RU2798107C2 - 2,6-dimethyl-n-((pyridin-4-yl)methyl)imidazo[1,2-b]pyridazin-8-amine and 2,5-dimethyl-n-[(pyridin-4-yl)methyl derivatives ]pyrazolo[1,5-a]pyrimidin-7-amine for the treatment of viral infections - Google Patents

Abstract

FIELD: pharmaceuticals.

SUBSTANCE: invention relates to a compound having formula (I) or a pharmaceutically acceptable salt thereof, where one of X and Y is C and the other is N; R₁ is selected from halogen, CN, C1-C4 alkoxy, and C1-C4 alkyl optionally substituted with 1-3 halogens; and R₂ is 3,4-dimethoxyphenyl or 1,3-dimethyl-1H-indazol-5-yl. The invention also relates to a pharmaceutical composition for inhibiting enteroviruses based on a compound of formula (I).

EFFECT: new compounds and a pharmaceutical composition based on them have been obtained, which can be used in medicine as effective medicinal products for the treatment of enterovirus infection, where enteroviruses are selected from EV, Coxsackie virus, poliomyelitis, and rhinovirus.

18 cl, 7 tbl, 9 ex

Description

The field of technology to which the invention belongs

The present invention relates in general to compounds useful in therapy, in particular in the treatment of conditions caused by certain viruses such as the common cold, encephalitis, meningitis, myocarditis, conjunctivitis, pancreatitis, as well as diabetes, cancer and neurodegenerative diseases such as Alzheimer's and amyotrophic lateral sclerosis. More preferably, the present invention relates to certain amino-substituted heteroaromatic compounds and their use in therapy.

Prior Art

Pyrazolo[1,5-a]pyrimidine is a moiety widely used in medicinal chemistry and its derivatives are known for their potential utility as analgesics, benzodiazepine receptor antagonists, angiotensin II receptor antagonists, angiogenesis inhibitors, anti-inflammatory agents, neuropeptide Y receptor antagonists, COX2 α-inhibitor, corticotropin-releasing hormone type II receptor antagonists, and CHK1 inhibitors (e.g., Mayo et al (Adv. Synth. Catal. 2003, 345, 620-624; Tellew et al (Bioorg. Med. Chem. Lett. 2010, 20 , 7259-7264); Chen et al (Bioorg. Med. Chem. Lett. 2004, 14, 3669-3673); Labroli et al (Bioorg. Med. Chem. Lett. 2011, 21, 471-474); Griffith et al (Bioorg. Med. Chem. Lett. 2011, 21, 2641-2645); Gilligan et al., (J. Med. Chem. 2009, 52, 3073-3083); He et al. (US Patent No. 6,313,124 B1 ); and Wren et al. (WO 2010/086040).

This fragment has also been described in phosphatidylinositol 4-kinase (PI4K) inhibitors.

Bianco et al (PLoS Pathogens, 2012, 8(3), 1-17) and LaMarche et al (Antimicr. Agents and Chemother. 2012, 56(10), 5149-5156) have shown that PI4Ks play an important role in hepatitis C virus (HCV) replication, and Yang et al (J. Biol. Chem. 2012, 287(11), 8547-8467) showed the same for coronavirus. McLeod et al (ACS Med. Chem. Lett. 2013, 4(7), 585-589) and van der Schaar et al (Antimicrobial Agents Chemother. derivatives inhibiting PI4K, which are strong antiviral agents against picornavirus.

Gudmundsson et al (Bioorg. Med. Chem. Lett. 2009, 19, 5689-5692) disclosed certain 3-arylpyrazolo[1,5-a]pyrimidines with potential activity against herpes viruses.

Hwang et al (Bioorg. Med. Chem. Lett. 2012, 22, 7297-7301) describe 3-arylpyrazolo[1,5-a]pyrimidines as PI4K inhibitors with anti-HCV activity.

Décor et al (Bioorg Med Chem Lett. 2013, 23, 3841-7) also showed that PI4K plays an important role in enterovirus replication. However, it also showed that PI4K inhibitors (not 3-arylpyrazolo[1,5-a]pyrimidines and not 3-arylpyrazolo[1,5-a]pyrimidine 3-(3,4-dimethoxyphenyl)-2,5- dimethyl-N-(2-morpholinoethyl)pyrazolo[1,5-a]pyrimidin-7-amine (referred to as T-00127-HEV1)) caused death in mice in in-vivo tests, which cast doubt on the safety of PI4K inhibition.

In WO 2015/110491, certain 3-arylpyrazolo[1,5-a]pyrimidines are described as PI4K inhibitors for the treatment of diseases caused by viruses.

Imidazo[1,2-b]pyridazine derivatives have been described as Mps1 kinase inhibitors (Kusakabe, J. Med. Chem. 2015, 58, 1760-1775). Similar structural fragments have also been described as being present in inhibitors of phosphatidylinositol 4-kinase (PI4K) (McLeod et al (ACS Med. Chem. Lett. 2013, 4(7), 585-589) and van der Schaar et al (Antimicrobial Agents Chemother 2013, 57(10), 4971-4981), and PI4K inhibitors have been shown to be potential antivirals (Bianco et al, PLoS Pathogens, 2012, 8(3), 1-17; LaMarche et al, Antimicr. Agents and Chemother 2012, 56(10), 5149-5156; Decor et al, Bioorg Med Chem Lett 2013, 23, 3841-7).

Autophagy is a homeostatic decomposition process in cells that is used to generate nutrients during times of stress and as a mechanism for recycling damaged organelles or microbes in the cytosol (Karanasios et al, 2016, Autophagy at the cell, tissue and organismal level (Springer)). Many pathogens interact with autophagic signaling pathways in the host and can disrupt normal autophagy. Lai et al (Viruses, 2016, 8(32), 1-13) reported that viruses disrupt the autophagy mechanism to promote viral replication and host escape, and that inhibition of PI4KIIIβ affects autophagy processes and thereby inhibits viral replication. . Sridhar et al (EMBO J. 2013,32, 324-339) described the role of PI4KIIIβ as a key factor in autophagy, and many diseases are believed to be caused by or associated with impaired or pathological autophagy, such as neurodegenerative and neuropsychiatric diseases, cancer, heart disease, inflammatory disease, and diabetes (Polajnar et al J. Cell. Mol. Med. 2014, 9(18). 1705-1711; Levine et al, Cell, 2008, 132(1), 27-42; Barlow , et al, DNA Cell Biol, 2015, 34(4), 252-260).

Cytochrome P450 3A4 (abbreviated as CYP3A4) is one of the most important cytochrome P450 enzymes and is involved in the oxidative transformation of many clinically used therapeutic agents. Therefore, CYP3A4 inhibitors can interfere with the metabolism of a number of drugs, increasing their bioavailability and thereby causing side effects due to disproportionately high drug exposure. In patients receiving several different drugs concomitantly, such drug-drug interactions must be avoided, and this is sometimes an obstacle to the use of drugs that are otherwise suitable for use.

Accordingly, there is a continuing need for new drugs that not only have the desired therapeutic activity, but also do not or slightly affect the activity of enzymes involved in drug metabolism, in particular CYP3A4.

Brief description of the invention

The first aspect of the present invention is a compound having the formula (I)

or a pharmaceutically acceptable salt thereof, wherein

one of X and Y is C and the other is N;

R₁ selected from halogen, CN, NH(CH₃), N(CH₃)₂, C1-C4 alkoxy optionally substituted with 1-3 halogens and C1-C4 alkyl optionally substituted with 1-3 halogens, CN, NH(CH₃) or N(CH₃)₂; And

R ₂ is 3,4-dimethoxyphenyl or 1,3-dimethyl-1H-indazol-5-yl.

The compound having formula (I) combines high antiviral activity with low, preferably almost negligible, CYP3A4 inhibitory activity. Accordingly, the present invention describes a drug with a significantly reduced risk of drug interactions.

Another aspect of the present invention is a compound having formula (I), or a pharmaceutically acceptable salt thereof, for use in therapy.

Another aspect of the present invention is a pharmaceutical composition containing a compound having formula (I), or a pharmaceutically acceptable salt thereof, and optionally a pharmaceutically acceptable excipient.

Another aspect of the present invention is a compound having formula (I), or a pharmaceutically acceptable salt thereof, for use in the treatment of a viral infection, for example an RNA viral infection.

Another aspect is the use of a compound having formula (I) or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for the treatment of a viral infection, for example an RNA viral infection.

Another aspect of the present invention is a compound having formula (I), or a pharmaceutically acceptable salt thereof, capable of improving impaired or modulating abnormal autophagy in a cell, for use in the treatment of the diseases mentioned herein.

Another aspect of the present invention is a compound having formula (I), or a pharmaceutically acceptable salt thereof, for use in the treatment of a disease associated with impaired or abnormal autophagy.

Another aspect of the present invention is a compound having formula (I), or a pharmaceutically acceptable salt thereof, for use in the treatment of a disease associated with impaired autophagy.

Another aspect of the present invention is a compound having formula (I), or a pharmaceutically acceptable salt thereof, for use in the treatment of a disease associated with abnormal autophagy.

Another aspect of the present invention is a compound having formula (I), or a pharmaceutically acceptable salt thereof, for use in the treatment of non-enveloped single-stranded (+) RNA virus infection.

Another aspect of the present invention is a compound having formula (I), or a pharmaceutically acceptable salt thereof, for use in the treatment of an enterovirus infection, eg a picornavirus infection.

Another aspect of the present invention is a compound having formula (I), or a pharmaceutically acceptable salt thereof, for use in the treatment of a disease selected from pancreatitis, poliomyelitis, encephalitis, meningitis, sepsis, cancer such as breast, prostate, ovarian or intestinal cancer. , paralysis, heart diseases such as myocarditis, diabetes, common cold, enteroviral vesicular stomatitis, herpangina, pleurodynia, diarrhea, mucocutaneous lesions, respiratory disease, conjunctivitis, myositis, chronic fatigue syndrome, neuropsychiatric diseases and neurodegenerative diseases, such as multiple sclerosis, Parkinson's disease, amyotrophic lateral sclerosis, Alzheimer's disease and Huntington's disease, or inflammatory conditions.

Another aspect of the present invention is a method of treating a viral infection, such as an RNA viral infection, by administering a therapeutically effective amount of a compound having formula (I), or a pharmaceutically acceptable salt thereof, to a mammal in need of such treatment.

Detailed description of the invention

Unless otherwise indicated or clearly indicated by the context, all technical and scientific terms and abbreviations used in this text have their usual meanings known to those skilled in the art. However, some of the terms used in this text are defined below.

“Pharmaceutical acceptable” means that it can be used to formulate a pharmaceutical composition that is safe, non-toxic, and neither biologically nor otherwise undesirable, and includes acceptability for both veterinary and pharmaceutical use in humans.

The term “treating” (or “treating”) a disease or disorder may mean alleviating the disease or disorder (i.e. stopping or slowing the progress of the disease or at least one of its clinical symptoms) and/or alleviating at least one physical parameter, which may not be perceived by the patient.The term may also refer to the inhibition of a disease or disorder physically (eg, stabilization of a perceived symptom), physiologically (eg, stabilization of a physical parameter), or both.

"Therapeutically effective amount" means the amount of a compound which, when administered to a patient for the treatment of a disease, is sufficient to provide treatment for the disease of interest. A "therapeutically effective amount" varies depending on the compound, the disease and its severity, as well as the age, body weight and other parameters of the patient being treated.

The term "viral infection" means an infection caused by a virus in a mammal.

The term "RNA viral infection" means a viral infection in which the virus has RNA (ribonucleic acid) as its genetic material.

The term "non-enveloped single-stranded (+) RNA virus infection" means an infection caused by a non-enveloped single-stranded (+) RNA virus.

A "non-enveloped virus" is a virus that does not have an envelope.

A “non-enveloped single-stranded (+) RNA virus” is a virus that has a single-stranded RNA as its genetic material, and this RNA can be immediately translated into a viral protein by a cell infected with the virus.

By "abnormal autophagy" is meant, for example, autophagy that favors virus replication and release.

By “impaired autophagy” is meant an abnormally functioning autophagy in a cell.

The disease associated with impaired or pathological autophagy that can be treated according to the present invention, for example, can be selected from neurodegenerative and neuropsychiatric diseases, cancer, heart disease, inflammatory diseases and diabetes, for example, from the diseases mentioned herein.

The term "mammal" means a human or any mammalian animal, such as a primate, farm animal, domestic animal or laboratory animal. Examples of such animals are monkeys, cows, sheep, goats, horses, pigs, dogs, cats, rabbits, mice, rats, and so on. Preferably, the mammal is a human. In some embodiments, however, the mammal is another animal, such as a farm animal such as a cow, sheep, goat, horse, or pig. In some other embodiments, the mammal is a pet, such as a dog, cat, or rabbit.

The term "adjuvant" means pharmaceutically acceptable chemicals, such as those known to those skilled in the pharmaceutical arts to aid drug administration. It is a substance that can be used to prepare a pharmaceutical composition, is safe, non-toxic and not biologically or otherwise undesirable, and includes excipients acceptable for veterinary use as well as for human pharmaceutical use. Examples of excipients include binders, surfactants, diluents, disintegrants, release agents, and lubricants.

Unless otherwise indicated or evident from the context, the term "halogen" means F (fluorine), Cl (chlorine), Br (bromine) or I (iodine).

Unless otherwise specified or implied by the context, the term "Cm-Cn alkyl" means a linear or branched alkyl group containing from m to n carbon atoms. For example, the term "C1-C4 alkyl" means a linear or branched alkyl group containing from 1 to 4 carbon atoms. Such C1-C4 alkyls include methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and t-butyl.

The term “Cm-Cn alkoxy group” means a moiety having the formula

,

,

where R is Cm-Cn alkyl.

The term NH(CH ₃ ) means a fragment having the formula

.

.

The term N(CH ₃ ) ₂ means a fragment having the formula

.

.

The term CN means a fragment having the formula

.

.

In a compound having formula (I), one of X and Y is C and the other is N. In some embodiments, X is C and Y is N, i. the compound is represented by the formula (Ia)

where R ₁ and R ₂ have the meanings specified in the present text.

In some embodiments, X is N and Y is C, i. the compound is represented by the formula (Ib)

where R ₁ and R ₂ have the meanings specified in the present text.

In a compound having formula (I), R₁ selected from halogen, CN, NH(CH₃), N(CH₃)₂, C1-C4 alkoxy optionally substituted with 1-3 halogens, C1-C4 alkyl optionally substituted with 1-3 halogens, CN, NH(CH₃) or N(CH₃)₂.

In some embodiments, R ₁ is selected from halogen, CN, C1-C4 alkoxy optionally substituted with 1-3 halogens, and C1-C4 alkyl optionally substituted with 1-3 halogens.

In some embodiments, when R ₁ is halogen, that halogen is selected from F, Cl, and Br. In some embodiments, the halogen is F or Cl. In some embodiments, the halogen is F.

In some embodiments, when R ₁ is an optionally substituted C1-C4 alkyl, that alkyl is more preferably C1-C3 alkyl. In some embodiments, the alkyl is methyl or ethyl. In some embodiments, the alkyl is methyl. In some embodiments, alkyl is ethyl.

In some embodiments, when R ₁ is an optionally substituted C1-C4 alkyl, that alkyl is unsubstituted. In some other embodiments, the alkyl is substituted with 1-3 halogens, CN, NH(CH ₃ ) or N(CH ₃ ) ₂ . In some embodiments, when alkyl is substituted with 1-3 halogens, these halogens are selected from F and Cl, in particular F. In some embodiments, alkyl is alkyl substituted with 1-3 halogens and/or one substituent selected from CN, NH(CH ₃ ) and N(CH ₃ ) ₂ .

In some embodiments, when R ₁ is substituted alkyl, any substituent on that alkyl is selected from halo and CN. In some other embodiments, when R ₁ is substituted alkyl, any substituent on that alkyl is selected from halo, NH(CH ₃ ) and N(CH ₃ ) ₂ . In some other embodiments, when R ₁ is substituted alkyl, any substituent on that alkyl is selected from NH(CH ₃ ) and N(CH ₃ ) ₂ . In some other embodiments, when R ₁ is substituted alkyl, any substituent on that alkyl is selected from halo, such as F and Cl, in particular F.

In some embodiments, when R ₁ is a C1-C4 alkoxy group, the alkoxy group is more preferably a C1-C3 alkoxy group. In some embodiments, the alkoxy group is a C1-C2 alkoxy group. In some embodiments, the alkoxy group is a methoxy group. In some embodiments, when R ₁ is an optionally substituted C1-C4 alkoxy group, that alkoxy group is unsubstituted. In some other embodiments, the alkoxy group is substituted with 1-3 halogens. In some embodiments, when the alkoxy group is substituted with 1-3 halogens, any such halogen is selected from F and Cl, in particular F.

In some embodiments, R ₁ is selected from halo, CN, optionally substituted C1-C4 alkoxy, and optionally substituted C1-C4 alkyl. In some of these embodiments, R ₁ is selected from halo, an optionally substituted C1-C3 alkoxy group, and an optionally substituted C1-C3 alkyl, for example, from F, Cl, CN, an optionally substituted C1-C3 alkoxy group, and an optionally substituted C1 -C3 alkyl; or from F, Cl, CN, optionally substituted methoxy, and optionally substituted methyl and ethyl; or from F and optionally substituted methyl. In some of these embodiments, any substituent on any alkyl or alkoxy group is F or Cl, in particular F. In some other of these embodiments, R ₁ is selected from halo, an unsubstituted C1-C4 alkoxy group, and an unsubstituted C1 -C4 alkyl, for example from F, Cl, CN, C1-C3 alkoxy and C1-C3 alkyl; or from F, Cl, CN, methoxy, methyl and ethyl; or from F and methyl.

In some embodiments, R ₁ is selected from halo and optionally substituted C1-C4 alkyl. In some of these embodiments, R ₁ is selected from halo and optionally substituted C1-C3 alkyl, eg F, Cl and optionally substituted C1-C3 alkyl; or from F, Cl and optionally substituted methyl or ethyl; or from F and optionally substituted methyl or ethyl; or from F and optionally substituted methyl. In some of these embodiments, any substituent on the alkyl is F or Cl, in particular F. In some other of these embodiments, R ₁ is selected from halo and unsubstituted C1-C4 alkyl, such as F, Cl and C1- C3 alkyl; or from F, Cl, methyl and ethyl; or from F, methyl and ethyl; or from F and methyl.

In some other embodiments, R ₁ is selected from halo, unsubstituted C1-C4 alkyl, and unsubstituted C1-C4 alkoxy, such as F, Cl, C1-C3 alkyl, and C1-C3 alkoxy; or from F, Cl, methyl, ethyl and methoxy; or from F, methyl, ethyl and methoxy; or from F, methyl and methoxy; or from methyl and a methoxy group.

In some embodiments, R ₁ is selected from optionally substituted C1-C4 alkyl and optionally substituted C1-C4 alkoxy. In some embodiments, R ₁ is selected from unsubstituted C1-C4 alkyl and unsubstituted C1-C4 alkoxy. In other embodiments, R ₁ is selected from optionally substituted C1-C4 alkyl and unsubstituted C1-C4 alkoxy. In other embodiments, R ₁ is selected from C1-C4 alkyl and C1-C4 alkoxy, where the alkoxy and alkyl are optionally substituted with 1-3 halogens, e.g., 1-3 halogens selected from F and Cl, in particular 1-3 F atoms. In some embodiments, R ₁ is selected from methyl, ethyl, trifluoromethyl, and methoxy.

In other embodiments, R ₁ is selected from halogen, for example, R ₁ is F or Cl, in particular F.

In some other embodiments, R ₁ is selected from F, CN, methoxy, methyl, trifluoromethyl, and ethyl; for example, from F, methyl, trifluoromethyl and ethyl.

In a compound having formula (I), R ₂ is 3,4-dimethoxyphenyl or 1,3-dimethyl-1H-indazol-5-yl, i. e. R ₂ is a fragment having the formula (II) or (III)

.

.

In some embodiments, R ₂ is 3,4-dimethoxyphenyl, i. a moiety having the formula (II) and the compound of the present invention may be represented by the formula (Ic)

where X, Y and R ₁ have the meanings specified in the present text.

In some other embodiments, R ₂ is 1,3-dimethyl-1H-indazol-5-yl, i. a fragment having the formula (III) and the compound of the present invention may be represented by the formula (Id)

where X, Y and R ₁ have the meanings specified in the present text.

In some embodiments of a compound having formula (Ic), X is C and Y is N, i.e. the compound of the present invention may be represented by the formula (Ie)

where R ₁ has the meaning specified in the present text.

In some other embodiments of a compound having formula (Ic), X is N and Y is C, i.e. the compound of the present invention may be represented by the formula (If)

where R ₁ has the meaning specified in the present text.

In some embodiments of a compound having formula (Id), X is C and Y is N, i.e. the compound of the present invention may be represented by the formula (Ig)

where R ₁ has the meaning specified in the present text.

In certain other embodiments of a compound having formula (Id), X is N and Y is C, i.e. the compound of the present invention may be represented by the formula (Ih)

where R ₁ has the meaning specified in the present text.

Unless otherwise indicated or evident from the context, any reference to a compound having formula (I) should also be understood to mean a compound represented by any of formulas (Ia), (Ib), (Ic), (Id), ( Ie), (If), (Ig) and (Ih).

In some embodiments, the compound having formula (I) is more preferably a compound having formula (Ie) or (Ih), i.e. compound having formula (I)

or a pharmaceutically acceptable salt thereof, wherein

R ₁ has the meaning specified in the present text; And

X is C, Y is N, and R ₂ is 3,4-dimethoxyphenyl; or

X is N, Y is C, and R ₂ is 1,3-dimethyl-1H-indazol-5-yl.

Compounds having formula (I) may also be converted into their pharmaceutically acceptable salts. The term “pharmaceutically acceptable salt” of a compound means a salt that is pharmaceutically acceptable as defined herein and that has the intended pharmacological activity of the parent compound. Pharmaceutically acceptable salts include acid addition salts formed with inorganic acids, eg hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid; or formed with organic acids such as acetic acid, benzenesulfonic acid, benzoic acid, camphorsulfonic acid, citric acid, ethanesulfonic acid, fumaric acid, glucoheptonic acid, gluconic acid, glutamic acid, glycolic acid, hydroxynaphthoic acid, 2-hydroxyethanesulfonic acid, lactic acid, maleic acid, malic acid, malonic acid, mandelic acid, methanesulfonic acid, muconic acid, 2-naphthalenesulfonic acid, propionic acid, salicylic acid, succinic acid, tartaric acid, p-toluenesulfonic acid, trimethylacetic acid, etc.

In the preparation of acid addition salts, those acids are preferably used which give therapeutically acceptable salts. Examples of such acids are hydrohalic acids, sulfuric acid, phosphoric acid, nitric acid, aliphatic, alicyclic, aromatic or heterocyclic carboxylic or sulfonic acid such as formic acid, acetic acid, propionic acid, succinic acid, glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, ascorbic acid, maleic acid, hydroxymaleic acid, pyruvic acid, p-hydroxybenzoic acid, embonic acid, methanesulfonic acid, ethanesulfonic acid, hydroxyethanesulfonic acid, halobenzenesulfonic acid, toluenesulfonic acid or naphthalenesulfonic acid.

When a chiral atom is present in a chemical structure, all stereoisomers resulting from the presence of the chiral atom are encompassed by that structure, unless otherwise noted. When using the Kahn-Ingold-Prelog RS system, any asymmetric atom can be represented in the (R)- or (S)-configuration, and the compound can be represented as a mixture of its stereoisomers, for example, a racemic mixture, or as only one stereoisomer, and both of these cases are included in the scope of the present invention.

The present invention includes pharmaceutical compositions comprising a compound having formula (I), or an individual isomer thereof, a racemic or non-racemic mixture of isomers, or a pharmaceutically acceptable salt thereof, together with at least one pharmaceutically acceptable excipient, for example, a carrier, and optionally , other therapeutic and/or prophylactic ingredients.

The present invention includes pharmaceutical compositions containing at least one compound having formula (I), or an individual isomer, a racemic or non-racemic mixture of isomers, or a pharmaceutically acceptable salt thereof, together with at least one pharmaceutically acceptable excipient, for example, a carrier , and optionally other therapeutic and/or prophylactic ingredients.

The pharmaceutical composition of the present invention may be for external (topical) or systemic use, for example, for enteral administration, for example, for rectal or oral administration, or for parenteral administration to a mammal (especially a human), and contains a therapeutically effective amount of a compound of the present of the invention or a pharmaceutically acceptable salt thereof as active ingredient, in combination with a pharmaceutically acceptable excipient, for example a pharmaceutically acceptable carrier. A therapeutically effective amount of the active substance is as defined above in the text and depends, for example, on the species of the mammal, body weight, age, individual condition, individual pharmacokinetic parameters, the disease being treated, and the route of administration.

For purposes of enteral, eg oral, administration, the compounds of the present invention may be administered in a wide variety of dosage formulations. Pharmaceutical compositions and dosage forms may contain the compound or compounds of the present invention, or a pharmaceutically acceptable salt(s) thereof, as the active ingredient. Pharmaceutically acceptable carriers may be solid or liquid. Solid form preparations include powders, tablets, pills, cast tablets, sachets, suppositories, and dispersible granules. The solid carrier may be one or more substances which may also serve as diluents, flavoring agents, solubilizers, lubricants, suspending agents, binders, preservatives, tablet disintegrants, or an encapsulating material. In powders, the carrier is usually a finely divided solid which is in admixture with the finely divided active ingredient. In tablets, the active ingredient is usually mixed in suitable proportions with a carrier having the necessary binding capacity and then compressed into tablets of the desired shape and size. Suitable carriers include, but are not limited to, magnesium carbonate, magnesium stearate, talc, sugar, lactose, pectin, dextrin, starch, gelatin, gum tragacanth, methylcellulose, sodium carboxymethylcellulose, low melting wax, cocoa butter, and the like. The preparation of the active substance may contain an encapsulating material as a carrier, giving a capsule in which the active substance, with or without carriers, is surrounded by a carrier and is in association with it.

Other forms suitable for oral administration include liquid preparations, including emulsions, syrups, elixirs, aqueous solutions, aqueous suspensions or solid preparations, which are intended to be converted to liquid formulations shortly before use. Emulsions can be prepared as solutions, for example in aqueous propylene glycol, or they can contain emulsifiers, such as lecithin, sorbitan monooleate or acacia gum, for example. Aqueous solutions can be prepared by dissolving the active ingredient in water and adding suitable colorants, flavors, stabilizers and thickeners. Aqueous suspensions can be prepared by dispersing the finely divided active ingredient in water with a viscous material such as natural or synthetic gums, polymers, methylcellulose, sodium carboxymethylcellulose and other well known suspending agents. Liquid preparations include solutions, suspensions and emulsions and may contain, in addition to the active ingredient, colorants, flavors, stabilizers, buffers, artificial and natural sweeteners, dispersants, thickeners, solubilizers, and the like.

Examples of compositions for rectal administration include suppositories which may contain, for example, a suitable non-irritating excipient such as cocoa butter, synthetic esters of glycerides or polyethylene glycols which are solid at room temperature but melt and/or dissolve in the rectal cavity to release the drug. .

The compounds of the present invention can also be administered parenterally, for example, by inhalation, injection or infusion, for example, intravenous, intraarterial, intraosseous, intramuscular, intracerebral, intracerebroventricular, intraarticular, intrasternal, intrathecal, intralesional, intracranial, intradermal and subcutaneous injection or infusion.

Thus, for purposes of parenteral administration, the pharmaceutical compositions of the present invention may be in the form of a sterile injectable or infusion preparation, for example in the form of an aqueous or oily suspension. Such a suspension can be prepared according to techniques known in the art using suitable dispersing or wetting agents (eg Tween 80) and suspending agents. The sterile injection or infusion preparation may also be a sterile injection or infusion solution or suspension in a non-toxic parenterally acceptable diluent or vehicle. For example, the pharmaceutical composition may be a solution in 1,3-butanediol. Other examples of suitable carriers and solvents that can be used in the compositions of the present invention include, but are not limited to, mannitol, water, Ringer's solution, and isotonic sodium chloride solution. In addition, sterile fatty oils are widely used as a solvent or suspension medium. Any brand of fatty oils can be used for this purpose, including synthetic mono- or diglycerides. Fatty acids such as oleic acid and its glyceride derivatives can be used in injectable formulations, as well as natural pharmaceutically acceptable oils such as olive oil or castor oil, especially in their polyethoxylated versions. These oily solutions or suspensions may also contain a long chain alcohol as a diluent or dispersing agent.

Solutions for parenteral use may also contain suitable stabilizers and, if necessary, buffer substances. Suitable stabilizers include antioxidants such as sodium bisulfate, sodium sulfite or ascorbic acid alone or in combination, citric acid and its salts, and sodium EDTA. Parenteral solutions may also contain preservatives such as benzalkonium chloride, methyl or propyl paraben and chlorobutanol.

For administration by inhalation or nasal administration, suitable pharmaceutical preparations are particles, aerosols, powders, mists or droplets, for example having an average size of about 10 microns in diameter or less. For example, compositions for inhalation can be formulated as solutions in saline, using benzyl alcohol or other suitable preservatives, absorption promoters to improve bioavailability, fluorocarbons, and/or other solubilizing or dispersing agents known in the art.

In some embodiments, the formulation of the present invention is a liposomal formulation. Liposomal formulations are well known in the pharmaceutical art and are described, for example, in Remington, Essentials of Pharmaceutics, Ed. Linda Felton (Pharmaceutical Press 2012), p. 456-7, and in many other publications. For example, information on the selection of suitable liposome formulas, suitable lipids, preparation methods, and the like. easily accessible to a qualified person. Examples of lipids for liposome preparations are phospholipids, sphingolipids, sterol lipids and fatty acids. Lipids suitable for liposomal formulations are available from, for example, ^Avanti® Polar Lipids, Inc.

The pharmaceutical compositions of the present invention may also be applied topically, to the skin or to mucous membranes. For topical purposes, the pharmaceutical composition may be, for example, a lotion, gel, paste, tincture, transdermal patch or gel for transmucosal delivery.

The composition can be incorporated into a suitable paste containing the active ingredients suspended or dissolved in a carrier. Carriers for external use of the compounds of the present invention include, but are not limited to, mineral oil, liquid paraffin, white petrolatum, propylene glycol, polyoxyethylene/polyoxypropylene compounds, emulsion wax, and water.

Alternatively, the pharmaceutical composition may be formulated into a suitable lotion or cream containing the active ingredient suspended or dissolved in a carrier. Suitable carriers include, but are not limited to, mineral oil, sorbitan monostearate, polysorbate 60, cetyl ester wax, cetearyl alcohol, 2-octyldodecanol, benzyl alcohol, and water.

The pharmaceutical compositions of the present invention may also be applied topically to the lower gastrointestinal tract as rectal suppositories or enema preparations.

Suitable pharmaceutical excipients, such as carriers, and methods for preparing pharmaceutical dosage forms are described in Remington's Pharmaceutical Sciences, Mack Publishing Company, which is a standard reference in the field of drug preparation.

Pharmaceutical compositions may contain from about 1% to about 95%, preferably from about 20% to about 90% of a compound having formula (I), together with at least one pharmaceutically acceptable excipient. In general, the compounds of the present invention are administered in a therapeutically effective amount by one of the conventional methods of administering drugs having similar uses. Suitable daily dosages are in the range of 1 to 1000 mg, such as 1-500 mg per day or 1-50 mg per day, depending on many factors such as the severity of the disease being treated, the age and health of the patient, the efficacy the compound used, route of administration and formulation, as well as indications for use, etc. A person skilled in the art of treating such diseases can, without undue experimentation and on the basis of the professional knowledge and information disclosed in this application, calculate the therapeutically effective amount of the compounds of the present invention in each particular case. The compounds of the present invention may be administered as pharmaceutical preparations, including preparations suitable for enteral or parenteral administration. The preferred route of administration is oral, using a convenient daily dosage regimen which can be adjusted according to the severity of the disease.

The compound of the present invention can be used to treat diseases caused by an RNA virus infection in a mammal, for example, an infection with a non-enveloped single-stranded (+) RNA virus, in particular diseases caused by picornaviruses.

The picornavirus can be, for example, parechovirus (eg Ljungan or Parecho), cardiovirus (eg EHR virus or Tayler virus), enterovirus (eg enterovirus, coxsackie virus, poliomyelitis, rhinovirus) or hepatovirus. In the case of veterinary use, picornavirus may be, for example, aphthovirus or teshovirus.

Diseases considered to be associated with or caused by or otherwise associated with viral infection, such as picornaviruses, are, for example, neurodegenerative diseases such as multiple sclerosis, Parkinson's disease, amyotrophic lateral sclerosis, Alzheimer's disease, Huntington's disease, poliomyelitis, encephalitis , meningitis, sepsis, cancer, paralysis, myocarditis, diabetes, common cold, enteroviral vesicular stomatitis, herpangina, pleurodynia, diarrhea, mucocutaneous lesion, respiratory disease, conjunctivitis, myositis, and chronic fatigue syndrome.

It is within the skill and knowledge of one skilled in the art to synthesize and identify compounds having formula (I) of the present invention, according to the methods described below in the non-limiting Examples, as well as the general methods described in the literature, for example, in PCT/EP2018 /058522 (published as WO 2018/185120 A1) and PCT/EP2015/051177 (published as WO 2015/110491 A2), the contents of which are incorporated herein by reference.

Examples

General Methods

The reactions were carried out in hermetically sealed test tubes dried in a burner flame or in glassware dried in an oven under an excess pressure of argon or nitrogen, unless otherwise indicated. Air- or moisture-sensitive liquids and solutions were transferred with a syringe. Tetrahydrofuran (THF) was distilled over the sodium/benzophenone-ketyl system. Dichloromethane (CH ₂ Cl ₂ ) was distilled over calcium hydride. All other chemicals were obtained from commercial suppliers and used without further purification, unless otherwise noted. The molecular sieves were activated at 350° C. and ground just prior to use, then dried under vacuum in a burner flame. The progress of the reactions was monitored by thin layer chromatography (TLC) using plates coated with a 0.25 mm thick silica gel layer (E. Merck). Solutions in organic solvents were evaporated on a rotary evaporator at temperatures below 50°C. Flash column chromatography was performed with silica gel 60-120, 230-400 mesh or neutral alumina. Yields are for chromatographically and spectrally pure compounds unless otherwise noted.

Devices

¹ H and ¹³ C spectra were recorded on a Bruker AVANCE III HD spectrometer with an operating frequency of 400 MHz or a Bruker AVANCE II spectrometer with an operating frequency of 300 MHz. Values of chemical shifts are given in ppm (ppm, δ scale) downfield relative to tetramethylsilane, the residual signals of the solvent in the NMR spectrum were used as references (CHCl ₃ : δ 7.26 for 1H-NMR, δ 77.16 for 13C-NMR ). LC-MS analyzes were performed on an Agilent XCT Ion Trap equipped with Chemstation and Bruker daltonics software.

Synthesis of 3-(3,4-dimethoxyphenyl)-8-iodo-2,6-dimethylimidazo[1,2-b]pyridazine

The intermediate product 3-(3,4-dimethoxyphenyl)-8-iodo-2,6-dimethylimidazo[1,2-b]pyridazine was obtained by a multi-stage synthesis according to the procedure described below:

Stage 1: 2,6-dimethylimidazo[1,2-b]pyridazine

To a stirred solution of 6-methylpyridazin-3-ylamine (50 g, 455.3 mmol) in ethanol (500 ml) was added chloroacetone (58 ml, 683 mmol) and the solution was heated at 85°C for 10 hours. After completion of the reaction, ethanol was distilled off from the reaction mixture. The resulting crude product was purified by flash column chromatography (neutral alumina) eluting the title compound 2,6-dimethylimidazo[1,2-b]pyridazine (36 g, 53.4%) with 10% ethyl acetate in hexane to give it as dark brown solid.

Stage 2: 3-bromo-2,6-dimethylimidazo[1,2-b]pyridazine

To a stirred solution of 2,6-dimethylimidazo[1,2-b]pyridazine (36 g, 244.5 mmol) in acetonitrile (360 mL) was added N-bromosuccinimide (NBS) (52.2 g, 293.4 mmol) and stirred at room temperature for 1 hour. After completion of the reaction, acetonitrile was distilled off from the reaction mixture. The resulting crude product was purified by flash column chromatography (neutral alumina), eluting the title compound with 3-bromo-2,6-dimethylimidazo[1,2-b]pyridazine (18 g, 32.5%) with 15% ethyl acetate in hexane and getting it in the form of a solid.

Step 3: 3-(3,4-dimethoxyphenyl)-2,6-dimethylimidazo[1,2-b]pyridazine

A 100 ml round bottom flask was charged with 3-bromo-2,6-dimethylimidazo[1,2-b]pyridazine (5 g, 17.6 mmol), boronic acid ester (4.4 g, 19.4 mmol), potassium carbonate (7.5 g, 54.3 mmol) and a mixture of dioxane : water (45 ml : 5 ml). The resulting solution was degassed by bubbling nitrogen for 10 minutes and then a complex of [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium (II) with dichloromethane (Pd(dppf)Cl ₂ .DCM) (1.8 g, 2.2 mmol) was added. The reaction mixture was heated at 100 ^° C. for 16 hours. After completion of the reaction, the mixture was diluted with ethyl acetate and filtered through a pad of celite. The filtrate was partitioned between ethyl acetate and water. The ethyl acetate layer was dried over sodium sulfate and evaporated under reduced pressure. The resulting crude product was purified by flash column chromatography (neutral alumina), eluting the title compound 3-(3,4-dimethoxyphenyl)-2,6-dimethylimidazo[1,2-b]pyridazine (4.2 g, 67.7%) 30% ethyl acetate in hexane to give it as an off-white solid.

Step 4: 3-(3,4-dimethoxyphenyl)-8-iodo-2,6-dimethylimidazo[1,2-b]pyridazine

A solution of 3-(3,4-dimethoxyphenyl)-2,6- ^{dimethylimidazo} [1,2-b]pyridazine (0.2 g, 0.705 mmol) in THF (5 ml). After 10 minutes, iodine (0.178 g, 0.705 mmol) dissolved in THF (3 ml) was added and the reaction mixture was stirred at room temperature for 1 hour. The reaction was then quenched with saturated NH ₄ Cl solution and extracted with ethyl acetate. The ethyl acetate layers were dried over Na ₂ SO ₄ and evaporated under reduced pressure. The resulting crude product was purified by flash column chromatography (neutral alumina), eluting the title compound 3-(3,4-dimethoxyphenyl)-8-iodo-2,6-dimethylimidazo[1,2-b]pyridazine (30 mg, 10.7 %) with 30% ethyl acetate in hexane to give it as a pale yellow solid.

Example 1

3-(3,4-dimethoxyphenyl)-2,6-dimethyl-N-((2-methylpyridin-4-yl)methyl)imidazo[1,2-b]pyridazin-8-amine

Into a stirred solution of 3-(3,4-dimethoxyphenyl)-8-iodo-2,6-dimethylimidazo[1,2-b]pyridazine (0.1 g, 0.240 mmol) and amine (0.06 g, 0.312 mmol) in toluene (2 ml) were added cesium carbonate (0.156 g, 0.48 mmol), 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP (7 mg, 0.012 mmol) and Pd(OAc) ₂ (2 mg, 0.012 mmol The reaction mixture was stirred at 105°C for 16 hours.After completion of the reaction, the mixture was diluted with 10% MeOH-CH ₂ Cl ₂ and filtered through a pad of celite.The filtrate was evaporated and the resulting solid was washed with acetonitrile to give Ex 2 (0.09 g, 91.83%) as a light brown solid.

Example 2

3-(3,4-dimethoxyphenyl)-N-((2-fluoropyridin-4-yl)methyl)-2,6-dimethylimidazo[1,2-b]pyridazin-8-amine

Into a stirred solution of 3-(3,4-dimethoxyphenyl)-8-iodo-2,6-dimethylimidazo[1,2-b]pyridazine (0.15 g, 0.360 mmol) and amine (0.093 g, 0.46 mmol) in toluene (3 ml) were added cesium carbonate (0.23 g, 0.72 mmol), 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) (11 mg, 0.018 mmol) and Pd(OAc) ₂ (4 mg, 0.018 mmol). The reaction mixture was stirred at 105°C for 16 hours. After completion of the reaction, the mixture was diluted with 10% MeOH-CH ₂ Cl ₂ and filtered through a pad of celite. The filtrate was evaporated and the resulting solid was washed with acetonitrile to give Pr. 1 (0.120 g, 80%) as light brown solid.

Synthesis of 7-chloro-3-iodo-2,5-dimethylpyrazolo[1,5-a]pyrimidine

The intermediate product 7-chloro-3-iodo-2,5-dimethylpyrazolo[1,5-a]pyrimidine was obtained by a multi-stage synthesis according to the procedure described below:

Stage 1: 2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-ol

A round bottom flask was charged with 3-amino-5-methylpyrazole (100 g, 1.02 mol), ethyl acetoacetate (161 ml, 1.23 mol), acetic acid (300 ml) and 1,4-dioxane (1000 ml). The reaction mixture was boiled for 16 hours at 105°C. After completion of the reaction, an off-white solid was obtained which was filtered off with suction. The precipitate was washed with cold hexane and dried in vacuo to give 2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-ol (85 g, 49%) as an off-white solid.

Stage 2: 7-chloro-2,5-dimethylpyrazolo[1,5-a]pyrimidine

POCl ₃ (103 ml, 1.1 mol) was added dropwise to a solution of 2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-ol (120 g, 0.73 mol) in acetonitrile (1200 ml). After the addition was completed, the reaction mixture was heated at 80° C. for 12 hours. After completion of the reaction, POCl ₃ was distilled off from the reaction mixture. The resulting crude product was diluted with water, neutralized with saturated NaHCO ₃ solution and extracted with ethyl acetate. The organic layer was dried over sodium sulfate and evaporated under reduced pressure. The resulting crude product was purified by flash column chromatography eluting with 7-chloro-2,5-dimethylpyrazolo[1,5-a]pyrimidine with 20% ethyl acetate in hexane to give it as an off-white solid (108 g, 80.8 %).

Stage 3: 7-chloro-3-iodo-2,5-dimethylpyrazolo[1,5-a]pyrimidine

N-iodosuccinimide (163.5 g, 0.726 mol) was added in portions to an ice-cold solution of 7-chloro-2,5-dimethylpyrazolo[1,5-a]pyrimidine (120 g, 0.66 mol) in acetonitrile (1200 ml) at –10°C. . The reaction mixture was stirred at the same temperature for 1 hour. After completion of the reaction, a precipitate was observed. The reaction mixture was quenched with ice water and filtered with suction. The resulting solid was washed with hexane and dried in vacuo to give 7-chloro-3-iodo-2,5-dimethylpyrazolo[1,5-a]pyrimidine as a white solid (182.8 g, 89.9%).

Synthesis of 1,3-dimethyl-5-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-1H-indazole

Boronic acid ester 1,3-dimethyl-5-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-1H-indazole was obtained by a multi-stage synthesis according to the procedure described below:

Stage 1: 5-bromo-1,3-dimethyl-1H-indazole

A stirred solution of 1-(5-bromo-2-fluorophenyl)ethanone (50 g, 230 mmol) and N-methyl-hydrazine (42.4 ml, 805 mmol) in pyridine (500 ml) was heated at 90°C for 10 hours. After completion of the reaction, pyridine was distilled off from the reaction mixture. The resulting crude product was partitioned between water and ethyl acetate. The ethyl acetate layers were dried over sodium sulfate and evaporated. The resulting crude product was purified by flash column chromatography (neutral alumina) eluting the title compound 5-bromo-1,3-dimethyl-1H-indazole (20.23 g, 41.8%) with 2% ethyl acetate in hexane to give it as light brown viscous substance.

Step 2: 1,3-dimethyl-5-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-1H-indazole

KOAc (34 g, 345 mmol) and bispinacolate-diborone (32.3 g, 127 mmol) mmol). The reaction mixture was degassed with nitrogen for 10 minutes, then Pd(PPh ₃ ) ₄ (6.6 g, 5.57 mmol) was added and heated at 95°C for 16 hours. After the addition was completed, the reaction mixture was heated at 80° C. for 12 hours. After completion of the reaction, the mixture was filtered through celite, the filtrate was evaporated. The resulting crude product was purified by flash column chromatography (neutral alumina), eluting the title compound 1,3-dimethyl-5-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl) -1H-indazole (18 g, 52.1%) with 5% ethyl acetate in hexane to give it as an off-white solid.

Example 3

3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-fluoropyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7- amine

Step 1: N-[(2-fluoropyridin-4-yl)methyl]-3-iodo-2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-amine

Into a stirred solution of 7-chloro-3-iodo-2,5-dimethylpyrazolo[1,5-a]pyrimidine (1.1 g, 3.57 mmol) and 1-(2-fluoropyridin-4-yl)methanamine (0.586 g, 4.6 mmol ) in ethanol (5.5 ml) was added diisopropylethylamine (5.5 ml, 5 volumes) and stirred at 80°C for 6 hours. After completion of the reaction, ethanol was distilled off from the reaction mixture. The resulting crude product was partitioned between water and ethyl acetate. The ethyl acetate layers were dried over sodium sulfate and evaporated under reduced pressure. The target compound was isolated by flash column chromatography eluting with 35% ethyl acetate in hexane. Evaporation gave N-[(2-fluoropyridin-4-yl)methyl]-3-iodo-2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-amine (0.9 g, 63.82%) as light yellow substance.

Stage 2: tert-butyl [(2-fluoropyridin-4-yl)methyl](3-iodo-2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-yl)carbamate

Into a stirred solution of N-[(2-fluoropyridin-4-yl)methyl]-3-iodo-2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-amine (0.5 g, 1.26 mmol) in dichloromethane (DCM ) (5 ml) was added 4-dimethylaminopyridine (DMAP) (0.153 g, 1.26 mmol) at 0°C. Then, Boc anhydride (di-tert-butyl dicarbonate) (0.33 ml, 1.51 mmol) was added dropwise at the same temperature and stirred at room temperature for 2 hours. After completion of the reaction, the mixture was washed with water. The organic layer was dried over sodium sulfate and evaporated. The resulting crude product was purified by flash column chromatography (neutral alumina), eluting the title compound tert-butyl [(2-fluoropyridin-4-yl)methyl](3-iodo-2,5-dimethylpyrazolo[1,5-a] pyrimidin-7-yl)carbamate (0.51 g, 82.2%) with 10% ethyl acetate in hexane to give it as an off-white solid.

Step 3: [3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-pyrazolo[1,5-a]pyrimidin-7-yl]-(2- fluoro-pyridin-4-ylmethyl)-carbamic acid

A 25 ml round bottom flask was charged with tert-butyl [(2-fluoropyridin-4-yl)methyl](3-iodo-2,5-dimethylpyrazolo[1,5-a]pyrimidin-7-yl)carbamate (0.45 g, 0.904 mmol), 1,3-dimethyl-5-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-1H-indazole (0.322 g, 1.17 mmol), potassium carbonate (0.311 g, 2.26 mmol) and dioxane:water (4.5 ml:0.5 ml). The resulting solution was degassed by bubbling nitrogen for 10 minutes and then the Pd(dppf)Cl ₂ .DCM complex (0.110 g, 0.135 mmol) was added. The reaction mixture was heated at 100°C for 16 hours. After completion of the reaction, the mixture was diluted with ethyl acetate and filtered through a pad of celite. The filtrate was partitioned between ethyl acetate and water. The ethyl acetate layer was dried over sodium sulfate and evaporated under reduced pressure. The resulting crude product was purified by flash column chromatography (neutral alumina), eluting the title compound tert-butyl ester [3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-pyrazolo[1 ,5-a] pyrimidin-7-yl]-(2-fluoro-pyridin-4-ylmethyl)-carbamic acid (0.2 g, 42.9%) with 30% ethyl acetate in hexane to give it as an off-white solid .

Step 4: 3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-fluoropyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidine -7-amine

In an ice-cold solution of tert-butyl ether [3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-pyrazolo[1,5-a]pyrimidin-7-yl]-(2- fluoro-pyridin-4-ylmethyl)-carbamic acid (0.2 g, 0.388 mmol) in dichloromethane (2 ml) was added dropwise with TFA (2 ml). After the addition was completed, the reaction mixture was stirred at room temperature for 6 hours. After completion of the reaction, the solvent and excess TFA were distilled off. The resulting crude product was alkalized with 1N. NaOH solution and extracted with 10% MeOH-DCM. The organic layers were dried over sodium sulfate and evaporated. The resulting crude product was purified by flash column chromatography (neutral alumina), eluting the title compound Pr. 3 (0.06 g, 37.5%) with 70% ethyl acetate in hexane to give it as an off-white solid.

Example 4

3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-methylpyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7- amine

Stage 1: 3-iodo-2,5-dimethyl-N-[(2-methylpyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7-amine

Into a stirred solution of 7-chloro-3-iodo-2,5-dimethylpyrazolo[1,5-a]pyrimidine (1.1 g, 3.57 mmol) and 1-(2-methylpyridin-4-yl)methanamine (0.586 g, 4.6 mmol ) in ethanol (5.5 ml) was added diisopropylethylamine (5.5 ml, 5 volumes) and stirred at 80°C for 6 hours. After completion of the reaction, ethanol was distilled off from the reaction mixture. The resulting crude product was partitioned between water and ethyl acetate. The ethyl acetate layers were dried over sodium sulfate and evaporated under reduced pressure. The title compound was isolated by flash column chromatography eluting with 35% ethyl acetate in hexane. Evaporation gave 3-iodo-2,5-dimethyl-N-[(2-methylpyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7-amine (0.9 g, 40.1%) as light -yellow substance.

Step 2: (3-iodo-2,5-dimethyl-pyrazolo[1,5-a]pyrimidin-7-yl)-(2-methyl-pyridin-4-ylmethyl)-carbamic acid tert-butyl ester

Into a stirred solution of 3-iodo-2,5-dimethyl-N-[(2-methylpyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7-amine (0.5 g, 1.26 mmol) in dichloromethane ( 5 ml) was added DMAP (0.153 g, 1.26 mmol) at 0°C. Then, Boc anhydride (0.33 ml, 1.51 mmol) was added dropwise at the same temperature and stirred at room temperature for 2 hours. After completion of the reaction, the mixture was washed with water. The organic layer was dried over sodium sulfate and evaporated. The resulting crude product was purified by flash column chromatography (neutral alumina), eluting the title compound tert-butyl ester (3-iodo-2,5-dimethyl-pyrazolo[1,5-a]pyrimidin-7-yl)-(2 -methyl-pyridin-4-ylmethyl)-carbamic acid (0.51 g, 82.2%) with 10% ethyl acetate in hexane to give it as an off-white solid.

Step 3: [3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-pyrazolo[1,5-a]pyrimidin-7-yl]-(2- methyl-pyridin-4-ylmethyl)-carbamic acid

A 25 ml round bottom flask was charged with (3-iodo-2,5-dimethyl-pyrazolo[1,5-a]pyrimidin-7-yl)-(2-methyl-pyridin-4-ylmethyl)-carbamic tert-butyl ester acids (0.45 g, 0.904 mmol), 1,3-dimethyl-5-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-1H-indazole (0.322 g, 1.17 mmol), potassium carbonate (0.311g, 2.26 mmol) and dioxane:water (4.5 ml : 0.5 ml). The resulting solution was degassed by bubbling nitrogen for 10 minutes and then the Pd(dppf)Cl ₂ .DCM complex (0.110 g, 0.135 mmol) was added. The reaction mixture was heated at 100°C for 16 hours. After completion of the reaction, the mixture was diluted with ethyl acetate and filtered through a pad of celite. The filtrate was partitioned between ethyl acetate and water. The ethyl acetate layer was dried over sodium sulfate and evaporated under reduced pressure. The resulting crude product was purified by flash column chromatography (neutral alumina), eluting the title compound tert-butyl ester [3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-pyrazolo[1 ,5-a] pyrimidin-7-yl]-(2-methyl-pyridin-4-ylmethyl)-carbamic acid (0.2 g, 43.4%) with 30% ethyl acetate in hexane to give it as an off-white solid .

Stage 4: 3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-methylpyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidine -7-amine

In an ice-cold solution of tert-butyl ether [3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-pyrazolo[1,5-a]pyrimidin-7-yl]-(2- methyl-pyridin-4-ylmethyl)-carbamic acid (0.2 g, 0.388 mmol) in dichloromethane (2 ml) was added dropwise trifluoroacetic acid (TFA) (2 ml). After the addition was completed, the reaction mixture was stirred at room temperature for 6 hours. After completion of the reaction, the solvent and excess TFA were distilled off. The resulting crude product was alkalized with 1N. NaOH solution and extracted with 10% MeOH-DCM. The organic layers were dried over sodium sulfate and evaporated. The resulting crude product was purified by flash column chromatography (neutral alumina), eluting the title compound Pr. 4 (0.06 g, 37.7%) with 70% ethyl acetate in hexane to give it as an off-white solid.

Examples 5-8 were synthesized following the same general procedures as described for Examples 3 and 4.

Example 5

3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-ethylpyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7- amine

Example 6

3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-methoxypyridin-4-yl)methyl] pyrazolo[1,5-a]pyrimidin-7- amine

Example 7

3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-cyanopyridin-4-yl)methyl] pyrazolo[1,5-a]pyrimidin-7- amine

Example 8

3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-trifluoromethylpyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7- amine

The analysis data of the compounds from Examples 1-8 are shown in Table 1.

Table 1

Etc. Analysis data 1 ¹ H-NMR (DMSO-d6, 300 MHz): δ 8.36 (d, 1 H), 7.95 (s, 1 H), 7.28 (d, 1 H), 7.16 (m, 3 H), 7.07 (d, 1H), 5.82 (s, 1H), 4.15 (s, 2H), 3.78 (d, 6H), 2.43 (s, 3H), 2.23 (s, 3H), LCMS : 404.3 [M+H ], HPLC purity: 99.9% 2 ¹ H-NMR (DMSO-d6, 300 MHz): δ 8.18 (d, 1 H), 8.02 (s, 1 H), 7.33 (d, 1H), 7.28 (d, 1 H), 7.16 (dd, 1 H), 7.1 (d, 1H), 7.07 (d, 1H), 5.91 (s, 1H), 4.61 (s, 2H), 3.80 (d, 6H), 2.43 (s, 3H), 2.24 (s, 3 H), LCMS : 408.5 [M+H], HPLC purity: 99.5% 3 ¹ H-NMR (CDCl ₃ , 300 MHz): δ 8.25 (d, 1 H), 7.88 (s, 1 H), 7.75 (dd, 1H), 7.42 (d, 1 H), 7.22 (d, 1 H ), 6.97 (s, 1H), 6.76 (dd, 1H), 5.68 (s, 1H), 4.70 (s, 2H), 4.03 (d, 3H), 2.61 (s, 6H), 2.47 ( s, 3 H), LCMS : 416.4 [M+H], HPLC purity: 99.7% 4 ¹ H-NMR (CDCl ₃ , 300 MHz): δ 8.52 (d, 1 H), 7.88 (s, 1 H), 7.75 (dd, 1H), 7.41 (d, 1 H), 7.21 (d, 1 H ), 7.17 (d, 1H), 6.73 (m, 1H), 5.69 (s, 1H), 4.64 (s, 2H), 4.03 (d, 3H), 2.61 (s, 9H), 2.47 ( s, 3 H), LCMS : 412.3 [M+H], HPLC purity: 99.6% 5 ¹ H-NMR (CDCl ₃ , 300 MHz): δ 8.52 (d, 1 H), 7.88 (s, 1 H), 7.75 (dd, 1H), 7.42 (d, 1 H), 7.18 (s, 1 H ), 7.14 (d, 1H), 6.69 (m, 1H), 5.71 (s, 1H), 4.63 (s, 2H), 4.03 (d, 3H), 2.85 (q, 2H), 2.61 ( s, 6 H), 2.47 (s, 3 H), 1.32 (t, 3 H), LCMS : 426.4 [M+H], HPLC purity: 99.7% 6 ¹ H-NMR (CDCl ₃ , 300 MHz): δ 8.18 (d, 1 H), 7.88 (s, 1 H), 7.75 (dd, 1H), 7.41 (d, 1 H), 6.89 (d, 1H) , 6.73 (m, 2H), 5.72 (s, 1 H), 4.60 (s, 2 H), 4.03 (d, 3 H), 3.95 (s, 3 H), 2.60 (s, 6 H), 2.48 ( s, 3 H), LCMS : 428.4 [M+H], HPLC purity: 99.5% 7 ¹ H-NMR (CDCl ₃ , 300 MHz): δ 8.59 (d, 1 H), 8.25 (s, 1 H), 7.81 (m, 2H), 7.72 (d, 1 H), 7.49 (d, 1H) , 7.41 (d, 1H), 5.68 (s, 1 H), 4.75 (d, 2 H), 4.03 (d, 3 H), 2.60 (s, 6 H), 2.48 (s, 3 H), LCMS : 441.5 [M+18], HPLC purity: 93.7% 8 ¹ H-NMR (CDCl ₃ , 300 MHz): δ 8.76 (d, 1 H), 7.88 (s, 1 H), 7.75 (m, 2H), 7.53 (d, 1 H), 7.42 (d, 1H), 6.80 (s, 1H), 5.68 (s, 1H), 4.75 (d, 2H), 4.03 (d, 3H), 2.60 (s, 6H), 2.48 (s, 3H), LCMS : 466.4 [M+18], HPLC purity: 99.35%

Example 9

Liposomal composition

50 mg 3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-fluoropyridin-4-yl)methyl] pyrazolo[1,5-a]pyrimidin- 7-amine (Example 3) and 500 mg soy lecithin were transferred to a beaker. Chloroform (about 10 ml) was added and the mixture was stirred until the components were completely dissolved. Then the solvent was removed on a rotary evaporator, obtaining a thin lipid film. Water (10 ml) was added to the resulting lipid film and left to rehydrate the film at room temperature. The composition was thoroughly mixed and sonicated until a homogeneous dispersion was formed. The composition had a pH value of 6.42.

Biological tests

In vitro analysis in mammalian cell culture

The antiviral activity of the compounds of the present invention was evaluated by their ability to prevent the virus from causing viral cytopathic effects (CPE) in mammalian cell culture. Incubation time, cell line, cell density, and virus titer varied from assay to assay, but the general procedure was as follows: Cells were grown in 96-well flat-bottomed microplates to approximately 90% confluence (20,000-90,000 cells per well) in suitable media. The virus titer was determined on cells by the standard 50% tissue culture infection dose method (TCID ₅₀ ). Briefly, cells were infected by adding 50 μl of virus suspension and diluted 10-fold with medium. The plates were incubated at 37°C with 5% CO ₂ for 3-7 days and the cells were examined daily for CPE. After detection of CPE, the plates were stained with a solution of crystal violet by Gram and the optical density was read at 540 nm. The tests used the highest dilution of the virus, which gave > 95% CPE. Substances at a final concentration of 2.5-20 μM and the virus were added to the cells and incubated for 3-7 days depending on the virus and cell line used. As controls, uninfected cells and virus-infected cells (no compound added) were included in each plate. Cells were stained with crystal violet after CPE detection on infected controls, and optical density was read at 540 nm. The inhibition potential was calculated as % compared to uninfected and infected controls.

Compounds of the present invention from Examples 1-4 were tested using the method described above. In addition, the same test was carried out with compounds that do not have a substituent at position 2 in the pyridine ring, namely: 3-(3,4-dimethoxyphenyl)-2,5-dimethyl-N-(pyridin-4-ylmethyl)pyrazolo[ 1,5-a]pyrimidine-7-amine (Compound “X”) and 3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(pyridine-4- yl) methyl]pyrazolo[1,5-a]pyrimidin-7-amine (Compound “Y”):

Tables 2 and 3 show the inhibitory potential for the tested compounds on various picornaviruses at 10 nM and 100 nM, respectively. EV6: enterovirus line 6; EV30: enterovirus line 30; EV-D68: enterovirus D68; EV71: enterovirus line 71; Cox B1: coxsackievirus B line 1; Cox B2: coxsackievirus B line 2; Cox B3: coxsackievirus B line 3; Cox B5: coxsackie virus B line 5; Polio 1: polio virus line 1.

table 2

Inhibition at 10 nM Comm. X Ex 1 Etc. 2 Comm. Y Etc. 3 Etc. 4 EV6 100 100 100 100 88 100 EV30 100 100 100 100 100 100 EV-D68 86 85 73 85 76 81 EV71 82 68 76 87 82 76 Cox B1 100 93 100 100 68 100 Cox B2 100 100 100 100 100 100 Cox B3 100 100 100 100 100 100 Cox B5 100 80 84 85 48 74 Polio 1 100 100 100 100 100 100

Table 3

Inhibition at 100 nM Comm. X Ex 1 Etc. 2 Comm. Y Etc. 3 Etc. 4 EV6 100 100 100 100 100 100 EV30 100 100 100 100 100 100 EV-D68 86 83 68 80 70 70 EV71 82 77 75 86 81 79 Cox B1 100 100 100 100 100 100 Cox B2 100 100 100 100 100 100 Cox B3 100 100 100 100 100 100 Cox B5 100 100 100 100 100 100 Polio 1 100 100 100 100 100 100

In Vitro Assay of CYP 3A4 Enzyme Inhibition in Human Liver Microsomes by Marker Substrate Method

An in vitro CYP3A4 inhibition test was performed using human liver microsomes at a concentration of 0.5 mg/mL. Ketoconazole was used as a reference inhibitor and midazolam was used as a selectable marker substrate for the CYP 3A4 enzyme. Serial dilutions of test/control samples were made in potassium phosphate buffer (50 mM, pH 7.40) to give eight concentrations obtained by a 1:4 dilution. The percentage of acetonitrile/DMSO was kept at 2.5%/0.25% in 2.5X serially diluted control/test solutions, respectively. The final concentration of acetonitrile/DMSO was 1%/0.1%, respectively. Intermediate solutions such as 10X working solution (5 mg/ml) of human liver microsomes, 10X concentration of marker substrates in buffer, 5X concentration of cofactors (5.0 mM NADP+, 25.0 mM G-6-P, 3.0 IU/ml G-6-PDH and 10.0 mM MgCl ₂ ) were prepared in potassium phosphate buffer. The final concentrations of liver microsomes in the reaction mixture were 0.5 mg/mL, 1.0 mM NADP+, 5.0 mM G-6-P, 0.6 IU/mL G-6-PDH, and 2.0 mM _MgCl2 served as cofactors. Midazolam was tested at a test concentration of 5 μM. 40 µl of 2.5X serially diluted test compound/control solutions and 10 µl of 5X liver microsome solution were added to a 96-well plate and incubated for 10 minutes at 37° C. with shaking (400 rpm) on a Thermomixer. After pre-incubation, 20 µl of potassium phosphate buffer, 10 µl of the working solution of the appropriate selective substrate, and 20 µl of the cofactor mixture were added. The test results, expressed as IC ₅₀ in μM, are shown in Table 4.

Table 4

Compound Comm. X Etc. 1 Etc. 2 Comm. Y Etc. 3 Etc. 4 IC ₅₀ µM 0.97 23.1 >25 0.28 >25 >25

Pharmacokinetic characteristics

Preparation of formulations

Weighed 10 mg of the compound and transferred to a volumetric tube. Then 500 µl of DMA (5% v/v) was added, thoroughly mixed on a vortex mixer and sonicated until the test samples were completely dissolved. Then 5 ml of PEG 200 (50% v/v) was added and thoroughly mixed on a vortex mixer. Sterile control water (SWFI) was then added in small portions and thoroughly mixed on a vortex mixer. Finally the volume was adjusted to 10 ml with SWFI (45% v/v) to give a clear solution with a final concentration of 1 mg/ml. The pH value of the composition was 6.51. The formulation was prepared shortly before administration to the animals.

Dose Administration

Healthy adult male Sprague Dawley rats aged 8-10 weeks were used for tests after a minimum of 3 days of acclimatization. Fasted animals were administered test compound in the recommended vehicle (5% DMA + 50% PEG 200 + 45% SWFI) orally at a dosage of 10 mg/kg bw and at a volumetric dosage of 10 ml/kg bw.

Under mild isoflurane anesthesia, blood samples were taken into labeled tubes containing an anticoagulant (K ₂ EDTA - 2 mg/ml blood) at certain time points after dosing. The taken blood samples were centrifuged at 4000 rpm, 4°C for 10 minutes, the plasma was separated and stored at -80°C until analysis. The results obtained are shown in Table 5. AUC = area under the curve; MRT = mean train holding time.

Table 5

Comm. Y Example 4 Example 3* Dose (mg/kg body weight) 10 10 50 C _max (mg / ml) 2.3 ± 0.3 2.5 ± 0.9 2.3 ± 0.8 T _max (hour) 1.2 ± 0.8 1.3 ± 0.6 6±2 AUC _last (h * mg / ml) 14.8 ± 2.6 25.2 ± 10.0 42.4 ± 11.7 AUC _inf (s*mg/ml) 15.5 ± 1.9 27.4 ± 10.1 129.8 ± 55.8 AUC _extra (%) 4.6 ± 5.6 8.5 ± 5.2 64.5 ± 13.5 T _1/2 (h) 3.4 ± 1.2 6.8 ± 1.5 41.5 ± 19.7 MRT _last (h) 4.4 ± 1.1 6.7 ± 0.6 11.3 ± 0.5

* Liposomal composition

Metabolic stability

Metabolic stability analysis was performed using human/rat microsomes. The final assay formulation contained 5 µM test compound and control compound (diclofenac or imipramine) prepared from stock solutions in DMSO so that the final DMSO concentration was 0.1%, 0.25 mg/mL microsomal protein and cofactors (5.0 mM G-6-P , 0.06 U/ml G-6-PDH, 2.0 mM MgCl ₂ , 1.0 mM NADP ⁺ ). Test compound/control compounds were incubated with human/rat liver microsomes with and without cofactors. The reaction mixture (100 μl) was removed after a certain period of time, and the reaction was stopped by adding stop reagent. Samples were extracted in the presence of an internal standard and analyzed using the LC-MS/MS method. The percentage of test/control compound remaining after the indicated incubation period was calculated relative to the area of the peak at time 0 minutes.

Brief methodology

4X working concentration of test compound (20 μM) / control (20 μM) were prepared in 50 mM potassium phosphate buffer (pH 7.4) using 5 mM stock solutions in DMSO.

A 10X working concentration of human/rat liver microsome solution (2.5 mg/ml) was prepared in 50 mM potassium phosphate buffer (pH 7.40) using a stock solution of human/rat liver microsomes (protein concentration 20 mg/ml). The reaction mixture in an amount of 100 µl (for each time cutoff) was incubated with the addition of 45 µl of potassium phosphate buffer, 10 µl of a diluted solution of human/rat liver microsomes (2.5 mg/ml), 25 µl of test/control compounds (20 µM) and 20 µl cofactor/buffer mixture. The reaction mixture was further incubated at 37° C. for the indicated times (with cofactors: 0, 15, 30, 60 and 120 min; without cofactors: 0 and 120 min). 100 µl of incubated samples of test compounds and control compounds at the indicated incubation times were transferred to the respective sample extraction tubes.

Protein extraction method by precipitation

Test and control samples were extracted by protein precipitation. 100 µL of the incubated sample at each time point was added to tubes containing 200 µL of ice-cold acetonitrile and 50 µL of haloperidol solution (0.5 µg/mL). Then the tubes were thoroughly mixed on a vortex mixer and centrifuged at 10,000 rpm for 10 minutes at 4°C. The clear supernatant solution (200 μl) from the samples was analyzed by LC-MS/MS. The results obtained, expressed as percentage retention after 60 minutes of incubation, are shown in Table 6.

Table 6

Compound Human microsomes Rat microsomes Comm. Y 86.2% 89.7% Example 3 96.1% 99.4% Example 4 90.0% 84.0%

Human and rat plasma protein binding

Methodology

Plasma protein binding assays were performed on a Rapid Equilibrium Dialysis (RED) assay instrument having a dialysis membrane with a molecular weight cutoff of 8000 daltons.

Each dialysis insert had two chambers. The red chamber is for the plasma and the white chamber is for the buffer. Test compounds and control compounds (warfarin and propranolol) were prepared at the required test concentrations of 10 μM in human/rat plasma (pH adjusted to 7.40) using 10 mM stock solutions in DMSO (final DMSO concentration was 0.1%). 300 μl of the plasma sample was placed in the sample chamber. 500 μl of buffer was placed in the buffer chamber. After sealing the RED-device with adhesive film, incubated at 37°C with shaking (300 rpm) for 4 hours. After incubation, a 50 μl aliquot was taken from each well (plasma side and buffer side) and diluted with an equal volume of the opposite matrix to neutralize the effect of the matrix, after which the sample was extracted.

Protein extraction method by precipitation

All samples were extracted by protein precipitation by adding 200 μl of ice-cold acetonitrile and 50 μl of internal standard (0.1 μg/ml haloperidol solution). The tubes were thoroughly mixed on a vortex mixer and centrifuged at 10,000 rpm for 4°C for 10 minutes. The clear supernatant solution (200 μl) from the samples was analyzed by LC-MS/MS. The results obtained, expressed as % plasma protein binding, are shown in Table 7.

Table 7

Compound Human plasma Rat plasma Comm. Y 97.3% 97.6% Example 3 97.8% 94.1% Example 4 98.5% 98.3%

Claims (32)

1. Compound having formula (I)

, or a pharmaceutically acceptable salt thereof, wherein one of X and Y is C and the other is N; R ₁ is selected from halogen, CN, C1-C4 alkoxy, and C1-C4 alkyl optionally substituted with 1-3 halogens; And R ₂ is 3,4-dimethoxyphenyl or 1,3-dimethyl-1H-indazol-5-yl. 2. A compound according to claim 1, or a pharmaceutically acceptable salt thereof, wherein R ₂ is 3,4-dimethoxyphenyl. 3. A compound according to claim 1, or a pharmaceutically acceptable salt thereof, wherein R ₂ is 1,3-dimethyl-1H-indazol-5-yl. 4. Connection according to any one of paragraphs. 1-3 or a pharmaceutically acceptable salt thereof, wherein R ₁ is selected from F, CN, methoxy, methyl, trifluoromethyl, and ethyl. 5. Connection according to any one of paragraphs. 1-3 or a pharmaceutically acceptable salt thereof, wherein R ₁ is selected from halogen and C1-C4 alkyl optionally substituted with 1-3 halogens. 6. A compound according to claim 5, or a pharmaceutically acceptable salt thereof, wherein R ₁ is selected from F, methyl, trifluoromethyl, and ethyl. 7. A compound according to claim 6, or a pharmaceutically acceptable salt thereof, wherein R ₁ is methyl. 8. Connection according to any one of paragraphs. 1-7 where X is N and Y is C. 9. Connection according to any one of paragraphs. 1-7 where X is C and Y is N. 10. The compound according to claim 1, selected from the following: 3-(3,4-dimethoxyphenyl)-2,6-dimethyl-N-((2-methylpyridin-4-yl)methyl)imidazo[1,2-b]pyridazin-8-amine, 3-(3,4-dimethoxyphenyl)-N-((2-fluoropyridin-4-yl)methyl)-2,6-dimethylimidazo[1,2-b]pyridazin-8-amine, 3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-fluoropyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7- amine, 3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-methylpyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7- amine, 3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-ethylpyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7- amine, 3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-methoxypyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7- amine, 3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-cyanopyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7- amine, and 3-(1,3-dimethyl-1H-indazol-5-yl)-2,5-dimethyl-N-[(2-trifluoromethylpyridin-4-yl)methyl]pyrazolo[1,5-a]pyrimidin-7- amine, or a pharmaceutically acceptable salt thereof. 11. Pharmaceutical composition for the inhibition of enteroviruses, containing an effective amount of the compound according to any one of paragraphs. 1-10 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable excipient. 12. Pharmaceutical composition according to claim 11, wherein the enteroviruses are selected from EV, Coxsackie virus, poliomyelitis, rhinovirus. 13. Connection according to any one of paragraphs. 1-10 or a pharmaceutically acceptable salt thereof for use in the treatment of enterovirus infection. 14. A compound or pharmaceutically acceptable salt thereof for use according to claim 13, wherein the enteroviruses are selected from EV, Coxsackie virus, poliomyelitis, rhinovirus. 15. The use of a compound according to any one of paragraphs. 1-10 or a pharmaceutically acceptable salt thereof in the manufacture of a medicament for the treatment of enterovirus infection. 16. Use according to claim 17, wherein the enteroviruses are selected from EV, Coxsackie virus, poliomyelitis, rhinovirus. 17. A method of treating an enterovirus infection in a mammal, which includes administering to the mammal an effective amount of a compound according to any one of paragraphs. 1-10 or a pharmaceutically acceptable salt thereof. 18. The method of claim 17 wherein the enteroviruses are selected from EV, Coxsackie virus, poliomyelitis, rhinovirus.