4-fluorobenzoyl)piperidin-4-yl)-7H-purin-8(9H)-one 2-(4-(2-(butylamino)-7-cyclopentyl-8-oxo-7H-purin-9(8H)-yl)piperidin-1-yl)acetamide 2-(butylamino)-7-cyclopentyl-9-(1-isobutyrylpiperidin-4-yl)-7H-purin-8(9H)-one 2-amino-9-(4-methoxybenzyl)-7H-purin-8(9H)-one 2-amino-7-cyclopentyl-9-(4-methoxybenzyl)-7H-purin-8(9H)-one 2-butoxy-9-(4-morpholinobenzyl)-7H-purin-8(9H)-one 2-butoxy-9-(4-(piperazin-1-yl)benzyl)-7,9-dihydro-8H-purin-8-one 2-(4-(4-((2-butoxy-8-oxo-7H-purin-9(8H)-yl)methyl)phenyl)piperazin-1-yl)acetamide 2-butoxy-9-(4-((1-methylpiperidin-4-yl)amino)benzyl)-7H-purin-8(9H)-one 2-butoxy-9-(4-(4-methylpiperazin-1-yl)benzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-(4-isopropylpiperazin-1-yl)benzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)benzyl)-7,9-dihydro-8H-purin-8- one 2-butoxy-9-(4-(pyrrolidin-1-yl)benzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-(piperidin-1-yl)benzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-cyclohexylbenzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-(4-(1-isopropylpiperidin-4-yl)benzyl)-7,9-dihydro-8H-purin-8-one 2-butoxy-9-((6-(5-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl)pyridin-3-yl)methyl)-7H-purin- 8(9H)-one 2-butoxy-9-((6-(4-methylpiperazin-1-yl)pyridin-3-yl)methyl)-7H-purin-8(9H)-one 9-(3-(2-oxa-5-azabicyclo[2.2.1]heptan-5-yl)propyl)-2-butoxy-7H-purin-8(9H)-one 2-butoxy-9-(3-(piperazin-1-yl)propyl)-7H-purin-8(9H)-one 2-butoxy-9-(3-(2,6-dimethylmorpholino)propyl)-7H-purin-8(9H)-one 2-butoxy-9-(3-(3,5-dimethylmorpholino)propyl)-7H-purin-8(9H)-one 9-(3-(6-oxa-3-azabicyclo[3.1.1]heptan-3-yl)propyl)-2-butoxy-7H-purin-8(9H)-one 9-(3-(3-oxa-6-azabicyclo[3.1.1]heptan-6-yl)propyl)-2-butoxy-7H-purin-8(9H)-one 4-(3-(2-butoxy-8-oxo-7H-purin-9(8H)-yl)propyl)morpholin-2-one 4-(3-(2-butoxy-8-oxo-7H-purin-9(8H)-yl)propyl)morpholin-3-one 2-butoxy-9-(3-(3-methylmorpholino)propyl)-7H-purin-8(9H)-one 2-butoxy-9-(3-(2-methylmorpholino)propyl)-7H-purin-8(9H)-one 4-(3-(2-butoxy-8-oxo-7H-purin-9(8H)-yl)propyl)morpholine-2-carbonitrile 9-(3-(8-oxa-3-azabicyclo[3.2.1]octan-3-yl)propyl)-2-butoxy-7H-purin-8(9H)-one 4-(3-(2-butoxy-8-oxo-7H-purin-9(8H)-yl)propyl)-6-methylmorpholin-2-one 2-butoxy-9-(3-(2,2-dimethylmorpholino)propyl)-7H-purin-8(9H)-one 2-butoxy-9-(3-(2,5-dimethylmorpholino)propyl)-7H-purin-8(9H)-one 4-(3-(2-butoxy-8-oxo-7H-purin-9(8H)-yl)propyl)-7-oxa-4-azaspiro[2.5]octan-6-one 2-butoxy-9-(2-morpholinoethyl)-7H-purin-8(9H)-one 7-(1-(2-aminoethyl)pyrrolidin-3-yl)-2-(butylamino)-9-(4-methoxybenzyl)-7,9-dihydro-8H- purin-8-one 2-(butylamino)-9-(4-methoxybenzyl)-7-(1-(2-(methylamino)ethyl)pyrrolidin-3-yl)-7,9- dihydro-8H-purin-8-one 2-(butylamino)-7-(1-(2-(dimethylamino)ethyl)pyrrolidin-3-yl)-9-(4-methoxybenzyl)-7,9- dihydro-8H-purin-8-one 7-(1-(2-(3-aminopyrrolidin-1-yl)ethyl)pyrrolidin-3-yl)-2-(butylamino)-9-(4-methoxybenzyl)- 7,9-dihydro-8H-purin-8-one 2-(3-(2-(butylamino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7-yl)pyrrolidin-1- yl)acetamide 2-(3-(2-(butylamino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7-yl)pyrrolidin-1- yl)-N-methylacetamide 2-(3-(2-(butylamino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7-yl)pyrrolidin-1- yl)-N,N-dimethylacetamide 2-(3-(2-(dimethylamino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7-yl)pyrrolidin- 1-yl)-N,N-dimethylacetamide 2-(3-(2-((3-(1H-imidazol-1-yl)propyl)amino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H- purin-7-yl)pyrrolidin-1-yl)-N,N-dimethylacetamide 2-(3-(9-(4-methoxybenzyl)-2-((2-(4-methylpiperazin-1-yl)ethyl)amino)-8-oxo-8,9-dihydro- 7H-purin-7-yl)pyrrolidin-1-yl)-N,N-dimethylacetamide 2-(3-(9-(4-methoxybenzyl)-2-((3-(4-methylpiperazin-1-yl)propyl)amino)-8-oxo-8,9-dihydro- 7H-purin-7-yl)pyrrolidin-1-yl)-N,N-dimethylacetamide 2-(3-(2-((4-fluorobenzyl)amino)-9-(4-methoxybenzyl)-8-oxo-8,9-dihydro-7H-purin-7- yl)pyrrolidin-1-yl)-N,N-dimethylacetamide 2-(3-(9-(4-methoxybenzyl)-8-oxo-2-((4-(trifluoromethyl)phenyl)amino)-8,9-dihydro-7H- purin-7-yl)pyrrolidin-1-yl)-N,N-dimethylacetamide 2-(3-(2-((4-trifluorophenyl)amino)-9-methyl-8-oxo-8,9-dihydro-7H-purin-7-yl)pyrrolidin-1- yl)-N,N-dimethylacetamide N,N-dimethyl-2-(3-(2-((2-(4-methylpiperazin-1-yl)ethyl)amino)-8-oxo-8,9-dihydro-7H-purin- 7-yl)pyrrolidin-1-yl)acetamide 2-(3-(9-isopropyl-2-((2-(4-methylpiperazin-1-yl)ethyl)amino)-8-oxo-8,9-dihydro-7H-purin-7- yl)pyrrolidin-1-yl)-N,N-dimethylacetamide A process for preparation of compounds of formula 1 wherein the steps comprising: (i) ethyl 2,4-dichloropyrimidine-5-carboxylate (1) was taken in dry acetonitrlie and Et₃N was added to it. Requisite amine such as 3-morpholinopropan-1-amine, 3-(piperidin-1-yl)propan-1- amine, 3-(4-ethylpiperazin-1-yl)propan-1-amine, phenylmethanamine, (4- methoxyphenyl)methanamine, 4-methoxybenzyl amine, 4-aminobenzyl amine, (4- bromophenyl)methanamine, (4-(dimethylamino)phenyl)methanamine, tert-butyl 4- (aminomethyl)benzylcarbamate, (6-methoxypyridin-3-yl)methanamine, tert-butyl 4- aminocyclohexanecarboxylate was added to the reaction mixture to obtain the compound 2, 5, 8, 14, 18, 21, 24, 30, 40, 180. (ii) Sodium tert-butoxide was added portionwise to the protic solvent nBuOH. Compound 2, 5, 8, 11, 14, 18, 21, 24, 30, 40, 180 obtained in step (i) was added to the solution to obtain the compound 3, 6, 9, 15, 19, 22, 25, 31, 41, 181 respectively. (iii) Compound 3, 6, 9, 12, 15, 19, 22, 25, 31, 41, 181 obtained in step (ii), and diphenylphosphoryl azide was taken in dry DMA. Et3N was added to the solution and refluxed for 12 hours to obtain the compound 4, 7, 10, 16, 20, 23, 26, 32, 42, 183 respectively. (iv) Compound 16 obtained in step (iii) was taken in dry DCM. BBr₃ was added to the solution dropwise at 0 °C and the reaction mixture was stirred for 30 minutes at 0 °C to obtain the product 17 as white solid. (v) Compound 17 obtained in step (iv) was taken in dry THF and boc-anhydride was added to the solution at 0 °C. The reaction mixture was then stirred for 30 minutes to get the compound 27 as white solid. (vi) Compound 27 obtained in step (v) was taken in acetonitrile and Et₃N was added to it. N- (2-bromoethyl)phthalimide was added to the reaction mixture and stirred for 2 hours at room temperature to obtain the compound 28 as white solid. (vii) Compound 28 obtained in step (vi) was treated with NH₂-NH₂. H₂O in EtOH and refluxed for 3 hours to obtain the compound 29 as gummy liquid. (viii) Compound 32 obtained in step (iii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 33 as brown solid. (ix) Compound 27 obtained in step (v) was taken in dry DMF and K₂CO₃ was added to it.1- bromo-2-chloro ethane was added to the reaction mixture and stirred for 2 hours at 50 °C to obtain the compound 34 as white solid. (x) Compound 34 obtained in step (ix) was taken in dry DMF and K₂CO₃ was added to it.2- methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, pyrrolidine,dimethylamine, tert-butyl piperazine-1-carboxylate, morpholine was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 35, 36, 37, 38, 39 respectively. (x) Compound 4 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. 1- bromobutane, 2-bromoethanol, 3-bromopropanol, N-(3-bromopropyl)phthalimide, allyl bromide, benzyl bromide was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 43, 44, 45, 46, 48, 49 respectively. (xi) Compound 46 obtained in step (x) was treated with NH₂-NH₂. H₂O in EtOH and refluxed for 3 hours to obtain the compound 47 as gummy liquid. (xii) Compound 13 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it.1- bromobutane, allyl bromide, 2-bromoethanol, 3-bromopropanol was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 50, 51, 52, 53 respectively. (xiii) Compound 16 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it.1- bromobutane, allyl bromide, 2-bromoethanol, 3-bromopropanol, (4S)-4-(bromomethyl)-2,2- dimethyl-1,3-dioxolane, (4R)-4-(bromomethyl)-2,2-dimethyl-1,3-dioxolane,N-(3- bromopropyl)phthalimide, 1-bromo-3-chloro propane, N-(2-bromoethyl)phthalimide, α,α'- dibromo-p-xylene, bromocyclopentane, 2-bromopropane, 4-fluorobenzyl bromide, 3- (bromomethyl)-2-chloro-5-fluoropyridine was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 54, 55, 56, 57, 58, 60, 62, 64, 66, 68, 70, 73, 74, 75 respectively. (xiv) Compound 58 obtained in step (xiii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 59 as gummy liquid. (xv) Compound 60 obtained in step (xiii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 61 as gummy liquid. (xvi) Compound 62 obtained in step (xiii) was treated with NH2-NH2. H2O in EtOH and refluxed for 3 hours to obtain the compound 63 as gummy liquid. (xvii) Compound 64 obtained in step (xiii) was taken in dry DMF and K₂CO₃ was added to it. Morpholine was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 65. (xviii)Compound 66 obtained in step (xiii) was treated with NH₂-NH₂. H₂O in EtOH and refluxed for 3 hours to obtain the compound 67 as gummy liquid. (xix) Compound 68 obtained in step (xiii) was taken in dry DMF and K₂CO₃ was added to it. Morpholine was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 69. (xx) Compound 16 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. tert- butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 71. (xxi) Compound 71 obtained in step (xx) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 72 as gummy liquid. (xxii) Compound 42 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. bromocyclopentane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 76. (xxiii) Compound 42 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. tert-butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 77. (xxiv) Compound 77 obtained in step (xxiii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 78 as gummy liquid. (xxv) Compound 32 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it.1- bromobutane, bromocyclopentane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 79, 81 respectively. (xxvi) Compound 79 obtained in step (xxv) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 80 as gummy liquid. (xxvii) Compound 81 obtained in step (xxv) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 82 as gummy liquid. (xxviii) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. n-butylamine was added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu. Finally compound 2 obtained from step (i)was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 83 as brown solid. (xxix) Compound 14, 40, 30 obtained in step (i) was taken in dry acetonitrile and Et3N was added to it. n-butylamine was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 86, 89, 92 respectively. (xxx) A solution of KOH in water was added to a stirred solution of Compound 83,86, 89, 92 in THF (7.5 ml). The reaction mixture was stirred at 140 °C for 8 hours to obtain the compound 84, 87, 90, 93 respectively. (xxxi) Compound 84, 87, 90, 93 obtained in step (xxx), anddiphenylphosphoryl azide was taken in dry DMA. Et3N was added to the solution and refluxed for 12 hours to obtain the compound 4, 85, 88, 91, 94 respectively. (xxxii) Compound 94 obtained in step (xxxi) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 95 as brown solid. (xxxiii) Compound 94 obtained in step (xxxii) was taken in dry DMF and K₂CO₃ was added to it. bromocyclopentane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 96. (xxxiv) Compound 96 obtained in step (xxxiii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 97 as gummy liquid. (xxxv) Compound 94 obtained in step (xxxi) was taken in dry DMF and K₂CO₃ was added to it. tert-butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 98. (xxxvi) Compound 98 obtained in step (xxxv) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 99 as gummy liquid. (xxxvii) Compound 88 obtained in step (xxxi) was taken in dry DMF and K₂CO₃ was added to it. 1-bromobutane, bromocyclopentane, 2-bromopropane, 4-fluorobenzyl bromide, 3- (bromomethyl)-2-chloro-5-fluoropyridine, N-(3-bromopropyl)phthalimide, N-(2- bromoethyl)phthalimide, α,α'-dibromo-p-xylene, 1-Bromo-2-chloro ethane, 1-bromo-3-chloro propane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 100, 101, 104, 105, 106, 107, 109, 111, 113, 116 respectively. (xxxviii) Compound 88 obtained in step (xxxi) was taken in dry DMF and K₂CO₃ was added to it. tert-butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 102. (xxxix) Compound 102 obtained in step (xxxviii) was treated with 4 (N) HCl in dioxane and stirred for 2 hours at 25 °C to obtain the compound 103 as gummy liquid. (xl) Compound 107 or Compound 109 was treated with NH2-NH2. H2O in EtOH and refluxed for 3 hours to obtain the compound 108 or 110 respectively as gummy liquid. (xli) Compound 111 obtained in step (xxxvii) was taken in dry DMF and K₂CO₃ was added to it. Pyrrolidine was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 112. (xlii) Compound 113 obtained in step (xxxvii) was taken in dry DMF and K₂CO₃ was added to it. Dimethylamine and methylamine were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 114 and 115 respectively as gummy liquid. (xliii) Compound 113 obtained in step (xxxvii) was taken in dry DMF and K₂CO₃ was added to it. Dimethylamine and methylamine were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 114 and 115 respectively as gummy liquid. (xliv) Compound 113 obtained in step (xxxvii) was taken in dry DMF and K₂CO₃ was added to it. Pyrrolidine and 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 117 and 118 respectively as gummy liquid. (xlv) Compound 101 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 119 as brown solid. (xlvi) Compound119 obtained in step (XLV) was taken in dry DMF and K₂CO₃ was added to it. 3-methoxybenzyl bromide, 4-bromobenzyl bromide, 1-(bromomethyl)naphthalene, 4- bromomethylbiphenyl, α,α'-dibromo-p-xylene, was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 120, 121, 122, 123, 128respectively. (xlvii) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, tert-butyl piperazine-1-carboxylate, piperidine depending on the requirement of desired product were added to the solution with continuous N₂ purging and the followed by the addition of NaO^tBu. Finally compound 121 obtained from step (XLVI) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 124, 125, 127 respectively. (xlviii) Compound 125 obtained from step (xlvii) was taken in 2 ml of DCM. TFA was added to the solution at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 126 respectively. (xlix) Compound 128 obtained in step (xlix) was taken in dry DMF and K₂CO₃ was added to it. Pyrrolidine and 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 129 respectively as gummy liquid. (l) Compound 118 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 130. (li) Compound 130 obtained in step (l) was taken in dry DMF and K₂CO₃ was added to it. 3- methoxybenzyl bromide, 4-bromobenzyl Bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 131 respectively. (lii) Compound 14 obtained in step (i) was taken in dry acetonitrile and Et3N was added to it. n-propylamine, ethylamine, 3-(pyrrolidin-1-yl)propan-1-amine, (4- fluorophenyl)methanamine, Boc-amide were added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 132, 144, 169, 175 and 198 respectively. (liii) A solution of KOH in water was added to a stirred solution of Compound 132, 144, 169 and 175 in THF (7.5 ml). The reaction mixture was stirred at 140 °C for 8 hours to obtain the compound 133, 145, 170, 176 and 199 respectively. (liv) Compound 133, 145, 170 and 176 obtained in step (liii), and diphenylphosphoryl azide was taken in dry DMA. Et3N was added to the solution and refluxed for 12 hours to obtain the compound 134, 146, 171, 177 and 200 respectively. (lv) Compound 134 obtained in step (l) was taken in dry DMF and K₂CO₃ was added to it. bromocyclopentane, 1-bromo-3-chloro propane were added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 135 or 136 respectively. (xlvi) Compound 136 obtained in step (lv) was taken in dry DMF and K₂CO₃ was added to it. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 137. (xlvii) Compound 135 or 137 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 138 or 140. (xlviii) Compound 138 obtained in step (xlvii) was taken in dry DMF and K₂CO₃ was added to it.4-bromobenzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 139. (xlix) Compound 138 obtained in step (xlvii) was taken in dry DMF and K₂CO₃ was added to it. 4-bromobenzyl bromide, 4-(trifluromethyl)benzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 141 and 142 respectively. (lx) In a pressure tube, dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, were added to the solution with continuous N₂ purging and the followed by the addition of NaO^tBu. Finally compound 141 obtained from step (xlix) was added to the pre- stirred reaction mixture with N2 purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 143. (lxi) Compound 146 obtained in step (liv) was taken in dry DMF and K₂CO₃ was added to it. bromocyclopentane, 1-bromo-3-chloro propane were added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 147or 148 respectively. (lxii) Compound 148 obtained in step (lxi) was taken in dry DMF and K₂CO₃ was added to it. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 149. (lxiii) Compound 147or 149was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 150 or 152. (lxiv) Compound150 obtained in step (lxiii) was taken in dry DMF and K₂CO₃ was added to it. 4-bromobenzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 151. (lxv) Compound 152 obtained in step (lxiii) was taken in dry DMF and K₂CO₃ was added to it. 4-bromobenzyl bromide, 4-(trifluromethyl)benzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 153and 154 respectively. (lxvi) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, N,N-dimethylpiperidin-4-amine were added to the solution with continuous N2 purging and the followed by the addition of NaO^tBu. Finally compound 153 obtained from step (lxv) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 155 and 156 respectively. (lxvii) Compound 14 obtained in step (i) was taken in dry nBuOH and NaOEt was added to the reaction mixture and stirred for 12 hours at 80 °C to obtain the compound 157. (lxviii) Compound 157 obtained in step (lxvii), and diphenylphosphoryl azide was taken in dry DMA. Et3N was added to the solution and refluxed for 12 hours to obtain the compound 158. (lxix) Compound 158 obtained in step (lxviii) was taken in dry DMF and K₂CO₃ was added to it. Bromocyclopentane and 1-bromo-3-chloro propane were added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 159 and 161 respectively. (lxx) Compound 159 obtained in step (lxix) was taken in dry DMF and K₂CO₃ was added to it. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide were added to the reaction mixture and stirred for 12 hours at 85 °C to obtain the compound 160. (lxxi) Compound 161 or 160 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 162 or 164. (lxxii) Compound 162 or 164 obtained in step (lxxi) was taken in dry DMF and K₂CO₃ was added to it.4-bromobenzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 163 and 165 respectively. (lxxiii) Compound 164 obtained in step (lxxii) was taken in dry DMF and K₂CO₃ was added to it.4-(trifluromethyl)benzyl bromide was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 166. (lxxiv) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Tris(dibenzylideneacetone)dipalladium(0) and (±)BINAP was added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane dihydrobromide, N,N-dimethylpiperidin-4-amine were added to the solution with continuous N₂ purging and the followed by the addition of NaO^tBu. Finally compound 165 obtained from step (lxxii) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 100 °C for 12 hours to obtain the compound 167 and 168 respectively. (lxxv) Compound 171 obtained in step (liv) was taken in dry DMF and K₂CO₃ was added to it. 1-bromobutane, Bromocyclopentane, 3-(bromomethyl)-5-fluoropyridine was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 172, 173 and 174 respectively. (lxxvi) Compound 177 obtained in step (liv) was taken in dry DMF and K₂CO₃ was added to it. 1-bromobutane, Bromocyclopentane was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 178 and 179 respectively. (lxxvii) Compound 183 obtained in step (iii) was taken in dry DMF and K₂CO₃ was added to it. Bromocyclopentane was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 184. (lxxviii) Compound 184 was treated with TFA in DCM at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 185. (lxxix) Compound 185 obtained in step (lxxviii) was taken in dry DMF and K₂CO₃ was added to it. 1-(bromomethyl)-4-methoxybenzene, 1-(bromomethyl)-4-fluorobenzene, 1- (bromomethyl)-3-fluorobenzene, 1-(bromomethyl)-2-fluorobenzene, 1- (bromomethyl)naphthalene, 5-(bromomethyl)-2-fluoropyridine, 3-(bromomethyl)-5- fluoropyridine, 1-(bromomethyl)-4-(trifluoromethyl)benzene was added to the reaction mixture and stirred for 8 hours at 25 °C to obtain the compound 186, 187, 188, 189, 190, 191, 192 and 193 respectively. (lxxix) In a pressure tube, dry Toluene was taken and sonicated with continuous N2 purging for 15 minutes. Palladium acetate(0) and X-Phos were added to the toluene one by one and purged for 5-10 minutes. 1-bromo-4-fluorobenzene was added to the solution with continuous N₂ purging and the followed by the addition of K3PO4. Finally compound 185 obtained from step (lxxviii) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 194. (lxxx) Compound 185 obtained in step (lxxviii) was taken in dry DCM and Et3N was added to it. 4-fluorobenzoyl chloride, acetyl chloride, isobutyryl chloride was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 195, 196 and 197 respectively. (lxxxi) Compound 200 was treated with 4(N) HCl in dioxane at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 201. (lxxxii) Compound 201 obtained in step (lxxxi) was taken in dry DMF and K₂CO₃ was added to it. Bromocyclopentane was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 202. (lxxxiii) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Palladium acetate(0) and X-Phos were added to the toluene one by one and purged for 5-10 minutes. Morpholine, N-bocpiperazine, 1-methylpiperidin-4-amine, 1- methylpiperazine, 1-isopropylpiperazine, 2-methyl-2,5-diazabicyclo[2.2.1]heptane, pyrrolidine, piperidine was added to the solution with continuous N2 purging and the followed by the addition of K3PO4 to attain different products. Finally compound 23 obtained from step (iii) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 203, 204, 207, 208, 209, 210, 211, 212. (lxxxiv) Compound 204 was treated with 4(N) HCl in dioxane at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 205. (lxxxv) Compound 205 obtained in step (lxxxiv) was taken in dry DMF and K₂CO₃ was added to it.2-bromoacetamide was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 206. (lxxxvi) In a pressure tube, dry dioxane was taken and sonicated with continuous N₂ purging for 15 minutes. Tetrakis(triphenylphosphine)palladium(0) and cyclohexylboronic acid or (1- (tert-butoxycarbonyl)piperidin-4-yl)boronic acid , were added to the dioxane one by one and purged for 5-10 minutes for different reaction. K₃PO₄ was added and purged for another 5 minutes. Finally compound 23 obtained from step (iii) was added to the pre-stirred reaction mixture with N₂ purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 213, 214. (lxxxvii) Compound 214 obtained in step (lxxxvi) was taken in dry DMF and Et3N was added to it. Fmoc-Cl was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 215. (lxxxviii) Compound 215 was treated with 4(N) HCl in dioxane at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 216. (lxxxix) Compound 216 obtained in step (lxxxiv) was taken in dry DMF and K₂CO₃ was added to it.2-iodopropanewas added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 217. (lxxxx) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Palladium acetate(0) and X-Phos were added to the toluene one by one and purged for 5-10 minutes. 2-methyl-2,5-diazabicyclo[2.2.1]heptane, 1-methylpiperazine were added to the solution with continuous N₂ purging and the followed by the addition of K₃PO₄ to attain different products. Finally 9-((6-bromopyridin-3-yl)methyl)-2-butoxy-7,9-dihydro-8H- purin-8-one was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 218 and 219. (lxxxxi) Compound 16 obtained in step (iii) was taken in dry DMF and Et₃N was added to it. Fmoc-Cl was added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 220. (lxxxxii) Compound 220 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 3 hours at room temperature to obtain the compound 221. (lxxxxiii) Compound 221 obtained in step (lxxxxii) was taken in dry DMF and Et3N was added to it. 1-bromo-3-chloro propane and 1-bromo-2-chloro ethane were added to the reaction mixture and stirred for 2 hours at 25 °C to obtain the compound 222 and 239. (lxxxxiv) Compound 222 obtained in step (lxxxxiii) was taken in dry DMF and K₂CO₃ was added to it. 2-oxa-5-azabicyclo[2.2.1]heptane, tert-butyl piperazine-1-carboxylate, 2,6- dimethylmorpholine, 3,5-dimethylmorpholine, 6-oxa-3-azabicyclo[3.1.1]heptane, 3-oxa-6- azabicyclo[3.1.1]heptane, morpholin-2-one, morpholin-3-one, 3-methylmorpholine, 2- methylmorpholine, morpholine-2-carbonitrile, 8-oxa-3-azabicyclo[3.2.1]octane, 6- methylmorpholin-2-one, 2,2-dimethylmorpholine, 2-methylmorpholine, 7-oxa-4- azaspiro[2.5]octan-6-one was added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237 and 238. (lxxxxv) Compound 239 obtained in step (lxxxxiii) was taken in dry DMF and K₂CO₃ was added to it. Morpholine was added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 240. (lxxxxvi) Compound 107 obtained in step () was taken in dry DMF and K₂CO₃ was added to it. 2-bromoethan-1-amine, 2-bromo-N-methylethan-1-amine, 2-bromo-N,N-dimethylethan-1- amine, 1-(2-bromoethyl)pyrrolidin-3-amine, 2-bromoacetamide, 2-bromo-N-methylacetamide, 2-bromo-N,N-dimethylacetamide were added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 241, 242, 243, 244, 245, 246, 247 respectively. (lxxxxvii) Lithium hydroxide was added portionwise to the THF and H2O solution. Compound 14 obtained in step (i) was added to the solution to obtain the compound 248. (lxxxxviii) Compound 248 obtained in step (lxxxxvii), and diphenylphosphoryl azide was taken in dry DMA. Et₃N was added to the solution and refluxed for 12 hours to obtain the compound 249. (lxxxxix) Compound 249 obtained in step (lxxxxviii) was taken in dry DMF and K₂CO₃ was added to it. tert-butyl 3-bromopyrrolidine-1-carboxylate was added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 250. (lxxxxx) Compound 250 was treated with 4(N) HCl in dioxane at 0 °C. The reaction mixture was stirred for 2 hours at room temperature to obtain the compound 251. (lxxxxxi) Compound 251 was taken in dry DMF and K₂CO₃ was added to it. 2-bromo-N,N- dimethylacetamide was added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 252. (lxxxxxii) Compound 252 was taken in dry Dioxane and K₂CO₃ was added to it. Dimethylamine, 3-(1H-imidazol-1-yl)propan-1-amine,

2-(4-methylpiperazin-1-yl)ethan-1- amine, 3-(4-methylpiperazin-1-yl)propan-1-amine, (4-fluorophenyl)methanamine were added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 253, 254, 255, 256, 257 respectively. (lxxxxxiii) In a pressure tube, dry Toluene was taken and sonicated with continuous N₂ purging for 15 minutes. Palladium acetate(0) and X-Phos were added to the toluene one by one and purged for 5-10 minutes.4-(trifluoromethyl)aniline was added to the solution with continuous N₂ purging and the followed by the addition of K₃PO₄ to attain different products. Finally compound 107 was added to the pre-stirred reaction mixture with N2 purging. The reaction mixture was heated at 90 °C for 12 hours to obtain the compound 258. (lxxxxxiv) Compound 258, 255 was treated with TFMSA and TFA at 0 °C. The reaction mixture was stirred for 3 hours at room temperature to obtain the compound 259 and 261 respectively. (lxxxxxv) Compound 259 and 261 obtained in step (lxxxxxiv) was taken in dry DMF and K₂CO₃ was added to it. Methyl iodide and 2-iodopropane were added to the reaction mixture and stirred for 12 hours at 25 °C to obtain the compound 261 and 262 respectively.

3. The compounds as claimed in claim 1, wherein compounds are useful in treating various auto-immune diseases where activation of TLR7 and 9 plays a role.

4. The compounds as claimed in claim 1, without C-6 primary amino (-NH2) and replace it with a hydrogen (H).

5. The compounds as claimed in claim 1, useful in activating TLR7 or TLR9 mediated immune-stimulatory signalling comprising contacting a cell expressing a TLR7 or TLR9 with effective amount of these compounds.

6. The compounds as claimed in claim 1, wherein compounds inhibiting TLR7 and TLR9 mediated immune-stimulatory signalling comprising contacting a cell expressing a TLR7 and TLR9 with effective amount of these compounds.

7. The compounds as claimed in claim 1, wherein compounds activate an immune system response in a subject associated with suppressed immune condition due to the suppression of TLR7 and/or TLR9 activation. They can also act as antiviral or antitumor vaccine adjuvants.

8. The compounds as claimed in claim 1, wherein compounds inhibit an immune stimulatory nucleic acid associated response in a subject that can modulate autoreactive inflammation in different autoimmune diseases where aberrant TLR7 and/or TLR9 activation is implicated for such diseases.

9. The compounds as claimed in claim 1, wherein compounds act as the TLR7 or TLR9 antagonists.

10. The compounds as claimed in claim 1, wherein compounds result in small molecule TLR7 partial agonists.