WO2023042914A1 - Pyrrolidine compounds as histone deacetylase inhibitors - Google Patents

Pyrrolidine compounds as histone deacetylase inhibitors Download PDF

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WO2023042914A1
WO2023042914A1 PCT/JP2022/034827 JP2022034827W WO2023042914A1 WO 2023042914 A1 WO2023042914 A1 WO 2023042914A1 JP 2022034827 W JP2022034827 W JP 2022034827W WO 2023042914 A1 WO2023042914 A1 WO 2023042914A1
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optionally substituted
alkyl
group
acoet
salt
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Shin Miyamura
Shunpei Ishikawa
Taichi TAMAI
Tsuyoshi Nagase
Kazumi Kondo
Yukiko Mori
Kuninori Tai
Yuichiro NAKAISHI
Tatsuya KAWATO
Akimasa Sato
Tetsuya Hashimoto
Shintaro Goto
Ildiko Maria Buck
Benjamin David CONS
Thomas Daniel Heightman
Patrick SCHÖPF
Emiliano TAMANINI
Alison Jo-Anne Woolford
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Otsuka Pharmaceutical Co., Ltd.
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    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D403/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00
    • C07D403/02—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00 containing two hetero rings
    • C07D403/06—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00 containing two hetero rings linked by a carbon chain containing only aliphatic carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D401/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom
    • C07D401/02—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings
    • C07D401/12—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings linked by a chain containing hetero atoms as chain links
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D401/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom
    • C07D401/14—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing three or more hetero rings
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D403/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00
    • C07D403/14—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00 containing three or more hetero rings
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D405/00—Heterocyclic compounds containing both one or more hetero rings having oxygen atoms as the only ring hetero atoms, and one or more rings having nitrogen as the only ring hetero atom
    • C07D405/14—Heterocyclic compounds containing both one or more hetero rings having oxygen atoms as the only ring hetero atoms, and one or more rings having nitrogen as the only ring hetero atom containing three or more hetero rings
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D409/00—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms
    • C07D409/02—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms containing two hetero rings
    • C07D409/12—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms containing two hetero rings linked by a chain containing hetero atoms as chain links
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D409/00—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms
    • C07D409/14—Heterocyclic compounds containing two or more hetero rings, at least one ring having sulfur atoms as the only ring hetero atoms containing three or more hetero rings
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D417/00—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and sulfur atoms as the only ring hetero atoms, not provided for by group C07D415/00
    • C07D417/14—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and sulfur atoms as the only ring hetero atoms, not provided for by group C07D415/00 containing three or more hetero rings
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D495/00—Heterocyclic compounds containing in the condensed system at least one hetero ring having sulfur atoms as the only ring hetero atoms
    • C07D495/02—Heterocyclic compounds containing in the condensed system at least one hetero ring having sulfur atoms as the only ring hetero atoms in which the condensed system contains two hetero rings
    • C07D495/04—Ortho-condensed systems

Definitions

  • the present invention is directed to novel pyrrolidine compounds or salts thereof, which are useful as an HDAC inhibitor, and medical use thereof.
  • Histone acetylation and deacetylation processes are essential for the regulation of chromatin unfolding and gene expression.
  • Histone deacetylase (HDAC) enzymes play a key role in these post-translational modifications which makes them important therapeutic targets for a number of indications.
  • the connection between these epigenetic targets and central nervous system (CNS) diseases such as neurodegeneration has been published by NPL 1.
  • the level of histone deacetylase was found to be increased in the brain of mouse models of neurodegeneration and in patients with Alzheimer’s disease.
  • HDAC2 among 18 known human histone deacetylases was found to be responsible for the reduction of histone acetylation (NPL 1).
  • HDAC2 inhibitors have a memory-enhancing effect and an action to improve memory impairment by increasing histone acetylation in the nucleus of nerve cells, thereby altering chromatin structure and altering the profile of gene expression (NPL 2, 3). These effect and action may connect to cognitive dysfunction in Alzheimer's disease (NPL 4), Parkinson's disease (NPL 5), Lewy body dementia (NPL 5), frontotemporal dementia, frontotemporal lobar dementia, and amyotrophic lateral sclerosis (NPL 6, 7).
  • HDAC inhibitors normalize gene expression by enhancing histone acetylation (NPL 8).
  • Friedreich's ataxia one of the spinocerebellar degenerations, is thought to be caused by a marked decrease in the expression level of the FXN gene, which encodes a protein called frataxin in mitochondria, in triplet repeat disease.
  • HDAC inhibitors enhanced histone acetylation and improved FXN gene expression in stem cells from Friedreich's ataxia patients and model animals (NPL 9).
  • HDAC2 knockout mice and HDAC2 inhibitors activate nerve cells in the area around the infarction of cerebral infarction model animals and increase the plasticity of the nerves, thereby reducing the infarct lesion and restoring motor function after cerebral infarction or brain damage (NPL 10).
  • Oral administration of the class I HDAC inhibitor CI-994 to spinal cord injury model animals increases histone acetylation in the brain and ameliorates motor dysfunction. It has also been reported that it suppresses neuroinflammation by reducing neutrophils and inflammatory cytokines (NPL 11).
  • HDAC1/2/6/Sp1 is elevated in temozolomide-resistant brain tumors, which are used as the first-line treatment for high-grade astrocytoma brain tumors. It has also been reported that HDAC inhibitors cause cell senescence and induce apoptosis by rotating the cell cycle of temozolomide-resistant cancer cells (NPL 12). This suggests that brain-penetrant HDAC inhibitors can be effective against brain tumors such as glioma.
  • HDAC inhibitors exhibited a remarkable analgesic effect against neuropathic pain in animals.
  • HDAC2 has been found to be involved in mechanical and thermal hyperalgesia induced by peripheral nerve injury (NPL 13).
  • Hereditary neuropathies are a group of inherited disorders affecting the peripheral nervous system.
  • the hereditary neuropathies are divided into four major subcategories: hereditary motor and sensory neuropathy, hereditary sensory neuropathy, hereditary motor neuropathy, and hereditary sensory and autonomic neuropathy.
  • the most common type is Charcot-Marie-Tooth disease, one of the hereditary motor and sensory neuropathies.
  • Histone deacetylases plays a central role in various processes that are key for neuronal survival providing a rationale for the use of small-molecule HDAC inhibitors as a therapeutic strategy for hereditary neuropathy (NPL 14).
  • HDAC2 in forebrain pyramidal neurons prevented the negative effects of antipsychotic treatment on synaptic remodeling and cognition.
  • virally mediated activation of NF- ⁇ B signaling decreased cortical synaptic plasticity via HDAC2.
  • HDAC2 is elevated in cancers such as gastric cancer, prostate cancer, colorectal cancer, Hodgkin lymphoma, and cutaneous T cell lymphoma.
  • HDAC2 knockdown induces growth arrest, decreased viability, and increased apoptosis in colon and breast cancer cells and induced apoptosis and decreased lung cancer in animals (NPL 18). It was also reported that the rational design of selective HDAC2 inhibitors is beneficial for the therapeutic treatment of liver cancer (NPL 19).
  • HDAC pan-inhibitors have been approved by the FDA to date in cancer therapy: vorinostat, romidepsin, panobinostat and belinostat. Almost all of them share the same hydroxamate zinc binding group and their use may lead to side effects such as thrombocytopenia, neutropenia, diarrhea, nausea, vomiting and fatigue (NPL 20). This makes them unsuitable for the chronic dosing required to treat neurodegenerative disease.
  • Other examples of clinical HDACi feature the ⁇ -aminobenzamide zinc binding group which are also associated with potential toxicity issues (NPL 21).
  • NPL 1 Graeff, J. et al., Nature 2012, 483, 222-226.
  • NPL 2 Graeff, J. et al., The potential of HDAC inhibitors as cognitive enhancers. Annual review of pharmacology and toxicology, Vol 53, 2013. Volume 53, Edited by Fin PA; 2013: 311-330
  • NPL 3 Guan, S-J. et al., HDAC2 negatively regulates memory formation and synaptic plasticity. Nature. 2009, 459, 55-60.
  • NPL 4 Sung, Y-M. et al., Mercaptoacetamide-based class II HDAC inhibitor lowers Abeta levels and improves learning and memory in a mouse model of Alzheimer's disease.
  • NPL 8 Fede, E. D. et al., Exogenous and endogenous HDAC inhibitor effects in Rubinstein-Taybi syndrome models. bioRxiv April 01 2020.
  • NPL 9 Gottesfeld, J. M. et al., Increasing frataxin gene expression with histone deacetylase inhibitors as a therapeutic approach for friedreich's ataxia. J Neurochem. 2013 August; 126(0 1): 147-154.
  • NPL 10 Tang, Y. et al., Inhibiting histone deacetylase 2 (HDAC2) promotes functional recovery from stroke. J Am Heart Assoc. 2017 Oct 5; 6(10).
  • NPL 11 Zhang, S.
  • HDAC histone deacetylase
  • HDAC6 inhibitors Translating genetic and molecular insights into a therapy for axonal CMT. Brain Research (2020), 1733, 146692.
  • NPL 15 Ibi, D. et al., Antipsychotic-induced Hdac2 transcription via NF-kB leads to synaptic and cognitive side effects. Nature Neuroscience (2017), 20(9), 1247-1259.
  • NPL 16 Logan, R. W. et al., Valproate reverses mania-like behaviors in mice via preferential targeting of HDAC2. Molecular Psychiatry, 2020 Nov 24.
  • NPL 17 Shetty, M. G.
  • Histone deacetylase 2 selective inhibitors A versatile therapeutic strategy as next generation drug target in cancer therapy.
  • NPL 20 Gryder, B. E.
  • One of the problems to be solved by the present invention is to provide a novel drug for treatment or prevention of diseases involving HDACs.
  • the present inventors have achieved success in preparation of novel pyrrolidine compounds of the following Formula [I], or salts thereof, having an HDAC inhibitory activity and with good brain penetration, and found out that these compounds may be a new and promising drug for treatment and/or prevention of diseases involving HDACs. On the basis of these findings, the present invention has been accomplished.
  • One aspect of the present invention is a compound of Formula [I]: or a salt thereof (wherein a compound of Formula [I] or a salt thereof is also referred to as "Compound [I]" hereinafter), wherein R 1 is 1) an optionally substituted 6- to 10-membered aryl, 2) an optionally substituted 5- to 10-membered heteroaryl, provided that when the heteroaryl is a tetrazolyl, the tetrazolyl should bind to the pyrrolidine ring via its carbon atom, or 3) -O-C 4-10 alkyl; a ring structure A of the following formula: is any one of the following formulae (A1) to (A3): wherein ring groups G 1 and G 2 of the following formulae: are each independently 6- to 10-membered aryl or 5- to 10-membered heteroaryl, which is optionally substituted with oxo; X 1 is N, CH, or C; the following structure: in the formula (A1) is a bond, wherein
  • Compound [I] has a pyrrolidine structure with an ⁇ -carbonyl group, which could bind to a zinc binding site at an enzyme activity center via this structure, resulting in an HDAC inhibition activity.
  • Compound [I] may be a novel and potent HDAC inhibitor with good brain penetration, and could be developed as a drug for treatment and/or prevention of diseases involving HDACs with less side effects than known HDAC inhibitors such as those having hydroxamic-acid or benzamide motifs (PTL 1, PTL 2).
  • Fig. 1 shows a graph of Histon H4K12 acetylation levels in SKNSH cells treated with increasing concentrations of EX 11.
  • Fig. 2 shows a graph of Histon H3K9 acetylation levels in SKNSH cells treated with increasing concentrations of EX 11.
  • Fig. 3 shows a graph of Histon H4K12 acetylation levels in mouse brain at different time points after PO dosing of EX 11 at 100 mg/kg.
  • halogen used herein includes fluorine, chlorine, bromine, and iodine atoms, preferably fluorine and chlorine atoms.
  • alkyl refers to a straight or branched chain alkyl group having, e.g., 1 to 10 carbon atoms, i.e., C 1-10 alkyl.
  • alkyl include C 1-6 alkyl and C 4-10 alkyl, and specifically, include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl, isohexyl, 3-methylpentyl, 2-ethylbutyl, heptyl, octyl, nonyl, and decyl.
  • haloalkyl refers to a straight or branched chain alkyl group substituted with the same or different 1 to 12 halogen atoms.
  • haloalkyl include halo-C 1-6 alkyl, and specifically, include monofluoromethyl, difluoromethyl, trifluoromethyl, 2-chloroethyl, 2-bromoethyl, 2,2-difluoroethyl, 2-chloro-2-fluoroethyl, 2,2,2-trifluoroethyl, 2,2,2-trifluoro-1-methylethyl, pentafluoroethyl, 2-trifluoromethylpropyl, and 4-fluorobutyl.
  • alkenyl refers to a straight or branched chain alkenyl group having, e.g., 2 to 6 carbon atoms and 1 to 3 double bonds, i.e., C 2-6 alkenyl, and specifically, includes vinyl (i.e., ethenyl), 1-propenyl, 2-propenyl, isopropenyl, 2-methyl-1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 3-methyl-2-butenyl, 1,3-butadienyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 4-methyl-3-pentenyl, 1-hexenyl, 3-hexenyl, and 5-hexenyl.
  • alkynyl refers to a straight or branched chain alkynyl group having, e.g., 2 to 6 carbon atoms and 1 to 3 triple bonds, i.e., C 2-6 alkynyl, and specifically, includes ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-methyl-2-propynyl, 1-ethylethynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 1-hexynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, 5-hexynyl, 3,4-dimethylbutynyl, and 4-methyl-2-pentynyl.
  • cycloalkyl refers to a cyclic alkyl group having, e.g., 3 to 6 carbon atoms, i.e., C 3-6 cycloalkyl, and specifically, includes cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.
  • aryl used herein includes 6- to 10-membered aryl.
  • the term "6- to 10-membered aryl” used herein refers to a mono- or bi-cyclic aromatic hydrocarbon group having 6 to 10 carbon atoms, i.e., C 6-10 aryl, and specifically, includes phenyl and naphthyl.
  • C 6-10 aryl is optionally substituted with an oxo group, so that the C 6-10 aryl may lose the aromaticity to form a corresponding oxo-substituted carbocyclyl group.
  • aralkyl used herein refers to an arylalkyl group wherein the aryl and alkyl are defined as above.
  • heteroaryl used herein includes 5- to 10-membered heteroaryl.
  • the term “5- to 10-membered heteroaryl” used herein refers to a mono- or bi-cyclic aromatic heterocyclyl group having 5 to 10 atoms comprising at least one heteroatom, e.g., 1 to 3 heteroatoms, independently selected from the group consisting of oxygen, nitrogen, and sulfur atoms, and specifically, includes furyl, pyrrolyl, thiophenyl, thiazolyl, pyrazolyl, imidazolyl, pyridyl, pyrazinyl, benzothiophenyl, thienopyridyl, thienopyrimidinyl, furopyridyl, quinolinyl, and isoquinolinyl.
  • a 5- to 10-membered heteroaryl group is optionally substituted with an oxo group, so that the heteroaryl group may lose the aromaticity to form a corresponding oxo-sub
  • heterocyclyl used herein includes 5- to 10-membered heterocyclyl.
  • the term “5- to 10-membered heterocyclyl” used herein refers to a mono- or bi-cyclic saturated or partially unsaturated heterocyclyl group having 5 to 10 atoms comprising at least one heteroatom, e.g., 1 to 3 heteroatoms, independently selected from the group consisting of oxygen, nitrogen, and sulfur atoms, and specifically, includes pyrrolidinyl, piperidinyl, piperazinyl, tetrahydrofuranyl, tetrahydropyranyl, dihydropyranyl, tetrahydropyridinyl, dihydropyridinyl, morpholinyl, azepanyl, indolinyl, isoindolinyl, dihydroquinolinyl, and tetrahydroquinolinyl.
  • the number of substituents of any one of groups in the compound of Formula [I] is not limited, unless otherwise specified, as long as it is chemically acceptable, and for example, includes 1 to 10, 1 to 8, 1 to 6, 1 to 4, and 1 to 3.
  • ⁇ is amino or carbamoyl
  • the number of substituents on ⁇ is 1 or 2.
  • Substituents may bind to any atoms such as carbon atoms and heteroatoms as long as they are chemically acceptable.
  • substituteduent group (Ia) is the group consisting of: (a) alkyl-CO- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), (b) alkenyl-CO- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), (c) alkynyl-CO- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), (d) alkyl-O-CO- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), (e) alkyl-S- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), (f) alkyl-SO- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), (g) alkyl-SO 2 - that optionally has at least one group independently each group independently
  • substituted group (Ib) is the group consisting of: (a) halogen, (b) -CN, (c) -NO 2 , (d) -OH, (e) -CHO, (f) -COOH, (g) -SO 3 H, (h) -SH, (i) alkyl-O- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), (j) alkenyl-O- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), (k) alkynyl-O- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), (l) alkyl-COO- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), (m) cycloalkenyl-O- that optionally has at least one group independently selected from the substituent groups (I) and (II
  • the “substituent group (Ic)” is the group consisting of: (a) alkyl that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), (b) alkenyl that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), and (c) alkynyl that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb).
  • substituted group (IIa) is the group consisting of -CHO, alkyl-CO-, alkenyl-CO-, alkynyl-CO-, alkyl-O-CO-, alkyl-SO 2 -, cycloalkyl, cycloalkyl-O-, cycloalkenyl, cycloalkyl-CO-, cycloalkyl-O-CO-, aryl, aryl-CO-, aryl-O-CO-, aralkyl, aralkyl-CO-, aralkyl-O-CO-, heterocycle, heterocyclyl-CO-, heterocyclyl-O-CO-, mono- or di-(alkyl-CO)-carbamoyl, and mono- or di-alkylcarbamoyl.
  • substituteduent group (IIb) is the group consisting of halogen, -CN, -NO 2 , -OH, -COOH, -SO 3 H, -SH, -NH 2 , alkyl-O-, alkenyl-O-, alkynyl-O-, alkyl-COO-, alkyl-S-, alkyl-SO-, cycloalkenyl-O-, aryl-O-, aralkyl-O-, heterocyclyl-O-, mono- or di-alkylamino, mono- or di-(alkyl-CO)-amino, mono- or di-alkyl-O-carbonylamino, mono- or di-arylcarbonylamino, and mono- or di-aralkylcarbonylamino.
  • substituteduent group (IIc) is the group consisting of alkyl, alkenyl, and alkynyl.
  • Item 1 A compound of Formula [I]: or a salt thereof, wherein R 1 is 1) an optionally substituted 6- to 10-membered aryl, 2) an optionally substituted 5- to 10-membered heteroaryl, provided that when the heteroaryl is a tetrazolyl, the tetrazolyl should bind to the pyrrolidine ring via its carbon atom, or 3) -O-C 4-10 alkyl; a ring structure A of the following formula: is any one of the following formulae (A1) to (A3): wherein ring groups G 1 and G 2 of the following formulae: are each independently 6- to 10-membered aryl or 5- to 10-membered heteroaryl, which is optionally substituted with oxo; X 1 is N, CH, or C; the following structure: in the formula (A1) is a bond, wherein: 1) when X 1 is N, then the bond is a single bond, 2) when X 1 is CH,
  • R 1 is: 1) 6- to 10-membered aryl or 5- to 10-membered heteroaryl, which is optionally substituted with 1 to 3 groups independently selected from the group
  • Item 3 The compound of according to Item 1 or 2, or a salt thereof, wherein ring groups G 1 and G 2 are each independently any one of the following ring groups: wherein X 21 , X 22 , X 31 , X 32 , X 41 , X 42 , and X 51 are each independently N or CH, and X 61 is NH or O.
  • Item 4 The compound according to any one of Items 1 to 3, or a salt thereof, wherein ring groups G 1 and G 2 are each independently any one of the following ring groups.
  • Item 7 The compound according to Item 1, or a salt thereof, selected from the group consisting of the following compounds:
  • Item 8 The compound according to Item 1, selected from the group consisting of the following compounds or salts:
  • Item 9 A pharmaceutical composition comprising a compound according to any one of Items 1 to 8, or a salt thereof, and a pharmaceutically acceptable carrier.
  • Item 10 The composition according to Item 9, for use in treatment or prevention of a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
  • a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
  • Item 11 A medicament for use in treatment or prevention of a disease involving HDAC, comprising a compound according to any one of Items 1 to 8, or a salt thereof.
  • Item 12 A medicament for use in treatment or prevention of a disease involving HDAC2, comprising a compound according to any one of Items 1 to 8, or a salt thereof.
  • Item 13 The medicament according to Item 11 or 12, wherein the disease is selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
  • Item 14 A compound according to any one of Items 1 to 8, or a salt thereof, for use in treatment or prevention of a disease involving HDAC.
  • Item 15 A compound according to any one of Items 1 to 8, or a salt thereof, for use in treatment or prevention of a disease involving HDAC2.
  • Item 16 A compound according to any one of Items 1 to 8, or a salt thereof, for use in treatment or prevention of a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
  • Item 17 Use of a compound according to any one of Items 1 to 8, or a salt thereof, or a pharmaceutical composition according to Item 9 in the manufacture of a medicament for use in treatment or prevention of a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
  • a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
  • Item 18 A method of treating or preventing a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy in a subject in need thereof, comprising administering a therapeutically effective amount of a compound according to any one of Items 1 to 8, or a salt thereof, or a pharmaceutical composition according to Item 9 to the subject.
  • a ring structure A of the following formula: is any one of the following formulae: wherein G 1 , G 2 , R 21 , R 22 , R 23 , p, q, and r are the same as defined above.
  • m is preferably 1.
  • n is preferably 1.
  • p is preferably 0 or 1.
  • q is preferably 0 or 1.
  • Inert solvents used herein include, for example, hydrocarbons, halogenated hydrocarbons, alcohols, ethers, esters, ketones, amides, nitriles, sulfoxides, and water, which may be used in combination with any two or more of these solvents with optional ratios.
  • hydrocarbons include, for example, aliphatic hydrocarbons such as hexane and pentane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; and aromatic hydrocarbons such as benzene and toluene.
  • halogenated hydrocarbons herein include, for example, chloroform and dichloromethane.
  • Examples of "alcohols” herein include, for example, methanol, ethanol, 2-propanol, propanol, and tert-butanol.
  • Examples of “ethers” herein include, for example, chained ethers such as diethyl ether, diisopropyl ether, dibutyl ether, and diphenyl ether; and circular ethers such as 1,4-dioxane and tetrahydrofuran.
  • Examples of "esters” herein include, for example, ethyl acetate and ethyl propionate.
  • ketones herein include, for example, acetone, methyl ethyl ketone, and methyl isobutyl ketone.
  • amides herein include, for example, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone.
  • nitriles herein include, for example, acetonitrile and propionitrile.
  • sulfoxides herein include, for example, dimethyl sulfoxide.
  • Bases used herein include, for example, alkali metal hydroxides, alkali metal hydrides, alkali metal carboxylates, alkali metal carbonates, alkali metal hydrogencarbonates, alkali metal phosphates, aromatic amines, tertiary amines, metal amides, and metal alkoxides.
  • alkali metal hydroxides include, for example, sodium hydroxide, potassium hydroxide, and cesium hydroxide.
  • alkali metal hydrides include, for example, sodium hydride, potassium hydride, and cesium hydride.
  • alkali metal carboxylates herein include, for example, sodium acetate, potassium acetate, and sodium butyrate.
  • alkali metal carbonates include, for example, sodium carbonate, potassium carbonate, cesium carbonate, and lithium carbonate.
  • alkali metal hydrogencarbonates include, for example, sodium hydrogencarbonate, potassium hydrogencarbonate, and cesium hydrogencarbonate.
  • alkali metal phosphates include, for example, sodium phosphate and potassium phosphate.
  • aromatic amines include, for example, pyridine and lutidine.
  • tertiary amines include, for example, triethylamine, tripropylamine, tributylamine, diisopropylethylamine, cyclohexyldimethylamine, 4-dimethylaminopyridine, N,N-dimethylaniline, N-methylpiperidine, N-methylpyrrolidine, N-methylmorpholine, tetramethylethylenediamine, tetramethylpropylenediamine, and 1,8-diazabicyclo[5,4,0]undec-7-ene (diazabicycloundecene).
  • metal amides include, for example, lithium diisopropylamide and lithium hexamethyldisilazide.
  • metal alkoxides include, for example, sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium tert-butoxide, and sodium phenoxide.
  • Acids used herein include, for example, inorganic acids and organic acids.
  • inorganic acids include, for example, hydrochloric acid, sulfuric acid, nitric acid, hydrobromic acid, and phosphoric acid.
  • organic acids include, for example, acetic acid, trifluoroacetic acid, oxalic acid, phthalic acid, fumaric acid, tartaric acid, maleic acid, citric acid, succinic acid, methanesulfonic acid, p-toluenesulfonic acid, and 10-camphorsulfonic acid.
  • condensation agent examples include, for example, T3P; HATU; DCC; N-cyclohexyl-N’-morpholinoethylcarbodiimide; N-cyclohexyl-N’-(4-diethylaminocyclohexyl)carbodiimide; N,N’-diethylcarbodiimide; N,N’-diisopropylcarbodiimide; N,N-diisopropylethylamine; WSC or a hydrochloride salt thereof; N,N’-carbonylbis(2-methylimidazole); pentamethyleneketene-N-cyclohexylimine; diphenylketene-N-cyclohexylimine; ethoxyacetylene, 1-alkoxy-1-chloroethylene; trialkyl phosphite; ethyl polyphosphate; isopropyl polyphosphate; phosphoryl chloride; phosphorus
  • a condensation accelerator may be added.
  • a condensation accelerator used herein include, for example, 1-hydroxybenzotriazole (HOBt), N-hydroxysuccinimide (HOSu), 1-hydroxy-7-azabenzotriazole (HOAt), and hydroxy-3,4-dihydro-4-oxo-1,2,3-benzotriazine (HOOBt).
  • Examples of a "protecting group of hydroxy” used herein include, but not limited to, any protecting groups of hydroxy used in the field of synthetic organic chemistry, and include, for example, alkyl groups (e.g., methyl, ethyl, isopropyl, tert-butyl, trifluoromethyl, hydroxymethyl, 2-hydroxyethyl, acetylmethyl); alkenyl groups (e.g., ethenyl, 1-propenyl, 2-propenyl, 1-methyl-2-propenyl); alkynyl groups (e.g., ethynyl, 1-propynyl, 2-propynyl, 1-methyl-2-propynyl); formyl; alkyl (alkenyl) carbonyl groups (e.g., acetyl, propionyl, butyryl, isobutyryl, pentanoyl, pivaloyl, valeryl, isovaleryl, chloroacet
  • Examples of a “protecting group of carboxy” used herein include, but not limited to, any protecting groups of carboxy used in the field of synthetic organic chemistry, and include, for example, the “alkyl groups”, “alkenyl groups”, “alkynyl groups”, “aralkyl groups”, and “silyl groups” as above listed in the examples of the "protecting group of hydroxy” and similar groups thereof.
  • Examples of a “protecting group of amino” used herein include, but not limited to, any protecting groups of amino used in the field of synthetic organic chemistry, and include, for example, the “alkyl (alkenyl) carbonyl groups", “arylcarbonyl groups”, “alkoxycarbonyl groups”, “silyl groups”, “aralkyl groups”, “alkenyloxycarbonyl groups”, and “aralkyloxycarbonyl groups” as above listed in the "protecting group of hydroxy” and similar groups thereof.
  • Examples of a "protecting group of terminal acetylene” used herein include, but not limited to, any protecting groups of terminal acetylene used in the field of synthetic organic chemistry, and include, for example, the “silyl groups” as above listed in the "protecting group of hydroxy” and similar groups thereof.
  • Examples of a "leaving group" used herein include, for example, halogen (e.g., fluorine, chlorine, bromine, iodine), alkylsulfonyloxy groups (e.g., methylsulfonyloxy, ethylsulfonyloxy, trifluoromethylsulfonyloxy), and arylsulfonyloxy groups (e.g., benzenesulfonyloxy, p-toluenesulfonyloxy, 2,4,6-trimethylbenzenesulfonyloxy, 2-nitrobenzenesulfonyloxy, 4-nitrobenzenesulfonyloxy).
  • halogen e.g., fluorine, chlorine, bromine, iodine
  • alkylsulfonyloxy groups e.g., methylsulfonyloxy, ethylsulfonyloxy, trifluor
  • the reaction temperature in each step in the General Preparation typically ranges from -80 to 150°C.
  • the reaction time in each step typically ranges from 0.1 to 200 hours.
  • R 1a is hydroxy, an optionally substituted 6- to 10-membered aryl, an optionally substituted 5- to 10-membered heteroaryl, or -O-C 4-10 alkyl; R 1 and A are the same as defined above; and PG 1 is a protecting group of amino group as defined above.
  • Compound [I] may be prepared by coupling compound (1) and compound (2) in an inert solvent in the presence or absence of a base or acid, followed by deprotection of the PG 1 group.
  • Compound (1) and Compound (2) may be reacted under an amidation condition, followed by deprotection of the PG 1 group to give Compound [I].
  • R 1a is hydroxy
  • an alkylation step may be comprised further to convert the hydroxy group into a corresponding -O-alkyl group.
  • the amidation step herein may be conducted by methods commonly used in the art, and for example, Compound (1) and Compound (2) may be subjected to dehydration condensation in an inert solvent in the presence of a condensation agent and a base in the presence or absence of a condensation accelerator.
  • the deprotection step herein may be conducted by methods commonly used in the art, and for example, the compound prepared in the amidation step may be deprotected in an inert solvent or without any solvent in the presence of an acid (e.g., hydrochloric acid and trifluoroacetic acid), when PG 1 is tert-butoxycarbonyl (Boc) group.
  • the alkylation step herein may be conducted by methods commonly used in the art, and for example, the compound after the deprotection step may be reacted with alkyl-LG in an inert solvent in the presence of a base, where LG is a leaving group, when R 1a is hydroxy.
  • Compound [I] when Compound [I] has an isoindoline-carbonyl group, Compound [I] may be prepared by, for example, the following scheme.
  • Scheme 2 In the scheme, Ar is an optionally substituted 6- to 10-membered aryl or an optionally substituted 5- to 10-membered heteroaryl;
  • B(OR') 2 is B(OH) 2 or B(O-alkyl) 2 wherein two O-alkyl groups may be optionally combined together with boron so that B(O-alkyl) 2 may form, for example, Bpin; and s is 0 to 2.
  • the amidation and deprotection steps herein may be conducted in a similar manner described in the above.
  • the trifluoromethanesulfonylation step may be conducted by methods commonly used in the art, and for example, the ketone compound may be reacted in the presence of N-phenyl-bis(trifluoromethanesulfonimide) in an inert solvent in the presence of a base.
  • the coupling step may be conducted by methods commonly used in the art, and for example, the compound having the trifluoromethanesulfonyloxy group may be subjected to the Suzuki Cross-coupling Reaction with boronic acid or boronic ester in the presence of a palladium compound such as Pd(0) including Pd(PPh 3 ) 4 and Pd/C and a ligand such as a phosphine ligand including Sphos and Xphos in an inert solvent in the presence of a base.
  • a palladium compound such as Pd(0) including Pd(PPh 3 ) 4 and Pd/C
  • a ligand such as a phosphine ligand including Sphos and Xphos in an inert solvent in the presence of a base.
  • the hydrogenation step may be conducted by methods commonly used in the art, and for example, may be conducted in the presence of a hydrogen source, for example, hydrogen gas and a metal catalyst, for example, palladuim on carbon (Pd/C) and platinum oxide (PtO 2 ).
  • a hydrogen source for example, hydrogen gas
  • a metal catalyst for example, palladuim on carbon (Pd/C) and platinum oxide (PtO 2 ).
  • Compound (1) may be commercially available or prepared by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
  • Compound (1) may be prepared by the following scheme.
  • Scheme 3 In the scheme, B(OR') 2 and R 1a are the same as defined above.
  • Step 1 Compound (1-1) may be subjected to the Suzuki Cross-coupling Reaction with R 1a B(OR') 2 in the presence of a palladium catalyst and a ligand in an inert solvent in the presence of a base to give Compound (1-2).
  • Compound (1-2) may be hydrogenated in the presence of a palladium catalyst, e.g., Pd/C, to give Compound (1-3).
  • Compound (1-3) may be hydrolyzed to give Compound (1).
  • Solvents and other reagents, if any, and reaction conditions used in these steps may be selected from those described in the above.
  • R 1a is a halogenated phenyl group
  • Compound (1) may be prepared by, for example, the following scheme.
  • Scheme 4 In the scheme, B(OR') 2 is the same as defined above. Each step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
  • Compound (2) may be commercially available or prepared by methods commonly used in the art or by one or any combinations of the following illustrative schemes.
  • Scheme 6 This step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
  • X is halogen
  • Ar is an optionally substituted C 6-10 aryl
  • u is 0 to 2.
  • Compound [I] can be prepared by any of the above schemes or processes, any analogous or equivalent methods thereof, or any combinations thereof. Compound [I] may also be prepared, if necessary, with modifications of the preparations, types, numbers, and/or positions of substituents in the starting materials and/or intermediates, or the reaction conditions herein, in view of commonly known methods.
  • Compound [I] includes derivatives of Compound [I] which can be prepared by any known reactions such as alkylation, acylation, amidation, esterification, etherification, halogenation, hydroxylation, amination, aryl coupling, condensation including carbon extension reaction, addition, substitution, oxidation, reduction, dehydration, and hydrolysis.
  • starting materials used herein may be commercially available, or may be produced by known methods or analogous methods thereof.
  • any functional groups of starting materials and intermediates in the above respective steps may be protected with appropriate protective groups before a particular reaction, and the protective groups may be deprotected after the particular reaction, if necessary, using any known methods (e.g., methods described in P. G. M. Wuts and T. W. Greene, “Greene's Protective Groups in Organic Synthesis” (4th ed., 2006)).
  • any intermediates and final products in the above respective steps may be directly used in subsequent steps, or may be isolated and purified after completion of reactions.
  • these compounds may be isolated and purified by cooling reaction mixtures, followed by isolation procedures such as filtration, concentration, and extraction, to isolate crude reaction products, which are then subject to general purification procedures such as column chromatography and recrystallization.
  • Any starting materials, intermediates, and final products in the above respective steps as well as Compound [I] encompass corresponding compounds in the form of a solvate, such as a hydrate and ethanolate.
  • Compound [I] may form a solvate thereof which is also encompassed by the present invention.
  • Any starting materials, intermediates, and final products as well as Compound [I] encompass corresponding geometric isomers, stereoisomers, optical isomers, and tautomers. These various isomers can be separated by any known separation methods. For example, a racemic compound can be separated to a sterically pure isomer by common optical resolution (e.g., optical resolution by crystallization and direct optical resolution by chromatography). An optically active compound can also be prepared with an appropriate optically active starting material. Any prepared compounds may be isolated as chemically stable tautomers thereof.
  • Compound [I] includes a pharmaceutically acceptable salt form thereof.
  • the salt used herein includes salts with any commonly used pharmaceutically acceptable acids, bases, and amino acids.
  • the acids include inorganic acids such as hydrochloric acid, hydrobromic acid, nitric acid, sulfuric acid, and phosphoric acid; and organic acids such as methanesulfonic acid, p-toluenesulfonic acid, acetic acid, citric acid, tartaric acid, maleic acid, fumaric acid, malic acid, and lactic acid.
  • the bases include inorganic bases such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, and potassium hydrogencarbonate; organic bases such as methylamine, diethylamine, trimethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, ethylenediamine, tris(hydroxymethyl)methylamine, dicyclohexylamine, N,N'-dibenzylethylenediamine, guanidine, pyridine, picoline, and choline; and ammonium salts.
  • the amino acids include lysine, arginine, asparagine acid, and glutamic acid.
  • Compound [I] includes any compounds wherein one or more atoms are replaced with one or more isotopic atoms.
  • isotopic atoms include deuterium ( 2 H, D), tritium ( 3 H), 13 C, 14 N, and 18 O.
  • Compound [I] also includes a prodrug form thereof.
  • the "prodrug” refers to any compounds that are chemically or metabolically converted into Compound [I] as the active metabolite under physiological conditions after administration in vivo, and includes those which a part of substituents of Compound [I] is chemically modified.
  • Prodrugs may be utilized for several purposes including enhancement of water solubility, improvement of bioavailability and/or stability, reduction of side effects, adjusted metabolism, sustained efficacy, and drug selectivity against target sites.
  • Substituents for modification to form a prodrug include any reactive functional groups such as -OH, -COOH, and amino. Such modifications of functional groups may be optionally selected from the "substituents" used herein.
  • Compound [I] may be in the form of a pharmaceutically acceptable co-crystal or co-crystal salt.
  • Co-crystals and co-crystal salts can be manufactured appropriately by well-known co-crystallization methods.
  • Compound [I] may be useful for an HDAC inhibitor with good brain penetration, and may be a new and promising drug for treatment or prevention of diseases involving HDACs, e.g., Class I HDACs such as HDAC2.
  • Histone acetylation plays an important role in CNS functions such as neuronal differentiation, memory formation, drug addiction, and depression.
  • Compound [I] may be useful in treating neurological disorders. Neurological disorders include chronic or acute diseases, and familial or sporadic diseases.
  • HDACs examples include central nervous system diseases including neurological and/or neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson disease (PD), Lewy body dementia, frontotemporal dementia (FTD), frontotemporal lobar dementia, and amyotrophic lateral sclerosis (ALS, also known as motor neurone disease (MND) or Lou Gehrig’s disease), cognitive dysfunction, Rubinstein-Taybi syndrome, and spinocerebellar degeneration such as Friedreich's ataxia; psychiatric diseases such as schizophrenia, mania, depression, and memory loss; acute and chronic cerebral infarction and brain damage; acute and chronic spinal cord injury; cerebral tumors such as gliomas; pain such as peripheral pain and neuropathic pain; hereditary neuropathy such as hereditary motor and sensory neuropathy including Charcot-Marie-Tooth disease, hereditary sensory neuropathy, hereditary motor neuropathy, and hereditary sensory and autonomic neuropathy; cancers such as gastric cancer, prostate cancer, colorectal cancer,
  • AD Alzheimer'
  • Compound [I] When administered to a subject, Compound [I] may be formulated into a medical formulation (also referred to as a "pharmaceutical composition" hereinafter) in various forms depending on therapeutic purposes, ages, genders, disease states of subjects, and other conditions.
  • a medical formulation also referred to as a "pharmaceutical composition” hereinafter
  • examples of the formulation include tablets (such as sugar-coated tablets, enteric coated tablets, and film-coated tablets), pills, powders, liquids, suspensions, emulsions, granules, capsules, suppositories, and intramuscular, intradermal, subcutaneous, or intraperitoneal injections (such as liquids and suspensions).
  • the medical formulation used herein comprises Compound [I] and is prepared by combining Compound [I] and a pharmaceutically acceptable carrier, followed by formulation.
  • the carrier used herein includes commonly used carriers including excipients such as glucose, lactose, sucrose, sodium chloride, glucose, urea, starch, cacao butter, calcium carbonate, hydrogenated vegetable oil, kaolin, talc, and crystalline cellulose; binders such as water, ethanol, propanol, simple syrup, glucose solution, starch solution, gum arabic powders, tragacanth powders, gelatin solution, carboxymethyl cellulose, shellac, methyl cellulose, potassium phosphate, and polyvinylpyrrolidone; disintegrants such as dry starch, sodium alginate, agar powders, laminaran powders, sodium hydrogencarbonate, calcium carbonate, polyoxyethylene sorbitan fatty acid esters, sodium lauryl sulfate, monoglyceride stearate, starch, and lactose;
  • a medical formulation used herein typically comprises 1 to 70% by weight of a compound of Formula [I] to the formulation.
  • a dosage amount of a compound of Formula [I] comprised in a medical formulation herein may vary and may be optimized depending on dosage regimens, ages, genders, and the extent of diseases of patients, and other conditions; the amount ranges, for example, from 0.01 to 100 mg/kg, preferably 0.1 to 50 mg/kg, of body weight per day in a single dose or multiple doses.
  • Compound [I] may be used in combination with at least one therapeutic or preventive agent useful for diseases for which Compound [I] is thought to be effective.
  • the agent includes medicaments useful for diseases selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumors, pain, and hereditary neuropathy.
  • the agent includes medicaments useful for diseases selected from cancers, fungal diseases, and infections.
  • the agent may be administered in combination with Compound [I] simultaneously, and/or separately, such as continuously or with a suitable interval in between.
  • the agent may be formulated into a separate formulation from a formulation comprising Compound [I] or into a single formulation comprising both the agent and Compound [I].
  • the "r.t.” in the Examples below basically refers to from about 10°C to about 35°C.
  • the ratios in mixed solvents refer to the volume ratio unless otherwise specified.
  • % refers to % by weight unless otherwise specified.
  • 1 H NMR proto nuclear magnetic resonance spectrum
  • Fourier transform NMR any one of Bruker AVANCE III 400 (400 MHz), Bruker AVANCE III 500 HD (500 MHz)), and Bruker AVI 400MHz with a QNP probe, Z gradient.
  • silica gel column chromatography aminopropylsilane-bonded silica gels were used when the term "basic" is described.
  • Absolute configurations of compounds were determined by known X-ray crystallography (e.g., Shigeru Ooba and Shigenobu Yano, "Kagakusha no tame no Kiso-Koza 12 X-ray crystallography” (1st ed., 1999)) or estimated from the empirical rules of Shi asymmetric epoxidation (Waldemar Adam, Rainer T. Fell, Chantu R. Saha-Moller and Cong-Gui Zhao: Tetrahedron: Asymmetry 1998, 9, 397-401. Yuanming Zhu, Yong Tu, Hongwu Yu, Yian Shi: Tetrahedron Lett. 1988, 29, 2437-2440).
  • the resultant residue was purified by silica gel column chromatography (Hexane : AcOEt) to give the product.
  • the resultant residue was purified by silica gel column chromatography (Hexane : AcOEt) to give the product.
  • tert-butyl (R)-3-(bromomethyl)pyrrolidine-1-carboxylate (1.00 g) in DME (dry) (25 mL), 2-bromo-5-methyl thiazole (0.401 ml), tris(trimethylsilyl)silane (1.168 ml), (4,4'-di-t-butyl-2,2'-bipyridine)bis[3,5-difluoro-2-(5-trifluoromethyl-2-pyridinyl-kN)phenyl-kC]iridium (III) hexafluorophosphate (0.042 g) and 2,6-lutidine (0.882 ml) were added to the mixture.
  • Reference Example 8 2-((6-Methoxyisoindolin-5-yl)methyl)quinoline dihydrochloride A mixture of 2-benzyl-5-bromo-6-methoxyisoindoline (2.00 g), Pd 2 (dba) 3 (0.288 g), xantphos (0.546 g) and potassium 2-(quinolin-2-yl)acetate (4.25 g) was heated at 130°C for 5 h under N 2 atmosphere. After cooling to r.t., H 2 O was added and the aqueous solution was extracted with AcOEt. The combined organic layers were washed with brine, dried over Na 2 SO 4 , filtered, and concentrated.
  • the aqueous phase was basified with 5 N NaOH to pH 10 or below and extracted with AcOEt. The combined organic layers were washed with brine, dried over Na 2 SO 4 , filtered, concentrated and dried to give 232 mg of 4-chloro-N-(2-(isoindolin-5-yl)ethyl)aniline.
  • the reaction mixture was purified by silica gel column chromatography (Hexane : AcOEt) to give the product.
  • a mixture of the obtained product and Silia Cat Pd(0) (80 mg) in AcOEt (10 mL) was stirred at r.t. for 5 h under H 2 atmosphere.
  • the reaction mixture was filtered through Celite and the filtrate was concentrated in vacuo.
  • the resultant residue was purified by amino silica gel column chromatography (Hexane : AcOEt) to give the product.
  • MeOH 3 ml
  • 5 N NaOH (0.23 mL
  • the reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo.
  • the resultant residue was purified by silica gel column chromatography (hexane:AcOEt) to give the product.
  • the resultant residue was purified by silica gel column chromatography (hexane:AcOEt) to give the product.
  • EtOH 100 ml
  • 5 N NaOH 8.92 ml
  • the reaction mixture was stirred for 3 h at r.t.
  • the reaction mixture was neutralized with 5 N HCl at 0°C.
  • the volatiles were evaporated in vacuo.
  • the resultant aqueous phase was extracted with AcOEt.
  • Example 1 ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(isoindolin-2-yl)methanone hydrochloride
  • tert-butyl (2R)-2-(2,3-dihydro-1H-isoindole-2-carbonyl)-4-(trifluoromethanesulfonyloxy)-2,5-dihydro-1H-pyrrole-1-carboxylate 400 mg
  • 3-chlorophenylboronic acid (162 mg)
  • Pd(dtbpf)Cl 2 (11.3 mg)
  • 2M Na 2 CO 3 (1 mL).
  • the reaction was stirred under N 2 at 100°C for 1 hour.
  • the reaction was partitioned between water and AcOEt, the combined organics were concentrated in vacuo and the residue purified by silica gel column chromatography (petrol:AcOEt) to give the product (182 mg).
  • the obtained product (182 mg) and PtO 2 (18 mg) were combined in MeOH (5 mL) and the suspension was stirred at r.t. under H 2 for 3 hours.
  • the reaction was filtered through Celite, the filtrate was concentrated and the residue was purified by silica gel column chromatography (petrol:AcOEt) to give the product (54 mg).
  • Example 2 and Example 3 5-(4-((3S,5R)-5-(Isoindoline-2-carbonyl)pyrrolidin-3-yl)phenyl)pyrrolidin-2-one (Isomer 1 and Isomer 2)
  • To a solution of 1-(tert-butyl) 2-methyl (R)-4-(((trifluoromethyl)sulfonyl)oxy)-2,5-dihydro-1H-pyrrole-1,2-dicarboxylate (1.3 g) in dioxane (15 mL) were added Pd(dppf)Cl 2 (72 mg,), KOAc (1.0 g) and bis(pinacolato)diboron (1.5 g) and the reaction was stirred under N 2 at 90°C overnight.
  • the two isomers were separated by chiral HPLC (Waters Thar Investigator with Waters 2998 UV/Vis PDA detector, YMC AMYLOSE-C 10 x 250mm, 5 ⁇ m 55/45 MeOH (0.1% DEA) / CO 2 , 15 ml/min, 120 bar, 40°C).
  • the one isomer eluted firstly was identified as Isomer 1a
  • the other isomer eluted secondly was identified as Isomer 2a, respectively.
  • Isomer 1a was treated with 4M HCl in dioxane to form the hydrochloride salt that was identified as Isomer 1 (Example 2).
  • Isomer 2a was also treated with 4M HCl in dioxane to form its hydrochloride salt form that was then identified as Isomer 2 (Example 3).
  • the reaction was stirred under N 2 at 100°C for 2 hours.
  • the reaction was partitioned between water and AcOEt, the organic phase was concentrated and the residue was purified by silica gel column chromatography (petrol:AcOEt) to give the product (217 mg).
  • the obtained product (217 mg) and PtO 2 (22 mg) were combined in MeOH (5 mL).
  • the suspension was stirred at r.t. under H 2 for 3 hours.
  • the reaction mixture was filtered through Celite, the filtrate was concentrated and the residue was purified by reversed phase silica gel column chromatography (KP-C18, water:acetonitrile) to give the product (36 mg).
  • Example 5 Isoindolin-2-yl((2R,4S)-4-phenylpyrrolidin-2-yl)methanone hydrochloride To a suspension of (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid (240 mg), isoindoline (0.112 ml), WSC (205 mg) and HOBt (164 mg) in DMF (5 ml) was added DIPEA (0.360 ml). The reaction mixture was stirred overnight. The reaction mixture was diluted with AcOEt and water and extracted with AcOEt.
  • Example 6 ((2R,4S)-4-Phenylpyrrolidin-2-yl)(3-(pyridin-2-ylmethyl)pyrrolidin-1-yl)methanone dihydrochloride
  • (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid 150 mg
  • 2-(pyrrolidin-3-ylmethyl)pyridine dihydrochloride 145 mg
  • WSC (128 mg
  • HOBt 102 mg
  • the reaction mixture was diluted with AcOEt and water and extracted with AcOEt. The combined organic layers were washed with water and brine, and dried over Na 2 SO 4 , filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (AcOEt : MeOH) to give the product. To a solution of the obtained product in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. The resultant residue was dissolved in water (5 mL), basified with sat. NaHCO 3 aq. and extracted with AcOEt.
  • Example 7 2-(4-((2R,4S)-4-Phenylpyrrolidine-2-carbonyl)piperazin-1-yl)nicotinonitrile dihydrochloride
  • (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid 150 mg
  • 2-(1-Piperazinyl)-3-pyridinecarbonitrile 116 mg
  • WSC (128 mg)
  • HOBt 102 mg
  • Example 8 2-(4-((2R,4S)-4-(3-Chlorophenyl)pyrrolidine-2-carbonyl)piperazin-1-yl)nicotinonitrile dihydrochloride
  • (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid 200 mg
  • 2-(1-Piperazinyl)-3-pyridinecarbonitrile 139 mg
  • WSC 153 mg
  • HOBt 122 mg
  • the reaction mixture was diluted with AcOEt and water and extracted with AcOEt. The combined organic layers were washed with water and brine, dried over Na 2 SO 4 , filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane : AcOEt) to give the product. To a solution of the obtained product (290 mg) in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo.
  • Example 9 2-(2-((2R,4S)-4-(3-Chlorophenyl)pyrrolidine-2-carbonyl)-6-methoxyisoindolin-5-yl)-N-phenylacetamide hydrochloride
  • (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid 120 mg
  • 2-(6-methoxyisoindolin-5-yl)-N-phenylacetamide hydrochloride 141 mg
  • WSC 92 mg
  • HOBt 73.3 mg
  • the reaction mixture was stirred for 3 days at r.t.
  • the reaction mixture was diluted with AcOEt and water and extracted with AcOEt.
  • the combined organic layers were washed with water and brine and dried over Na 2 SO 4 , filtered off, concentrated in vacuo.
  • the resultant residue was purified by silica gel column chromatography (hexane : AcOEt) to give the product.
  • To a solution of the obtained product in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml).
  • the reaction mixture was stirred at r.t. overnight.
  • the volatiles were evaporated in vacuo.
  • the resultant residue was dissolved in small amount of DCM and IPE was added to the solution.
  • Example 10 ((2R,4S)-4-Phenylpyrrolidin-2-yl)(4-(thieno[2,3-c]pyridin-7-yl)piperazin-1-yl)methanone dihydrochloride
  • (2R,4S)-1-(tert-butoxycarbonyl)-4-phenylpyrrolidine-2-carboxylic acid 150 mg
  • 7-(piperazin-1-yl)thieno[2,3-c]pyridine hydrochloride 158 mg
  • WSC (128 mg
  • HOBt 102 mg
  • the reaction mixture was diluted with AcOEt and water and extracted with AcOEt. The combined organic layers were washed with water and brine, dried over Na 2 SO 4 , filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane : AcOEt) to give 233 mg of the product. To a solution of the obtained product (230 mg) in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo.
  • Example 11 ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(4-(thieno[2,3-c]pyridin-7-yl)piperazin-1-yl)methanone dihydrochloride
  • (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid 110 mg
  • 7-(piperazin-1-yl)thieno[2,3-c]pyridine hydrochloride 104 mg
  • WSC 84 mg
  • HOBt 67.2 mg
  • the reaction mixture was stirred for 3 days at room temperature.
  • the reaction mixture was diluted with AcOEt and water and extracted with AcOEt.
  • the combined organic layers were washed with water and brine, dried over Na 2 SO 4 , filtered off and concentrated in vacuo.
  • the resultant residue was purified by silica gel column chromatography (hexane : AcOEt).
  • To a solution of the obtained product in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml).
  • the reaction mixture was stirred at room temperature overnight. The volatiles were evaporated in vacuo.
  • Example 12 ((2R,4S)-4-Phenylpyrrolidin-2-yl)(4-(thieno[2,3-c]pyridin-7-yl)piperidin-1-yl)methanone dihydrochloride
  • (2R,4S)-1-(tert-butoxycarbonyl)-4-phenylpyrrolidine-2-carboxylic acid 50 mg
  • 7-(piperidin-4-yl)thieno[2,3-c]pyridine dihydrochloride 60.0 mg
  • WSC 42.8 mg
  • HOBt 34.2 mg
  • the reaction mixture was diluted with water and extracted with AcOEt. The combined organic layers were washed with water and brine, dried over Na 2 SO 4 , filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane : AcOEt) to give the product. To a solution of the obtained product in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo.
  • Example 13 (4-(Benzo[b]thiophen-7-yl)piperazin-1-yl)((2R,4S)-4-(3-chlorophenyl)pyrrolidin-2-yl)methanone dihydrochloride
  • (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid 120 mg
  • 1-(benzo[b]thiophen-7-yl)piperazine dihydrochloride 129 mg
  • WSC 92 mg
  • HOBt 73.3 mg
  • the reaction mixture was stirred for 3 days at r.t.
  • Example 14 (5-Methoxy-6-(2-(phenylamino)ethyl)isoindolin-2-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone dihydrochloride
  • the title compound was obtained by similar procedures to Example 5.
  • Example 15 ((2R,4S)-4-Phenylpyrrolidin-2-yl)(4-(thieno[3,2-d]pyrimidin-4-yl)piperazin-1-yl)methanone dihydrochloride
  • the title compound was obtained by similar procedures to Example 5.
  • Example 16 (4-(3-(Furan-3-yl)pyridin-2-yl)piperazin-1-yl)((2R,4S)-4-(6-methoxynaphthalen-2-yl)pyrrolidin-2-yl)methanone dihydrochloride
  • (2R,4S)-1-(tert-butoxycarbonyl)-4-(6-methoxynaphthalen-2-yl)pyrrolidine-2-carboxylic acid (78 mg)
  • 1-(3-(furan-3-yl)pyridin-2-yl)piperazine dihydrochloride 95 mg
  • Example 17 ((2R,4S)-4-Phenylpyrrolidin-2-yl)(4-(thieno[2,3-c]pyridin-7-yl)-3,6-dihydropyridin-1(2H)-yl)methanone
  • (2R,4S)-1-(tert-butoxycarbonyl)-4-phenylpyrrolidine-2-carboxylic acid 110 mg
  • 7-(1,2,3,6-tetrahydropyridin-4-yl)thieno[2,3-c]pyridine hydrochloride 131 m
  • WSC 94 mg
  • HOBt 75 mg
  • Example 18 (4-(7-Chloroisoquinolin-1-yl)piperazin-1-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone dihydrochloride
  • the title compound was obtained by similar procedures to Example 5.
  • Example 19 ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(4-(3-methylthieno[2,3-c]pyridin-7-yl)piperazin-1-yl)methanone dihydrochloride
  • the title compound was obtained by similar procedures to Example 5.
  • Example 20 ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(4-(3-(furan-3-yl)-4-methylpyridin-2-yl)piperazin-1-yl)methanone hydrochloride
  • the title compound was obtained by similar procedures to Example 16.
  • Example 21 ((S)-3-((5-Methylthiazol-2-yl)methyl)pyrrolidin-1-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone hydrochloride
  • the title compound was obtained by similar procedures to Example 16.
  • Example 22 ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(5-hydroxy-6-(quinolin-2-ylmethyl)isoindolin-2-yl)methanone dihydrochloride
  • BBr 3 (1M in DCM)
  • Example 23 ((2R,4R)-4-(2-Ethylbutoxy)pyrrolidin-2-yl)(4-(3-(thiophen-2-yl)pyridin-2-yl)piperazin-1-yl)methanone hydrochloride
  • (2R,4R)-1-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid 700 mg
  • 1-(3-(thiophen-2-yl)pyridin-2-yl)piperazine dihydrochloride (1252 mg) in DCM (20 ml) were added TEA (2.11 ml) followed by 50% T3P in AcOEt solution (2.70 ml).
  • Example 24 (5-(2-((4-Chlorophenyl)amino)ethyl)isoindolin-2-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone dihydrochloride
  • the title compound was obtained by similar procedures to Example 16.
  • Example 25 5-(Furan-3-yl)-6-(4-((2R,4S)-4-phenylpyrrolidine-2-carbonyl)piperazin-1-yl)pyridin-2(1H)-one
  • (2R,4S)-1-(tert-butoxycarbonyl)-4-phenylpyrrolidine-2-carboxylic acid 227 mg
  • 1-(3-(furan-3-yl)-6-methoxypyridin-2-yl)piperazine hydrochloride 300 mg
  • TEA 0.544 ml
  • 50% T3P in AcOEt solution
  • Example 26 2,2'-(2-((2R,4S)-4-Phenylpyrrolidine-2-carbonyl)isoindoline-5,6-diyl)dibenzonitrile hydrochloride
  • the title compound was obtained by similar procedures to Example 16.
  • Example 27 ((2R,4S)-4-(3-Cyclopropylphenyl)pyrrolidin-2-yl)(4-(3-(furan-3-yl)pyridin-2-yl)piperazin-1-yl)methanone dihydrochloride
  • the title compound was obtained by similar procedures to Example 16.
  • Example 28 2-(2-((2R,4S)-4-(3-Chlorophenyl)pyrrolidine-2-carbonyl)isoindolin-5-yl)-3-fluorobenzonitrile hydrochloride The title compound was obtained by similar procedures to Example 16.
  • Example 29 2-(2-((2R,4S)-4-(3-Chlorophenyl)pyrrolidine-2-carbonyl)isoindolin-5-yl)-4-methoxynicotinonitrile
  • the title compound was obtained by similar procedures to Example 16.
  • Example 30 (4-(3-(Furan-3-yl)pyridin-2-yl)piperazin-1-yl)((2R,4S)-4-(3-propylphenyl)pyrrolidin-2-yl)methanone hydrochloride
  • the title compound was obtained by similar procedures to Example 16.
  • Example 31 (4-(3-(Furan-3-yl)pyridin-2-yl)piperazin-1-yl)((2R,4S)-4-(3-(trifluoromethyl)phenyl)pyrrolidin-2-yl)methanone hydrochloride
  • the title compound was obtained by similar procedures to Example 16.
  • Example 32 ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(4-(6-chloroquinolin-4-yl)piperazin-1-yl)methanone dihydrochloride
  • the title compound was obtained by similar procedures to Example 5.
  • Example 33 N-(6-Methoxy-2-((2R,4S)-4-phenylpyrrolidine-2-carbonyl)isoindolin-5-yl)-2-(4-methoxyphenyl)acetamide hydrochloride
  • Example 34 ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(4-(naphthalen-1-yl)piperazin-1-yl)methanone hydrochloride
  • the title compound was obtained by similar procedures to Example 5.
  • Example 35 (4-(2-(Furan-3-yl)phenyl)piperazin-1-yl)((2R,4S)-4-(6-methoxynaphthalen-2-yl)pyrrolidin-2-yl)methanone hydrochloride
  • the title compound was obtained by similar procedures to Example 16.
  • Example 36 N-(6-((3S,5R)-5-(Isoindoline-2-carbonyl)pyrrolidin-3-yl)naphthalen-2-yl)acetamide hydrochloride A mixture of tert-butyl (R)-2-(isoindoline-2-carbonyl)-4-(((trifluoromethyl)sulfonyl)oxy)-2,5-dihydro-1H-pyrrole-1-carboxylate (523 mg), N-(6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)naphthalen-2-yl)acetamide (458 mg), 2 M Na 2 CO 3 aq.
  • Example 37 (4-(3-(1H-Pyrrol-2-yl)pyridin-2-yl)piperazin-1-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone dihydrochloride
  • (2R,4S)-1-(tert-butoxycarbonyl)-4-phenylpyrrolidine-2-carboxylic acid 510 mg
  • 1-(3-bromopyridin-2-yl)piperazine 509 mg
  • TEA 1.220 ml
  • Example 38 (4-(3-(Furan-3-yl)pyrazin-2-yl)piperazin-1-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone hydrochloride
  • the title compound was obtained by similar procedures to Example 16.
  • Example 39 N-(6-((3S,5R)-5-(Isoindoline-2-carbonyl)pyrrolidin-3-yl)quinolin-2-yl)acetamide The title compound was obtained by similar procedures to Example 36.
  • Test Example 1 HDAC2 enzyme assay (in vitro) HDAC2 inhibition activity was performed according to the protocol of HDAC assay kits (purchased from BPS Bioscience). HDAC Assay Buffer (BPS catalog number 50031), HDAC Developer (BPS catalog number 50030), and HDAC Substrate (BPS number 50037) were used in this experiment. Compounds for testing were diluted in DMSO to 100 fold the final concentration (100, 30, 10, 3, 1, 0.3, 0.1, 0.03, 0.01, 0 ⁇ M) dilution series was made in triplicate. The compounds were diluted in HDAC Assay Buffer to 5 fold their final concentration.
  • the HDAC enzymes were diluted to 5 fold their final concentration in HDAC Assay Buffer on ice.
  • the HDAC substrate were diluted in HDAC Assay Buffer at 5 fold their final concentration.
  • the final enzyme concentration used in these assays were 0.2 ng/ml (HDAC2).
  • Ten ⁇ L of compound and 20 ⁇ L of HDAC buffer, 10 ⁇ L of enzyme and 10 ⁇ L of substrate were mixed and incubated together in U96-well black plate (Thermo Scientific) in triplicate at room temperature for 2 hours.
  • Fifty ⁇ L of HDAC developer solution was mixed and incubated at room temperature for 30 minutes.
  • the fluorescence (355 nm, Emission: 430 nm) was measured by SpectraMax M2e, SoftMax(R) Pro (Molecular Devices).
  • the IC 50 was determined using Graph Pad Prims by a four parameter curve fit. IC 50 ⁇ 1 ⁇ M: ***; 1 ⁇ M ⁇ IC 50 ⁇ 10 ⁇ M: **; 10 ⁇ M ⁇ IC 50 ⁇ 30 ⁇ M: *
  • Test Example 2 Cell culture and Purification of histone protein from the cell SK-N-SH (Human Neuroblastoma) was used in this experiment.
  • the cell line was purchased from the American Type Culture Collection.
  • SK-N-SH was grown in DMEM media (Gibco) supplemented with 10% FBS (Gibco), 1% Glutamine and 1% P/S (Gibco).
  • DMEM media Gibco
  • FBS Gibco
  • Glutamine 1% Glutamine
  • P/S 1% P/S
  • TEB Triton Extraction Buffer: PBS containing 0.5% Triton X 100 (v/v), 2 mM phenylmethylsulfonyl fluoride (PMSF), 0.02% (w/v) NaN 3 ).
  • the cell was lysed on ice for 30 minutes with gentle stirring and centrifuged to spin down the nuclei. The supernatant was remove and discard. The pellet was washed by TEB twice. Two hundreds ⁇ L of 0.2 N HCl was added to the samples and rotate at 4°C for 2 hours. The sample was centrifuged with max speed for 15 min and the supernatant was collected in another tube and neutralize with using 1N NaOH. This sample was used to the immunochemical detection.
  • Test Example 3 Oral administration, sampling of blood and brain All mice were maintained in a 12-h light/dark cycle at 23 ⁇ 2°C with free access to water and standard mouse chow. Male C57BL/6 mice (purchased from Charles River Laboratories Japan) were fasted overnight. Screening compounds were dissolved in 5% arabic gum in water for pharmacokinetic (PK) study. Two animals per experimental arm administrated the compounds solution by oral gavage. Blood was collected via retro orbital puncture into K2EDTA tubes at 0 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 6 hours and 24 hours after dosing from a mouse.
  • PK pharmacokinetic
  • the brains were harvested after anesthetization at 0 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 6 hours and 24 hours after dosing from a mouse.
  • the blood was centrifuged at 2,000 g for 5 minute at 4°C to obtain plasma.
  • Test Example 4 Pharmacokinetic study 1.1 Determination of Compound in Mouse Plasma and Brain Homogenates The compound in mouse plasma and brain homogenates was quantified with the high-performance liquid chromatographic-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method. 1.1.1 Preparation of Standard Solutions The compound was dissolved in dimethylsulfoxide (DMSO) at 1 mg/mL. This solution was diluted with methanol to prepare the standard solutions at 0.05 to 50 ⁇ g/mL.
  • DMSO dimethylsulfoxide
  • Tandem mass spectrometry (MS/MS) analysis was carried out with the 4000QTRAP LC/MS/MS system (AB SCIEX) equipped with an ESI source and a switching valve (Valco Instruments Co Inc). 1.1.6 Analytical Conditions Chromatographic separation was achieved on an XBridge C18 (3.5 ⁇ m, 2.1 mmID x 50 mm, Waters Corp). A binary gradient was formed with solvents A; 10 mmol/L ammonium acetate aqueous solution and B; acetonitrile at a flow rate of 0.55 mL/min. The ionization method was electrospray ionization with a positive mode.
  • Test Example 5 Purification of histone protein from the mouse brain
  • the brain of mice (approximately 100 ⁇ g) obtained in Test Example 3 was homogenized in 1 ml of TEB into a 1.5 mL tube with 21G syringe repeatedly passed through and then an ultrasonic Homogenizer for 1 minute.
  • the sample was incubated on ice and centrifuged with max speed for 15 min.
  • the cell was lysed on ice for 10 minutes with gentle stirring and centrifuged to spin down the nuclei.
  • the supernatant was remove and discard.
  • the pellet was washed by TEB.
  • the supernatant was removed and added 200 ⁇ L of 0.2 N HCl and rotate at 4°C for 2 hours.
  • the sample was centrifuged with max speed for 15 min and the supernatant was collected in another tube and neutralize with using 1 N NaOH. This sample was used to the immunochemical detection.
  • Test Example 6 Immunochemical detection of the level of Histone acetylation The concentration of protein in each supernatant obtained in Test Example 2 and Test Example 5 was determined by using the BCA kit (Thermo Fisher Science, Rockfield, IL). Equal amounts of samples (10 ⁇ g protein) were electropheretically separated in 10-20% gradient acrylamide gels (Wako, Japan) and then transferred to PVDF membranes.
  • the membranes were then blotted with a mouse monoclonal antibody against acetyl-H4(Lys12) (Merck KGaA, Darmstadt, Germany), a mouse monoclonal antibody against acetyl-H3(Lys9) (Merck KGaA, Darmstadt, Germany) or a mouse monoclonal antibody against actin (MILLIPORE, Billerica, MA).
  • MILLIPORE horse monoclonal antibody against actin
  • HRP-conjugated secondary antibodies (MILLIPORE, Billerica, MA) were used and detected by using ECL kit (Merck KGaA, Darmstadt, Germany).
  • the band intensity was measured with Image Analysis Software Quantity One (BIO-RAD, Hercules, CA). The statistical difference was assessed by Student’s t-test or Dunnett test.
  • H4K12 and H3K9 human neuroblastoma
  • Histone H4K12 acetylation levels were increased by the treatment of EX11 in mouse brain at 4 hours after 100 mg/kg dosing with statistical significance compared to the vehicle control (p ⁇ 0.05). The results demonstrate that EX11 has an HDAC2 inhibition activity as well as good brain penetration (Fig. 3).
  • a compound of Formula [I], or a pharmaceutically acceptable salt thereof has an HDAC inhibition activity, and is expected to be used as a medicament for treatment and/or prevention of diseases involving HDACs.

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Abstract

Pyrrolidine compounds having an HDAC inhibition activity which are useful for treatment or prevention of diseases involving HDACs are provided. A compound of Formula [I], or a salt thereof, wherein R1 is an optionally substituted 6- to 10-membered aryl, etc.; a ring structure A is any one of the formulae (A1) to (A3) wherein ring groups G1 and G2 are each independently 6- to 10-membered aryl or 5- to 10-membered heteroaryl, which is optionally substituted with oxo; m and n are each independently an integer of 1 or 2; R21, R22, and R23 are each independent, each of which is independent when existing plurally, and are an optionally C1-6 alkyl, etc.; and p, q, and r are each independently an integer of 0 to 2.

Description

PYRROLIDINE COMPOUNDS AS HISTONE DEACETYLASE INHIBITORS
The present invention is directed to novel pyrrolidine compounds or salts thereof, which are useful as an HDAC inhibitor, and medical use thereof.
Histone acetylation and deacetylation processes are essential for the regulation of chromatin unfolding and gene expression. Histone deacetylase (HDAC) enzymes play a key role in these post-translational modifications which makes them important therapeutic targets for a number of indications. The connection between these epigenetic targets and central nervous system (CNS) diseases such as neurodegeneration has been published by NPL 1. The level of histone deacetylase was found to be increased in the brain of mouse models of neurodegeneration and in patients with Alzheimer’s disease. In particular, HDAC2 among 18 known human histone deacetylases was found to be responsible for the reduction of histone acetylation (NPL 1).
HDAC2 inhibitors have a memory-enhancing effect and an action to improve memory impairment by increasing histone acetylation in the nucleus of nerve cells, thereby altering chromatin structure and altering the profile of gene expression (NPL 2, 3). These effect and action may connect to cognitive dysfunction in Alzheimer's disease (NPL 4), Parkinson's disease (NPL 5), Lewy body dementia (NPL 5), frontotemporal dementia, frontotemporal lobar dementia, and amyotrophic lateral sclerosis (NPL 6, 7).
In the in vitro / in vivo models of Rubinstein-Taybi syndrome with gene mutations in CBP and p300 proteins, which have the function of catalyzing histone acetylation in the cell nucleus, HDAC inhibitors normalize gene expression by enhancing histone acetylation (NPL 8).
Friedreich's ataxia, one of the spinocerebellar degenerations, is thought to be caused by a marked decrease in the expression level of the FXN gene, which encodes a protein called frataxin in mitochondria, in triplet repeat disease. HDAC inhibitors enhanced histone acetylation and improved FXN gene expression in stem cells from Friedreich's ataxia patients and model animals (NPL 9).
It has been reported that HDAC2 knockout mice and HDAC2 inhibitors activate nerve cells in the area around the infarction of cerebral infarction model animals and increase the plasticity of the nerves, thereby reducing the infarct lesion and restoring motor function after cerebral infarction or brain damage (NPL 10).
Oral administration of the class I HDAC inhibitor CI-994 to spinal cord injury model animals increases histone acetylation in the brain and ameliorates motor dysfunction. It has also been reported that it suppresses neuroinflammation by reducing neutrophils and inflammatory cytokines (NPL 11).
HDAC1/2/6/Sp1 is elevated in temozolomide-resistant brain tumors, which are used as the first-line treatment for high-grade astrocytoma brain tumors. It has also been reported that HDAC inhibitors cause cell senescence and induce apoptosis by rotating the cell cycle of temozolomide-resistant cancer cells (NPL 12). This suggests that brain-penetrant HDAC inhibitors can be effective against brain tumors such as glioma.
Accumulating evidence suggests that histone hypoacetylation is involved in development and maintenance of neuropathic pain. HDAC inhibitors exhibited a remarkable analgesic effect against neuropathic pain in animals. HDAC2 has been found to be involved in mechanical and thermal hyperalgesia induced by peripheral nerve injury (NPL 13).
Hereditary neuropathies are a group of inherited disorders affecting the peripheral nervous system. The hereditary neuropathies are divided into four major subcategories: hereditary motor and sensory neuropathy, hereditary sensory neuropathy, hereditary motor neuropathy, and hereditary sensory and autonomic neuropathy. The most common type is Charcot-Marie-Tooth disease, one of the hereditary motor and sensory neuropathies. Histone deacetylases plays a central role in various processes that are key for neuronal survival providing a rationale for the use of small-molecule HDAC inhibitors as a therapeutic strategy for hereditary neuropathy (NPL 14).
Deletion of HDAC2 in forebrain pyramidal neurons prevented the negative effects of antipsychotic treatment on synaptic remodeling and cognition. Conversely, virally mediated activation of NF-κB signaling decreased cortical synaptic plasticity via HDAC2. Together, these observations may aid in developing therapeutic strategies to improve the outcome of schizophrenia treatment (NPL 15).
It has been found that compounds that inhibit HDACs are effective in normalizing manic-like behavior, and that class I HDACs (e.g., HDAC1 and HDAC2) are most important in this response (NPL 16).
Abnormal expression of HDACs is often reported in various types of cancers. Isoform-selective HDAC inhibition can be one of the best therapeutic strategies in the treatment of cancer (NPL 17). HDAC2 is elevated in cancers such as gastric cancer, prostate cancer, colorectal cancer, Hodgkin lymphoma, and cutaneous T cell lymphoma. In addition, HDAC2 knockdown induces growth arrest, decreased viability, and increased apoptosis in colon and breast cancer cells and induced apoptosis and decreased lung cancer in animals (NPL 18). It was also reported that the rational design of selective HDAC2 inhibitors is beneficial for the therapeutic treatment of liver cancer (NPL 19).
Four HDAC pan-inhibitors have been approved by the FDA to date in cancer therapy: vorinostat, romidepsin, panobinostat and belinostat. Almost all of them share the same hydroxamate zinc binding group and their use may lead to side effects such as thrombocytopenia, neutropenia, diarrhea, nausea, vomiting and fatigue (NPL 20). This makes them unsuitable for the chronic dosing required to treat neurodegenerative disease. Other examples of clinical HDACi feature the α-aminobenzamide zinc binding group which are also associated with potential toxicity issues (NPL 21).
It is desirous to find out a novel HDAC inhibitor with good brain penetration and less side effects or toxicity which could be developed as a promising drug for treatment of diseases involving HDACs.
[PTL 1] WO 2017/136451 A1
[PTL 2] WO 2017/007756 A1
[NPL 1] Graeff, J. et al., Nature 2012, 483, 222-226.
[NPL 2] Graeff, J. et al., The potential of HDAC inhibitors as cognitive enhancers. Annual review of pharmacology and toxicology, Vol 53, 2013. Volume 53, Edited by Insel PA; 2013: 311-330
[NPL 3] Guan, S-J. et al., HDAC2 negatively regulates memory formation and synaptic plasticity. Nature. 2009, 459, 55-60.
[NPL 4] Sung, Y-M. et al., Mercaptoacetamide-based class II HDAC inhibitor lowers Abeta levels and improves learning and memory in a mouse model of Alzheimer's disease. Exp Neurol. 2013; 239: 192-201.
[NPL 5] Choong, C-J. et al., A novel histone deacetylase 1 and 2 isoform-specific inhibitor alleviates experimental Parkinson’s disease. Neurobiol Aging 2016; 37: 103-16.
[NPL 6] Simona Sanna, S. et al., HDAC1 inhibition ameliorates TDP-43-induced cell death in vitro and in vivo. Cell Death & Disease volume 11, Article number: 369 (2020).
[NPL 7] Rossaert, E. et al., Restoration of histone acetylation ameliorates disease and metabolic abnormalities in a FUS mouse model. Acta Neuropathologica Communications volume 7, Article number: 107 (2019).
[NPL 8] Fede, E. D. et al., Exogenous and endogenous HDAC inhibitor effects in Rubinstein-Taybi syndrome models. bioRxiv April 01 2020.
[NPL 9] Gottesfeld, J. M. et al., Increasing frataxin gene expression with histone deacetylase inhibitors as a therapeutic approach for friedreich's ataxia. J Neurochem. 2013 August; 126(0 1): 147-154.
[NPL 10] Tang, Y. et al., Inhibiting histone deacetylase 2 (HDAC2) promotes functional recovery from stroke. J Am Heart Assoc. 2017 Oct 5; 6(10).
[NPL 11] Zhang, S. et al., Class I histone deacetylase (HDAC) inhibitor CI-994 promotes functional recovery following spinal cord injury. Cell Death & Disease volume 9, Article number: 460 (2018).
[NPL 12] Yang, W-B. et al., Increased activation of HDAC1/2/6 and Sp1 underlies therapeutic resistance and tumor growth in glioblastoma. Neuro Oncol. 2020 Oct 14; 22(10):1439-1451.
[NPL 13] Ouyang, B. et al., Normalizing HDAC2 levels in the spinal cord alleviates thermal and mechanical hyperalgesia after peripheral nerve injury and promotes GAD65 and KCC2 expression. Frontiers in neuroscience (2019), 13, 346.
[NPL 14] Rossaert, E. et al., HDAC6 inhibitors: Translating genetic and molecular insights into a therapy for axonal CMT. Brain Research (2020), 1733, 146692.
[NPL 15] Ibi, D. et al., Antipsychotic-induced Hdac2 transcription via NF-kB leads to synaptic and cognitive side effects. Nature Neuroscience (2017), 20(9), 1247-1259.
[NPL 16] Logan, R. W. et al., Valproate reverses mania-like behaviors in mice via preferential targeting of HDAC2. Molecular Psychiatry, 2020 Nov 24.
[NPL 17] Shetty, M. G. et al., Histone deacetylase 2 selective inhibitors: A versatile therapeutic strategy as next generation drug target in cancer therapy. Pharmacological Research 2021, 170 105695-105707.
[NPL 18] West, A. C. et al., New and emerging HDAC inhibitors for cancer treatment. J Clin Invest. 2014; 124(1):30-39.
[NPL 19] Yang, Ye et al., Rational design of selective HDAC2 inhibitors for liver cancer treatment: computational insights into the selectivity mechanism through molecular dynamics simulations and QM/MM calculation. Physical Chemistry Chemical Physics 2021, 23, 17576-17590.
[NPL 20] Gryder, B. E. et al., Targeted Cancer Therapy: Giving Histone Deacetylase Inhibitors All They Need to Succeed. Future Med. Chem. 2012, 4, 505-524.
[NPL 21] Mottamal, M. et al., Histone Deacetylase Inhibitors in Clinical Studies as Templates for New Anticancer Agents. Molecules, 2015, 20, 3898-3941.
One of the problems to be solved by the present invention is to provide a novel drug for treatment or prevention of diseases involving HDACs.
The present inventors have achieved success in preparation of novel pyrrolidine compounds of the following Formula [I], or salts thereof, having an HDAC inhibitory activity and with good brain penetration, and found out that these compounds may be a new and promising drug for treatment and/or prevention of diseases involving HDACs. On the basis of these findings, the present invention has been accomplished.
One aspect of the present invention is a compound of Formula [I]:
Figure JPOXMLDOC01-appb-C000012
 or a salt thereof (wherein a compound of Formula [I] or a salt thereof is also referred to as "Compound [I]" hereinafter),
wherein R1 is
1) an optionally substituted 6- to 10-membered aryl,
2) an optionally substituted 5- to 10-membered heteroaryl, provided that when the heteroaryl is a tetrazolyl, the tetrazolyl should bind to the pyrrolidine ring via its carbon atom, or
3) -O-C4-10 alkyl;
a ring structure A of the following formula:
Figure JPOXMLDOC01-appb-C000013
 is any one of the following formulae (A1) to (A3):
Figure JPOXMLDOC01-appb-C000014
 wherein ring groups G1 and G2 of the following formulae:
Figure JPOXMLDOC01-appb-C000015
 are each independently 6- to 10-membered aryl or 5- to 10-membered heteroaryl, which is optionally substituted with oxo;
X1 is N, CH, or C;
the following structure:
Figure JPOXMLDOC01-appb-C000016
 in the formula (A1) is a bond, wherein:
1) when X1 is N, then the bond is a single bond,
2) when X1 is CH, then the bond is a single bond, and
3) when X1 is C, then the bond is a double bond;
m and n are each independently an integer of 1 or 2;
R21, R22, and R23 are each independent, each of which is independent when existing plurally, and are:
1) C1-6 alkyl, C2-6 alkenyl, C3-6 cycloalkyl, 6- to 10-membered aryl, 5- to 10-membered mono- or bi-cyclic heteroaryl, or -NH-C(=O)-C1-6 alkyl, wherein these groups are optionally substituted,
2) -OR24, wherein R24 is hydrogen or an optionally substituted C1-6 alkyl,
3) halogen, or
4) cyano;
p, q, and r are each independently an integer of 0 to 2; and
a wavy line is a binding site.
Compound [I] has a pyrrolidine structure with an α-carbonyl group, which could bind to a zinc binding site at an enzyme activity center via this structure, resulting in an HDAC inhibition activity. Compound [I] may be a novel and potent HDAC inhibitor with good brain penetration, and could be developed as a drug for treatment and/or prevention of diseases involving HDACs with less side effects than known HDAC inhibitors such as those having hydroxamic-acid or benzamide motifs (PTL 1, PTL 2).
Fig. 1 shows a graph of Histon H4K12 acetylation levels in SKNSH cells treated with increasing concentrations of EX 11. Fig. 2 shows a graph of Histon H3K9 acetylation levels in SKNSH cells treated with increasing concentrations of EX 11. Fig. 3 shows a graph of Histon H4K12 acetylation levels in mouse brain at different time points after PO dosing of EX 11 at 100 mg/kg.
The term "halogen" used herein includes fluorine, chlorine, bromine, and iodine atoms, preferably fluorine and chlorine atoms.
The term "alkyl" used herein refers to a straight or branched chain alkyl group having, e.g., 1 to 10 carbon atoms, i.e., C1-10 alkyl. Examples of alkyl include C1-6 alkyl and C4-10 alkyl, and specifically, include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl, isohexyl, 3-methylpentyl, 2-ethylbutyl, heptyl, octyl, nonyl, and decyl.
The term "haloalkyl" used herein refers to a straight or branched chain alkyl group substituted with the same or different 1 to 12 halogen atoms. Examples of haloalkyl include halo-C1-6 alkyl, and specifically, include monofluoromethyl, difluoromethyl, trifluoromethyl, 2-chloroethyl, 2-bromoethyl, 2,2-difluoroethyl, 2-chloro-2-fluoroethyl, 2,2,2-trifluoroethyl, 2,2,2-trifluoro-1-methylethyl, pentafluoroethyl, 2-trifluoromethylpropyl, and 4-fluorobutyl.
The term "alkenyl" used herein refers to a straight or branched chain alkenyl group having, e.g., 2 to 6 carbon atoms and 1 to 3 double bonds, i.e., C2-6 alkenyl, and specifically, includes vinyl (i.e., ethenyl), 1-propenyl, 2-propenyl, isopropenyl, 2-methyl-1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 3-methyl-2-butenyl, 1,3-butadienyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 4-methyl-3-pentenyl, 1-hexenyl, 3-hexenyl, and 5-hexenyl.
The term "alkynyl" used herein refers to a straight or branched chain alkynyl group having, e.g., 2 to 6 carbon atoms and 1 to 3 triple bonds, i.e., C2-6 alkynyl, and specifically, includes ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-methyl-2-propynyl, 1-ethylethynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 1-hexynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, 5-hexynyl, 3,4-dimethylbutynyl, and 4-methyl-2-pentynyl.
The term "cycloalkyl" used herein refers to a cyclic alkyl group having, e.g., 3 to 6 carbon atoms, i.e., C3-6 cycloalkyl, and specifically, includes cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.
The term "aryl" used herein includes 6- to 10-membered aryl. The term "6- to 10-membered aryl" used herein refers to a mono- or bi-cyclic aromatic hydrocarbon group having 6 to 10 carbon atoms, i.e., C6-10 aryl, and specifically, includes phenyl and naphthyl. C6-10 aryl is optionally substituted with an oxo group, so that the C6-10 aryl may lose the aromaticity to form a corresponding oxo-substituted carbocyclyl group.
The term "aralkyl" used herein refers to an arylalkyl group wherein the aryl and alkyl are defined as above.
The term "heteroaryl" used herein includes 5- to 10-membered heteroaryl. The term "5- to 10-membered heteroaryl" used herein refers to a mono- or bi-cyclic aromatic heterocyclyl group having 5 to 10 atoms comprising at least one heteroatom, e.g., 1 to 3 heteroatoms, independently selected from the group consisting of oxygen, nitrogen, and sulfur atoms, and specifically, includes furyl, pyrrolyl, thiophenyl, thiazolyl, pyrazolyl, imidazolyl, pyridyl, pyrazinyl, benzothiophenyl, thienopyridyl, thienopyrimidinyl, furopyridyl, quinolinyl, and isoquinolinyl. A 5- to 10-membered heteroaryl group is optionally substituted with an oxo group, so that the heteroaryl group may lose the aromaticity to form a corresponding oxo-substituted heterocyclyl group.
The term "heterocyclyl" used herein includes 5- to 10-membered heterocyclyl. The term "5- to 10-membered heterocyclyl" used herein refers to a mono- or bi-cyclic saturated or partially unsaturated heterocyclyl group having 5 to 10 atoms comprising at least one heteroatom, e.g., 1 to 3 heteroatoms, independently selected from the group consisting of oxygen, nitrogen, and sulfur atoms, and specifically, includes pyrrolidinyl, piperidinyl, piperazinyl, tetrahydrofuranyl, tetrahydropyranyl, dihydropyranyl, tetrahydropyridinyl, dihydropyridinyl, morpholinyl, azepanyl, indolinyl, isoindolinyl, dihydroquinolinyl, and tetrahydroquinolinyl.
Examples of a "substituent" in the term "optionally substituted α" wherein α refers to any one of groups described herein or in any one of groups having at least one substituent described herein include at least one group, e.g., 1 to 10, 1 to 8, 1 to 6, 1 to 5, 1 to 4, 1 to 3, or 1 to 2 groups, independently selected from the group consisting of:
(A) halogen,
(B) -CN,
(C) -NO2,
(D) =N-OH,
(E) -OH,
(F) -CHO,
(G) -COOH,
(H) -SO3H,
(I) -SO2H,
(J) -SH,
(K) =O,
(L) =S,
(M) alkyl optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(N) alkenyl optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(O) alkynyl optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(P) alkyl-O- optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(Q) alkenyl-O- optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(R) alkynyl-O- optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(S) alkyl-CO- optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(T) alkenyl-CO- optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(U) alkynyl-CO- optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(V) alkyl-COO- optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(W) alkyl-O-CO- optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(X) alkyl-S- optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(Y) alkyl-SO- optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(Z) alkyl-SO2- optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ib),
(AA) cycloalkyl optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), (Ic), and =O,
(BB) cycloalkyl-O- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), (Ic), and =O,
(CC) cycloalkenyl optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), (Ic), and =O,
(DD) cycloalkenyl-O- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), (Ic), and =O,
(EE) cycloalkyl-CO- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), (Ic), and =O,
(FF) cycloalkyl-O-CO- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), (Ic), and =O,
(GG) aryl optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), and (Ic),
(HH) aryl-O- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), and (Ic),
(II) aryl-CO- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), and (Ic),
(JJ) aryl-O-CO- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), and (Ic),
(KK) aralkyl optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), and (Ic),
(LL) aralkyl-O- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), and (Ic),
(MM) aralkyl-CO- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), and (Ic),
(NN) aralkyl-O-CO- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), and (Ic),
(OO) heterocyclyl group optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), (Ic), and =O,
(PP) heterocyclyl-O- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), (Ic), and =O,
(QQ) heterocyclyl-CO- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), (Ic), and =O,
(RR) heterocyclyl-O-CO- optionally substituted with at least one group independently selected from the substituent groups (Ia), (Ib), (Ic), and =O,
(SS) amino optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ic), and
(TT) carbamoyl optionally substituted with at least one group independently selected from the substituent groups (Ia) and (Ic).
The number of substituents of any one of groups in the compound of Formula [I] is not limited, unless otherwise specified, as long as it is chemically acceptable, and for example, includes 1 to 10, 1 to 8, 1 to 6, 1 to 4, and 1 to 3. When α is amino or carbamoyl, the number of substituents on α is 1 or 2. Substituents may bind to any atoms such as carbon atoms and heteroatoms as long as they are chemically acceptable.
The "substituent group (Ia)" is the group consisting of:
(a) alkyl-CO- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb),
(b) alkenyl-CO- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb),
(c) alkynyl-CO- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb),
(d) alkyl-O-CO- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb),
(e) alkyl-S- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb),
(f) alkyl-SO- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb),
(g) alkyl-SO2- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb),
(h) cycloalkyl that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), (IIc), and =O,
(i) cycloalkyl-O- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), (IIc), and =O,
(j) cycloalkenyl that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), (IIc), and =O,
(k) cycloalkyl-CO- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), (IIc), and =O,
(l) cycloalkyl-O-CO- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), (IIc), and =O,
(m) aryl that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), and (IIc),
(n) aryl-CO- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), and (IIc),
(o) aryl-O-CO- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), and (IIc),
(p) aralkyl that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), and (IIc),
(q) aralkyl-CO- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), and (IIc),
(r) aralkyl-O-CO- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), and (IIc),
(s) heterocyclyl group that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), (IIc), and =O,
(t) heterocyclyl-CO- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), (IIc), and =O,
(v) heterocyclyl-O-CO- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), (IIc), and =O, and
(w) carbamoyl that optionally has at least one group independently selected from the substituent groups (IIa) and (IIc).
The "substituent group (Ib)" is the group consisting of:
(a) halogen,
(b) -CN,
(c) -NO2,
(d) -OH,
(e) -CHO,
(f) -COOH,
(g) -SO3H,
(h) -SH,
(i) alkyl-O- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb),
(j) alkenyl-O- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb),
(k) alkynyl-O- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb),
(l) alkyl-COO- that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb),
(m) cycloalkenyl-O- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), (IIc), and =O,
(n) aryl-O- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), and (IIc),
(o) aralkyl-O- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), and (IIc),
(p) heterocyclyl-O- that optionally has at least one group independently selected from the substituent groups (IIa), (IIb), (IIc), and =O, and
(q) amino that optionally has at least one group independently selected from the substituent groups (IIa) and (IIc).
The "substituent group (Ic)" is the group consisting of:
(a) alkyl that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb),
(b) alkenyl that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb), and
(c) alkynyl that optionally has at least one group independently selected from the substituent groups (IIa) and (IIb).
The "substituent group (IIa)" is the group consisting of -CHO, alkyl-CO-, alkenyl-CO-, alkynyl-CO-, alkyl-O-CO-, alkyl-SO2-, cycloalkyl, cycloalkyl-O-, cycloalkenyl, cycloalkyl-CO-, cycloalkyl-O-CO-, aryl, aryl-CO-, aryl-O-CO-, aralkyl, aralkyl-CO-, aralkyl-O-CO-, heterocycle, heterocyclyl-CO-, heterocyclyl-O-CO-, mono- or di-(alkyl-CO)-carbamoyl, and mono- or di-alkylcarbamoyl.
The "substituent group (IIb)" is the group consisting of halogen, -CN, -NO2, -OH, -COOH, -SO3H, -SH, -NH2, alkyl-O-, alkenyl-O-, alkynyl-O-, alkyl-COO-, alkyl-S-, alkyl-SO-, cycloalkenyl-O-, aryl-O-, aralkyl-O-, heterocyclyl-O-, mono- or di-alkylamino, mono- or di-(alkyl-CO)-amino, mono- or di-alkyl-O-carbonylamino, mono- or di-arylcarbonylamino, and mono- or di-aralkylcarbonylamino.
The "substituent group (IIc)" is the group consisting of alkyl, alkenyl, and alkynyl.
Specific embodiments of the present invention are illustrated as follows.
Item 1.
A compound of Formula [I]:
Figure JPOXMLDOC01-appb-C000017
 or a salt thereof,
wherein R1 is
1) an optionally substituted 6- to 10-membered aryl,
2) an optionally substituted 5- to 10-membered heteroaryl, provided that when the heteroaryl is a tetrazolyl, the tetrazolyl should bind to the pyrrolidine ring via its carbon atom, or
3) -O-C4-10 alkyl;
a ring structure A of the following formula:
Figure JPOXMLDOC01-appb-C000018
 is any one of the following formulae (A1) to (A3):
Figure JPOXMLDOC01-appb-C000019
 wherein ring groups G1 and G2 of the following formulae:
Figure JPOXMLDOC01-appb-C000020
 are each independently 6- to 10-membered aryl or 5- to 10-membered heteroaryl, which is optionally substituted with oxo;
X1 is N, CH, or C;
the following structure:
Figure JPOXMLDOC01-appb-C000021
 in the formula (A1) is a bond, wherein:
1) when X1 is N, then the bond is a single bond,
2) when X1 is CH, then the bond is a single bond, and
3) when X1 is C, then the bond is a double bond;
m and n are each independently an integer of 1 or 2;
R21, R22, and R23 are each independent, each of which is independent when existing plurally, and are:
1) C1-6 alkyl, C2-6 alkenyl, C3-6 cycloalkyl, 6- to 10-membered aryl, 5- to 10-membered mono- or bi-cyclic heteroaryl, or -NH-C(=O)-C1-6 alkyl, wherein these groups are optionally substituted,
2) -OR24, wherein R24 is hydrogen or an optionally substituted C1-6 alkyl,
3) halogen, or
4) cyano;
p, q, and r are each independently an integer of 0 to 2; and
a wavy line is a binding site.
Item 2.
The compound according to Item 1, or a salt thereof, wherein R1 is:
1) 6- to 10-membered aryl or 5- to 10-membered heteroaryl, which is optionally substituted with 1 to 3 groups independently selected from the group consisting of the following groups 1-1) to 1-8):
1-1) C1-6 alkyl,
1-2) halo-C1-6 alkyl,
1-3) C3-6 cycloalkyl,
1-4) -OR11, wherein R11 is hydrogen or C1-6 alkyl,
1-5) -NH-C(=O)-C1-6 alkyl,
1-6) -C(=O)-NH-C1-6 alkyl,
1-7) halogen, and
1-8) 5- to 10-membered heterocyclyl optionally substituted with oxo, or
2) -O-C4-10 alkyl.
Item 3.
The compound of according to Item 1 or 2, or a salt thereof, wherein ring groups G1 and G2 are each independently any one of the following ring groups:
Figure JPOXMLDOC01-appb-C000022
 wherein X21, X22, X31, X32, X41, X42, and X51 are each independently N or CH, and
X61 is NH or O.
Item 4.
The compound according to any one of Items 1 to 3, or a salt thereof, wherein ring groups G1 and G2 are each independently any one of the following ring groups.
Figure JPOXMLDOC01-appb-C000023
Item 5.
The compound according to any one of Items 1 to 4, or a salt thereof, wherein R21, R22, and R23 are each independent, each of which is independent when existing plurally, and are:
1) C1-6 alkyl, C2-6 alkenyl, C3-6 cycloalkyl, 6- to 10-membered aryl, 5- to 10-membered mono- or bi-cyclic heteroaryl, or -NH-C(=O)-C1-6 alkyl,
2) -OR24, wherein R24 is hydrogen or C1-6 alkyl,
3) halogen, or
4) cyano; wherein
each group in the above group 1) and the C1-6 alkyl in the above group 2) may be optionally substituted with 1 to 3 substituents independently selected from the group consisting of the following groups 2-1) to 2-7):
2-1) halogen,
2-2) cyano,
2-3) -O-C1-6 alkyl,
2-4) an optionally substituted 5- to 10-membered heteroaryl,
2-5) an optionally substituted 6- to 10-membered aryl,
2-6) an optionally substituted -C(=O)-NH-(6- to 10-membered aryl), and
2-7) an optionally substituted -NH-(6- to 10-membered aryl).
Item 6.
The compound according to any one of Items 1 to 5, or a salt thereof, wherein R21, R22, and R23 are each independent, each of which is independent when existing plurally, and are:
1) C1-6 alkyl optionally substituted with 1 to 3 substituents independently selected from the group consisting of halogen, an optionally substituted 5- to 10-membered heteroaryl, an optionally substituted 6- to 10-membered aryl, an optionally substituted -C(=O)-NH-(6- to 10-membered aryl), and an optionally substituted -NH-(6- to 10-membered aryl),
2) C2-6 alkenyl,
3) C3-6 cycloalkyl,
4) -O-C1-6 alkyl,
5) 6- to 10-membered aryl optionally substituted with 1 to 3 substituents independently selected from the group consisting of halogen and cyano,
6) 5- to 10-membered mono- or bi-cyclic heteroaryl optionally substituted with 1 or 2 substituents independently selected from the group consisting of cyano and -O-C1-6 alkyl,
7) -NH-C(=O)-C1-6 alkyl optionally substituted with an optionally substituted 6- to 10-membered aryl or an optionally substituted 5- to 10-membered heteroaryl,
8) hydroxy,
9) halogen, or
10) cyano.
Item 7.
The compound according to Item 1, or a salt thereof, selected from the group consisting of the following compounds:
Figure JPOXMLDOC01-appb-C000024
Figure JPOXMLDOC01-appb-C000025
Item 8.
The compound according to Item 1, selected from the group consisting of the following compounds or salts:
Figure JPOXMLDOC01-appb-C000026
Figure JPOXMLDOC01-appb-C000027
Item 9.
A pharmaceutical composition comprising a compound according to any one of Items 1 to 8, or a salt thereof, and a pharmaceutically acceptable carrier.
Item 10.
The composition according to Item 9, for use in treatment or prevention of a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
Item 11.
A medicament for use in treatment or prevention of a disease involving HDAC, comprising a compound according to any one of Items 1 to 8, or a salt thereof.
Item 12.
A medicament for use in treatment or prevention of a disease involving HDAC2, comprising a compound according to any one of Items 1 to 8, or a salt thereof.
Item 13.
The medicament according to Item 11 or 12, wherein the disease is selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
Item 14.
A compound according to any one of Items 1 to 8, or a salt thereof, for use in treatment or prevention of a disease involving HDAC.
Item 15.
A compound according to any one of Items 1 to 8, or a salt thereof, for use in treatment or prevention of a disease involving HDAC2.
Item 16.
A compound according to any one of Items 1 to 8, or a salt thereof, for use in treatment or prevention of a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
Item 17.
Use of a compound according to any one of Items 1 to 8, or a salt thereof, or a pharmaceutical composition according to Item 9 in the manufacture of a medicament for use in treatment or prevention of a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
Item 18.
A method of treating or preventing a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy in a subject in need thereof, comprising administering a therapeutically effective amount of a compound according to any one of Items 1 to 8, or a salt thereof, or a pharmaceutical composition according to Item 9 to the subject.
In certain embodiments, R1 is:
1) C6-10 aryl, e.g., phenyl and naphthyl, optionally substituted with 1 to 3 groups independently selected from the group consisting of the following groups 1-1) to 1-7):
1-1) C1-6 alkyl,
1-2) halo-C1-6 alkyl,
1-3) C3-6 cycloalkyl,
1-4) -O-C1-6 alkyl,
1-5) -NH-C(=O)-C1-6 alkyl,
1-6) halogen, and
1-7) 5- to 10-membered nitrogen-containing heterocyclyl optionally substituted with oxo;
2) 5- to 10-membered mono- or bi-cyclic heteroaryl comprising at least one nitrogen atom, optionally substituted with 1 to 3 groups independently selected from the group consisting of the following groups 2-1) to 2-6):
2-1) C1-6 alkyl,
2-2) halo-C1-6 alkyl,
2-3) C3-6 cycloalkyl,
2-4) -O-C1-6 alkyl,
2-5) -NH-C(=O)-C1-6 alkyl, and
2-6) halogen; or
3) -O-C4-10 alkyl.
In certain embodiments, a ring structure A of the following formula:
Figure JPOXMLDOC01-appb-C000028
 is any one of the following formulae:
Figure JPOXMLDOC01-appb-C000029
 wherein G1, G2, R21, R22, R23, p, q, and r are the same as defined above.
In certain embodiments, R21, R22, and R23 are each independent, each of which is independent when existing plurally, and are:
1) C1-6 alkyl optionally substituted with 1 to 3 substituents independently selected from the group consisting of halogen, 5- to 10-membered nitrogen-containing heteroaryl, -C(=O)-NH-phenyl, and -NH-phenyl optionally substituted with halogen,
2) -O-C1-6 alkyl,
3) phenyl optionally substituted with 1 to 3 substituents independently selected from the group consisting of halogen and cyano,
4) 5- to 10-membered mono- or bi-cyclic heteroaryl optionally substituted with 1 or 2 substituent independently selected from the group consisting of cyano and -O-C1-6 alkyl,
5) -NH-C(=O)-C1-6 alkyl optionally substituted with phenyl optionally substituted with -O-C1-6 alkyl,
6) hydroxy,
7) halogen, or
8) cyano.
In certain embodiments, m is preferably 1.
In certain embodiments, n is preferably 1.
In certain embodiments, p is preferably 0 or 1.
In certain embodiments, q is preferably 0 or 1.
Specific or preferable embodiments or options in respect of different elements of Compound [I], methods, use, and compositions in the present invention include any combinations of these specific or preferable embodiments or options for different elements, insofar as they are combinable and compatible.
General Preparation
Methods of preparing Compound [I] are illustrated as below. The reagents and the reaction conditions used herein are not limited to those described herein, and may be selected from those used in the methods or examples described herein and any equivalents thereof. The methods described below are examples, and the methods for preparing Compound [I] are not limited thereto.
In the reaction schemes below, when performing an alkylation reaction, hydrogenation reaction, hydrolysis reaction, amination reaction, esterification reaction, amidation reaction etherification reaction, sulfonylation reaction, borylation reaction, de-benzylation reaction, nucleophilic substitution reaction, condensation reaction, coupling reaction, ring closure reaction, addition reaction, oxidation reaction, reduction reaction, protection and deprotection reactions, or the like, these reactions are themselves performed by known methods. Examples of such methods include the methods described in Experimental Chemistry (Fifth Edition, edited by The Chemical Society of Japan, Maruzen Co., Ltd.); Organic Functional Group Preparations Second Edition, Academic Press, Inc., 1989; Comprehensive Organic Transformations, VCH Publishers, Inc., 1989; and P.G.M. Wuts and T.W. Greene, Greene's Protective Groups in Organic Synthesis (Fourth Edition, 2006) and the like.
Inert solvents used herein include, for example, hydrocarbons, halogenated hydrocarbons, alcohols, ethers, esters, ketones, amides, nitriles, sulfoxides, and water, which may be used in combination with any two or more of these solvents with optional ratios.
Examples of "hydrocarbons" herein include, for example, aliphatic hydrocarbons such as hexane and pentane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; and aromatic hydrocarbons such as benzene and toluene.
Examples of "halogenated hydrocarbons" herein include, for example, chloroform and dichloromethane.
Examples of "alcohols" herein include, for example, methanol, ethanol, 2-propanol, propanol, and tert-butanol.
Examples of "ethers" herein include, for example, chained ethers such as diethyl ether, diisopropyl ether, dibutyl ether, and diphenyl ether; and circular ethers such as 1,4-dioxane and tetrahydrofuran.
Examples of "esters" herein include, for example, ethyl acetate and ethyl propionate.
Examples of "ketones" herein include, for example, acetone, methyl ethyl ketone, and methyl isobutyl ketone.
Examples of "amides" herein include, for example, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone.
Examples of "nitriles" herein include, for example, acetonitrile and propionitrile.
Examples of "sulfoxides" herein include, for example, dimethyl sulfoxide.
Bases used herein include, for example, alkali metal hydroxides, alkali metal hydrides, alkali metal carboxylates, alkali metal carbonates, alkali metal hydrogencarbonates, alkali metal phosphates, aromatic amines, tertiary amines, metal amides, and metal alkoxides.
Examples of "alkali metal hydroxides" herein include, for example, sodium hydroxide, potassium hydroxide, and cesium hydroxide.
Examples of "alkali metal hydrides" herein include, for example, sodium hydride, potassium hydride, and cesium hydride.
Examples of "alkali metal carboxylates" herein include, for example, sodium acetate, potassium acetate, and sodium butyrate.
Examples of "alkali metal carbonates" herein include, for example, sodium carbonate, potassium carbonate, cesium carbonate, and lithium carbonate.
Examples of "alkali metal hydrogencarbonates" herein include, for example, sodium hydrogencarbonate, potassium hydrogencarbonate, and cesium hydrogencarbonate.
Examples of "alkali metal phosphates" herein include, for example, sodium phosphate and potassium phosphate.
Examples of "aromatic amines" herein include, for example, pyridine and lutidine.
Examples of "tertiary amines" herein include, for example, triethylamine, tripropylamine, tributylamine, diisopropylethylamine, cyclohexyldimethylamine, 4-dimethylaminopyridine, N,N-dimethylaniline, N-methylpiperidine, N-methylpyrrolidine, N-methylmorpholine, tetramethylethylenediamine, tetramethylpropylenediamine, and 1,8-diazabicyclo[5,4,0]undec-7-ene (diazabicycloundecene).
Examples of "metal amides" herein include, for example, lithium diisopropylamide and lithium hexamethyldisilazide.
Examples of "metal alkoxides" herein include, for example, sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium tert-butoxide, and sodium phenoxide.
Acids used herein include, for example, inorganic acids and organic acids.
Examples of "inorganic acids" herein include, for example, hydrochloric acid, sulfuric acid, nitric acid, hydrobromic acid, and phosphoric acid.
Examples of "organic acids" herein include, for example, acetic acid, trifluoroacetic acid, oxalic acid, phthalic acid, fumaric acid, tartaric acid, maleic acid, citric acid, succinic acid, methanesulfonic acid, p-toluenesulfonic acid, and 10-camphorsulfonic acid.
Examples of a condensation agent used herein include, for example,
T3P; HATU; DCC; N-cyclohexyl-N’-morpholinoethylcarbodiimide; N-cyclohexyl-N’-(4-diethylaminocyclohexyl)carbodiimide; N,N’-diethylcarbodiimide; N,N’-diisopropylcarbodiimide; N,N-diisopropylethylamine; WSC or a hydrochloride salt thereof; N,N’-carbonylbis(2-methylimidazole); pentamethyleneketene-N-cyclohexylimine; diphenylketene-N-cyclohexylimine; ethoxyacetylene, 1-alkoxy-1-chloroethylene; trialkyl phosphite; ethyl polyphosphate; isopropyl polyphosphate; phosphoryl chloride; phosphorus trichloride; diphenylphosphoryl azide; thionyl chloride; oxalyl chloride; alkyl haloformate such as ethyl chloroformate and isopropyl chloroformate; triphenylphosphine; 2-ethyl-7-hydroxybenzisoxazolium salt; 2-ethyl-5-(m-sulfophenyl)isoxazolium hydroxide inner salt; benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate; 1-(p-chlorobenzenesulfonyloxy)-6-chloro-1H-benzotriazole; and so-called Vilsmeier agents prepared by reactions of DMF with thionyl chloride, phosgene, trichloromethyl chloroformate, or phosphorus oxychloride.
In addition to a condensation agent, a condensation accelerator may be added. Examples of a condensation accelerator used herein include, for example, 1-hydroxybenzotriazole (HOBt), N-hydroxysuccinimide (HOSu), 1-hydroxy-7-azabenzotriazole (HOAt), and hydroxy-3,4-dihydro-4-oxo-1,2,3-benzotriazine (HOOBt).
Examples of a "protecting group of hydroxy" used herein include, but not limited to, any protecting groups of hydroxy used in the field of synthetic organic chemistry, and include, for example, alkyl groups (e.g., methyl, ethyl, isopropyl, tert-butyl, trifluoromethyl, hydroxymethyl, 2-hydroxyethyl, acetylmethyl); alkenyl groups (e.g., ethenyl, 1-propenyl, 2-propenyl, 1-methyl-2-propenyl); alkynyl groups (e.g., ethynyl, 1-propynyl, 2-propynyl, 1-methyl-2-propynyl); formyl; alkyl (alkenyl) carbonyl groups (e.g., acetyl, propionyl, butyryl, isobutyryl, pentanoyl, pivaloyl, valeryl, isovaleryl, chloroacetyl, dichloroacetyl, trichloroacetyl, trifluoroacetyl, methoxyacetyl, acryloyl, propioloyl, methacryloyl, crotonoyl, isocrotonoyl, (E)-2-methyl-2-butenoyl); arylcarbonyl groups (e.g., benzoyl, α-naphthoyl, β-naphthoyl, 2-bromobenzoyl, 4-chlorobenzoyl, 2,4,6-trimethylbenzoyl, 4-toluoyl, 4-anisoyl, 4-nitrobenzoyl, 2-nitrobenzoyl, 2-(methoxycarbonyl)benzoyl, 4-phenylbenzoyl); alkoxycarbonyl groups (e.g., methoxycarbonyl, tert-butoxycarbonyl, 2,2,2-trichloroethoxycarbonyl, 2-trimethylsilylethoxycarbonyl, 9-fluorenylmethyloxycarbonyl); tetrahydro (thio) pyranyl (furanyl) groups (e.g., tetrahydropyran-2-yl, 3-bromotetrahydropyran-2-yl, 4-methoxytetrahydropyran-4-yl, tetrahydrothiopyran-2-yl, 4-methoxytetrahydrothiopyran-4-yl, tetrahydrofuran-2-yl, tetrahydrothiofuran-2-yl); silyl groups (e.g., trimethylsilyl, triethylsilyl, isopropyl dimethylsilyl, tert-butyldimethyl silyl, methyldiisopropyl silyl, methyl di-tert-butylsilyl, triisopropylsilyl, diphenylmethyl silyl, diphenylbutyl silyl, diphenylisopropyl silyl, phenyldiisopropyl silyl); alkoxymethyl groups (e.g., methoxymethyl, 1,1-dimethyl-1-methoxymethyl, ethoxymethyl, propoxymethyl, isopropoxymethyl, butoxymethyl, tert-butoxymethyl, 2-methoxyethoxymethyl, 2,2,2-trichloroethoxymethyl, bis(2-chloroethoxy)methyl); alkoxyethyl groups (e.g., 1-ethoxyethyl, 1-(isopropoxy)ethyl); halogenated ethyl groups (e.g., 2,2,2-trichloroethyl); aralkyl groups (e.g., benzyl, α-naphthylmethyl, β-naphthylmethyl, diphenylmethyl, triphenylmethyl, α-naphthyldiphenylmethyl, 9-anthrylmethyl, 4-methylbenzyl, 2,4,6-trimethylbenzyl, 3,4,5-trimethylbenzyl, 4-methoxybenzyl, 4-methoxyphenyldiphenylmethyl, 2-nitrobenzyl, 4-nitrobenzyl, 4-chlorobenzyl, 4-bromobenzyl, 4-cyanobenzyl); alkenyloxycarbonyl groups (e.g., vinyloxycarbonyl, allyloxycarbonyl); and aralkyloxycarbonyl groups (e.g., benzyloxycarbonyl, 4-methoxybenzyloxycarbonyl, 3,4-dimethoxybenzyloxycarbonyl, 2-nitrobenzyloxycarbonyl, 4-nitrobenzyloxycarbonyl).
Examples of a "protecting group of carboxy" used herein include, but not limited to, any protecting groups of carboxy used in the field of synthetic organic chemistry, and include, for example, the "alkyl groups", "alkenyl groups", "alkynyl groups", "aralkyl groups", and "silyl groups" as above listed in the examples of the "protecting group of hydroxy" and similar groups thereof.
Examples of a "protecting group of amino" used herein include, but not limited to, any protecting groups of amino used in the field of synthetic organic chemistry, and include, for example, the "alkyl (alkenyl) carbonyl groups", "arylcarbonyl groups", "alkoxycarbonyl groups", "silyl groups", "aralkyl groups", "alkenyloxycarbonyl groups", and "aralkyloxycarbonyl groups" as above listed in the "protecting group of hydroxy" and similar groups thereof.
Examples of a "protecting group of terminal acetylene" used herein include, but not limited to, any protecting groups of terminal acetylene used in the field of synthetic organic chemistry, and include, for example, the "silyl groups" as above listed in the "protecting group of hydroxy" and similar groups thereof.
Examples of a "leaving group" used herein include, for example, halogen (e.g., fluorine, chlorine, bromine, iodine), alkylsulfonyloxy groups (e.g., methylsulfonyloxy, ethylsulfonyloxy, trifluoromethylsulfonyloxy), and arylsulfonyloxy groups (e.g., benzenesulfonyloxy, p-toluenesulfonyloxy, 2,4,6-trimethylbenzenesulfonyloxy, 2-nitrobenzenesulfonyloxy, 4-nitrobenzenesulfonyloxy).
The reaction temperature in each step in the General Preparation typically ranges from -80 to 150°C. The reaction time in each step typically ranges from 0.1 to 200 hours.
Scheme 1
Figure JPOXMLDOC01-appb-C000030
 In the scheme, R1a is hydroxy, an optionally substituted 6- to 10-membered aryl, an optionally substituted 5- to 10-membered heteroaryl, or -O-C4-10 alkyl; R1 and A are the same as defined above; and PG1 is a protecting group of amino group as defined above.
Compound [I] may be prepared by coupling compound (1) and compound (2) in an inert solvent in the presence or absence of a base or acid, followed by deprotection of the PG1 group.
In one embodiment, Compound (1) and Compound (2) may be reacted under an amidation condition, followed by deprotection of the PG1 group to give Compound [I]. When R1a is hydroxy, an alkylation step may be comprised further to convert the hydroxy group into a corresponding -O-alkyl group.
The amidation step herein may be conducted by methods commonly used in the art, and for example, Compound (1) and Compound (2) may be subjected to dehydration condensation in an inert solvent in the presence of a condensation agent and a base in the presence or absence of a condensation accelerator.
The deprotection step herein may be conducted by methods commonly used in the art, and for example, the compound prepared in the amidation step may be deprotected in an inert solvent or without any solvent in the presence of an acid (e.g., hydrochloric acid and trifluoroacetic acid), when PG1 is tert-butoxycarbonyl (Boc) group.
The alkylation step herein may be conducted by methods commonly used in the art, and for example, the compound after the deprotection step may be reacted with alkyl-LG in an inert solvent in the presence of a base, where LG is a leaving group, when R1a is hydroxy.
In another embodiment, when Compound [I] has an isoindoline-carbonyl group, Compound [I] may be prepared by, for example, the following scheme.
Scheme 2
Figure JPOXMLDOC01-appb-C000031
 In the scheme, Ar is an optionally substituted 6- to 10-membered aryl or an optionally substituted 5- to 10-membered heteroaryl; B(OR')2 is B(OH)2 or B(O-alkyl)2 wherein two O-alkyl groups may be optionally combined together with boron so that B(O-alkyl)2 may form, for example, Bpin; and s is 0 to 2.
The amidation and deprotection steps herein may be conducted in a similar manner described in the above.
The trifluoromethanesulfonylation step may be conducted by methods commonly used in the art, and for example, the ketone compound may be reacted in the presence of N-phenyl-bis(trifluoromethanesulfonimide) in an inert solvent in the presence of a base.
The coupling step may be conducted by methods commonly used in the art, and for example, the compound having the trifluoromethanesulfonyloxy group may be subjected to the Suzuki Cross-coupling Reaction with boronic acid or boronic ester in the presence of a palladium compound such as Pd(0) including Pd(PPh3)4 and Pd/C and a ligand such as a phosphine ligand including Sphos and Xphos in an inert solvent in the presence of a base.
The hydrogenation step may be conducted by methods commonly used in the art, and for example, may be conducted in the presence of a hydrogen source, for example, hydrogen gas and a metal catalyst, for example, palladuim on carbon (Pd/C) and platinum oxide (PtO2).
Compound (1) may be commercially available or prepared by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below. For example, Compound (1) may be prepared by the following scheme.
Scheme 3
Figure JPOXMLDOC01-appb-C000032
 In the scheme, B(OR')2 and R1a are the same as defined above.
Step 1.
Compound (1-1) may be subjected to the Suzuki Cross-coupling Reaction with R1aB(OR')2 in the presence of a palladium catalyst and a ligand in an inert solvent in the presence of a base to give Compound (1-2).
Step 2.
Compound (1-2) may be hydrogenated in the presence of a palladium catalyst, e.g., Pd/C, to give Compound (1-3).
Step 3.
Compound (1-3) may be hydrolyzed to give Compound (1).
Solvents and other reagents, if any, and reaction conditions used in these steps may be selected from those described in the above.
In one embodiment, when R1a is a halogenated phenyl group, Compound (1) may be prepared by, for example, the following scheme.
Scheme 4
Figure JPOXMLDOC01-appb-C000033
 In the scheme, B(OR')2 is the same as defined above.
Each step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Compound (2) may be commercially available or prepared by methods commonly used in the art or by one or any combinations of the following illustrative schemes.
Scheme 5
Figure JPOXMLDOC01-appb-C000034
 [In the scheme, R2a is each independently selected from:
1) C1-6 alkyl, C2-6 alkenyl, C3-6 cycloalkyl, 6- to 10-membered aryl, 5- to 10-membered mono- or bi-cyclic heteroaryl, or -NH-C(=O)-C1-6 alkyl, wherein these groups are optionally substituted,
2) -OR24, wherein R24 is hydrogen or an optionally substituted C1-6 alkyl,
3) halogen, and
4) cyano;
Y is N or CH; B(OR'')2 is B(OH)2 or B(O-alkyl)2 wherein two O-alkyl groups are optionally combined together with boron so that B(O-alkyl)2 may form, for example, Bpin; and t is 0 to 2.]
Each step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Scheme 6
Figure JPOXMLDOC01-appb-C000035
 This step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Scheme 7
Figure JPOXMLDOC01-appb-C000036
 Each step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Scheme 8
Figure JPOXMLDOC01-appb-C000037
 Each step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Scheme 9
Figure JPOXMLDOC01-appb-C000038
 Each step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Scheme 10
Figure JPOXMLDOC01-appb-C000039
 Each step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Scheme 11
Figure JPOXMLDOC01-appb-C000040
 Each step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Scheme 12
Figure JPOXMLDOC01-appb-C000041
 Each step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Scheme 13
Figure JPOXMLDOC01-appb-C000042
 In the scheme, X is halogen; Ar is an optionally substituted C6-10 aryl; and u is 0 to 2.
Each step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Scheme 14
Figure JPOXMLDOC01-appb-C000043
 Each step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Scheme 15
Figure JPOXMLDOC01-appb-C000044
 Each step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Scheme 16
Figure JPOXMLDOC01-appb-C000045
 In the scheme, Y is the same as defined above.
This step can be conducted by methods commonly used in the art or in accordance with the methods described in Reference Examples or Examples described below.
Compound [I] can be prepared by any of the above schemes or processes, any analogous or equivalent methods thereof, or any combinations thereof. Compound [I] may also be prepared, if necessary, with modifications of the preparations, types, numbers, and/or positions of substituents in the starting materials and/or intermediates, or the reaction conditions herein, in view of commonly known methods. Compound [I] includes derivatives of Compound [I] which can be prepared by any known reactions such as alkylation, acylation, amidation, esterification, etherification, halogenation, hydroxylation, amination, aryl coupling, condensation including carbon extension reaction, addition, substitution, oxidation, reduction, dehydration, and hydrolysis.
Unless production methods are specified, starting materials used herein may be commercially available, or may be produced by known methods or analogous methods thereof.
Any functional groups of starting materials and intermediates in the above respective steps may be protected with appropriate protective groups before a particular reaction, and the protective groups may be deprotected after the particular reaction, if necessary, using any known methods (e.g., methods described in P. G. M. Wuts and T. W. Greene, "Greene's Protective Groups in Organic Synthesis" (4th ed., 2006)).
Any intermediates and final products in the above respective steps may be directly used in subsequent steps, or may be isolated and purified after completion of reactions. For example, these compounds may be isolated and purified by cooling reaction mixtures, followed by isolation procedures such as filtration, concentration, and extraction, to isolate crude reaction products, which are then subject to general purification procedures such as column chromatography and recrystallization.
Any starting materials, intermediates, and final products in the above respective steps as well as Compound [I] encompass corresponding compounds in the form of a solvate, such as a hydrate and ethanolate. Compound [I] may form a solvate thereof which is also encompassed by the present invention.
Any starting materials, intermediates, and final products as well as Compound [I] encompass corresponding geometric isomers, stereoisomers, optical isomers, and tautomers. These various isomers can be separated by any known separation methods. For example, a racemic compound can be separated to a sterically pure isomer by common optical resolution (e.g., optical resolution by crystallization and direct optical resolution by chromatography). An optically active compound can also be prepared with an appropriate optically active starting material. Any prepared compounds may be isolated as chemically stable tautomers thereof.
When a compound obtained in each step or a commercially available product is in a free form, it can be converted to a corresponding desired salt by a known method per se. When a compound obtained in each step or a commercially available product is in a salt form, it can be converted to a corresponding free form or another desired salt form by a known method per se.
Compound [I] includes a pharmaceutically acceptable salt form thereof. The salt used herein includes salts with any commonly used pharmaceutically acceptable acids, bases, and amino acids. Examples of the acids include inorganic acids such as hydrochloric acid, hydrobromic acid, nitric acid, sulfuric acid, and phosphoric acid; and organic acids such as methanesulfonic acid, p-toluenesulfonic acid, acetic acid, citric acid, tartaric acid, maleic acid, fumaric acid, malic acid, and lactic acid. Examples of the bases include inorganic bases such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, and potassium hydrogencarbonate; organic bases such as methylamine, diethylamine, trimethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, ethylenediamine, tris(hydroxymethyl)methylamine, dicyclohexylamine, N,N'-dibenzylethylenediamine, guanidine, pyridine, picoline, and choline; and ammonium salts. Examples of the amino acids include lysine, arginine, asparagine acid, and glutamic acid.
Compound [I] includes any compounds wherein one or more atoms are replaced with one or more isotopic atoms. Examples of the isotopic atoms include deuterium (2H, D), tritium (3H), 13C, 14N, and 18O.
Compound [I] also includes a prodrug form thereof. The "prodrug" refers to any compounds that are chemically or metabolically converted into Compound [I] as the active metabolite under physiological conditions after administration in vivo, and includes those which a part of substituents of Compound [I] is chemically modified. Prodrugs may be utilized for several purposes including enhancement of water solubility, improvement of bioavailability and/or stability, reduction of side effects, adjusted metabolism, sustained efficacy, and drug selectivity against target sites. Substituents for modification to form a prodrug include any reactive functional groups such as -OH, -COOH, and amino. Such modifications of functional groups may be optionally selected from the "substituents" used herein.
Compound [I] may be in the form of a pharmaceutically acceptable co-crystal or co-crystal salt. Co-crystals and co-crystal salts can be manufactured appropriately by well-known co-crystallization methods.
Compound [I] may be useful for an HDAC inhibitor with good brain penetration, and may be a new and promising drug for treatment or prevention of diseases involving HDACs, e.g., Class I HDACs such as HDAC2. Histone acetylation plays an important role in CNS functions such as neuronal differentiation, memory formation, drug addiction, and depression. In one aspect, Compound [I] may be useful in treating neurological disorders. Neurological disorders include chronic or acute diseases, and familial or sporadic diseases. Examples of diseases involving HDACs herein include central nervous system diseases including neurological and/or neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson disease (PD), Lewy body dementia, frontotemporal dementia (FTD), frontotemporal lobar dementia, and amyotrophic lateral sclerosis (ALS, also known as motor neurone disease (MND) or Lou Gehrig’s disease), cognitive dysfunction, Rubinstein-Taybi syndrome, and spinocerebellar degeneration such as Friedreich's ataxia; psychiatric diseases such as schizophrenia, mania, depression, and memory loss; acute and chronic cerebral infarction and brain damage; acute and chronic spinal cord injury; cerebral tumors such as gliomas; pain such as peripheral pain and neuropathic pain; hereditary neuropathy such as hereditary motor and sensory neuropathy including Charcot-Marie-Tooth disease, hereditary sensory neuropathy, hereditary motor neuropathy, and hereditary sensory and autonomic neuropathy; cancers such as gastric cancer, prostate cancer, colorectal cancer, Hodgkin lymphoma, cutaneous T cell lymphoma, colon cancer, breast cancer, lung cancer, liver cancer, hepatocellular cancer, sarcoma, oral cancer, pancreatic cancer, bone cancer, bladder cancer, and urothelial cancer.
When administered to a subject, Compound [I] may be formulated into a medical formulation (also referred to as a "pharmaceutical composition" hereinafter) in various forms depending on therapeutic purposes, ages, genders, disease states of subjects, and other conditions. Examples of the formulation include tablets (such as sugar-coated tablets, enteric coated tablets, and film-coated tablets), pills, powders, liquids, suspensions, emulsions, granules, capsules, suppositories, and intramuscular, intradermal, subcutaneous, or intraperitoneal injections (such as liquids and suspensions).
The medical formulation used herein comprises Compound [I] and is prepared by combining Compound [I] and a pharmaceutically acceptable carrier, followed by formulation. The carrier used herein includes commonly used carriers including excipients such as glucose, lactose, sucrose, sodium chloride, glucose, urea, starch, cacao butter, calcium carbonate, hydrogenated vegetable oil, kaolin, talc, and crystalline cellulose; binders such as water, ethanol, propanol, simple syrup, glucose solution, starch solution, gum arabic powders, tragacanth powders, gelatin solution, carboxymethyl cellulose, shellac, methyl cellulose, potassium phosphate, and polyvinylpyrrolidone; disintegrants such as dry starch, sodium alginate, agar powders, laminaran powders, sodium hydrogencarbonate, calcium carbonate, polyoxyethylene sorbitan fatty acid esters, sodium lauryl sulfate, monoglyceride stearate, starch, and lactose; disintegration suppressants such as sucrose, stearin, cacao butter, and hydrogenated oil; absorption promoters such as quaternary ammonium salt and sodium lauryl sulfate; humectants such as glycerin and starch; adsorbents such as starch, lactose, kaolin, bentonite, and colloidal silica; and lubricants such as purified talc, stearate, boric acid powders, and polyethylene glycol.
The amount of a compound of Formula [I] contained in a medical formulation used herein is not limited and is optionally adjusted within a broad range of amounts; e.g., a medical formulation used herein typically comprises 1 to 70% by weight of a compound of Formula [I] to the formulation.
A dosage amount of a compound of Formula [I] comprised in a medical formulation herein (also referred to as a "therapeutically effective amount" herein) may vary and may be optimized depending on dosage regimens, ages, genders, and the extent of diseases of patients, and other conditions; the amount ranges, for example, from 0.01 to 100 mg/kg, preferably 0.1 to 50 mg/kg, of body weight per day in a single dose or multiple doses.
Compound [I] may be used in combination with at least one therapeutic or preventive agent useful for diseases for which Compound [I] is thought to be effective. In one aspect, the agent includes medicaments useful for diseases selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumors, pain, and hereditary neuropathy. In another aspect, the agent includes medicaments useful for diseases selected from cancers, fungal diseases, and infections. The agent may be administered in combination with Compound [I] simultaneously, and/or separately, such as continuously or with a suitable interval in between. The agent may be formulated into a separate formulation from a formulation comprising Compound [I] or into a single formulation comprising both the agent and Compound [I].
The present invention is also described in more detail with reference to Reference Examples, Examples, and Test Examples as below, but is not limited thereto. These examples may be modified without departing from the scope of the invention.
The following abbreviations are used herein.
REX: Reference Example number
EX: Example number
STR: structural formula
RProp: Reference Preparation (The number means that the compound was prepared from corresponding starting materials in a similar manner to a Reference Example compound with the number as a Reference Example number.)
Prop: Preparation (The number means that the compound was prepared from corresponding starting materials in a similar manner to an Example compound with the number as an Example number.)
Data: physicochemical data (NMR1: δ (ppm) in 1H-NMR in dimethyl sulfoxide-d6; NMR2: δ (ppm) in 1H-NMR in CDCl3); NMR3: δ (ppm) in 1H-NMR in CD3OD) or MS: Mass spectrum
9-BBN: 9-borabicyclo[3.3.1]nonane
AcOEt: ethyl acetate
AcOH: acetic acid
AcONa: sodium acetate
BBr3: boron tribromide
BF3OEt2: boron trifluoride - diethyl ether complex
Bn: benzyl
Boc: tert-butoxycarbonyl
Bpin: boronic acid pinacol ester
CDI: 1,1’-carbonyldiimidazole
CH3CN: acetonitrile
Cs2CO3: cesium carbonate
DBU: 1,8-diazabicyclo[5.4.0]-7-undecene
DCC: dicyclohexylcarbodiimide
DCE: 1,2-dichloroethane
DCM: dichloromethane
DEA: diethylamine
DEAD: diethyl azodicarboxylate
DHP: 3,4-dihydro-2H-pyrane
DIBAL: diisobutylaluminum hydride
DIBOC: di-t-butyl dicarbonate
DIPEA: diisopropylethylamine
DMA: N,N-dimethylacetamide
DMAP: 4-(dimethylamino)pyridine
DME: dimethoxyethane
DMF: N,N-dimethylformamide
DMSO: dimethyl sulfoxide
DPPA: diphenylphosphoryl azide
Et2O: diethyl ether
EtOH: ethanol
HCl: hydrochloric acid
Hexane: n-hexane
HATU: 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate
HOBt: 1-hydroxybenzotriazole
IPA: 2-propanol
IPE: diisopropyl ether
K2CO3: potassium carbonate
K3PO4: tripotassium phosphate
KHCO3: potassium hydrogen carbonate
KF: potassium fluoride
KOH: potassium hydroxide
KOAc: potassium acetate
KOtBu: potassium t-butoxide
LAH: lithium aluminum hydride
LDA: lithium diisopropylamide
LHMDS: lithium hexamethyldisilazide
LiOH: lithium hydroxide
MCPBA: m-chloroperoxybenzoic acid
MEK: 2-butanone
MeOH: methanol
MgSO4: magnesium sulfateNaBH4: sodium borohydride
Na2CO3: sodium carbonate
NaH: sodium hydride
NaHCO3: sodium hydrogen carbonate
NH4Cl: ammonium chloride
NaHMDS: sodium hexamethyldisilazide
NaOH: sodium hydroxide
NaOtBu: sodium t-butoxide
Na2SO4: sodium sulfate
n-BuLi: n-butyllithium
NCS: N-chlorosuccinimide
NH3: ammonia
NMP: N-methylpyrrolidone
XPhos: 2-dicyclohexylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl
XPhos Pd G3: (2-dicyclohexylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl)[2-(2'-amino-1,1'-biphenyl)]palladium (II) methanesulfonate
Pd/C: palladium on carbon
Pd2(dba)3: tris(dibenzylideneacetone)dipalladium
Pd(dtbpf)Cl2: 1,1'-bis(di-t-butylphosphino)ferrocene palladium dichloride
Pd(dppf)Cl2: 1,1'-bis(diphenylphosphino)ferrocene]palladium
Pd(OAc)2: palladium acetate
Pd(OH)2-C: palladium hydroxide on carbon
Pd(PPh3)4: tetrakis(triphenylphosphine)palladium
PEG: polyethylene glycol
PPTS: pyridinium p-toluenesulfonate
PtO2: platinum oxide
T3P: propylphosphonic anhydride
t-BuOH: t-butyl alcohol
TEA: triethylamine
TEB: triton extraction buffer
TFA: trifluoroacetic acid
THF: tetrahydrofuran
TMS-Cl: chlorotrimethylsilane
WSC: 3-ethyl-1-(3-dimethylaminopropyl)carbodiimide hydrochloride
ZCl: benzyl chloroformate
The "r.t." in the Examples below basically refers to from about 10°C to about 35°C. The ratios in mixed solvents refer to the volume ratio unless otherwise specified. % refers to % by weight unless otherwise specified.
1H NMR (proton nuclear magnetic resonance spectrum) was determined at room temperature by Fourier transform NMR (any one of Bruker AVANCE III 400 (400 MHz), Bruker AVANCE III 500 HD (500 MHz)), and Bruker AVI 400MHz with a QNP probe, Z gradient.
In silica gel column chromatography, aminopropylsilane-bonded silica gels were used when the term "basic" is described.
MS (mass spectrum) was measured with LC/MS (Waters Acquity SQD/LC, Waters Acquity UPLC H-Class, or Thermo Fisher scientific ITQ 1100). Data described herein are measured values (found). Molecular ion peaks of a free form (such as [M+H]+ and [M-H]-), molecular ion peaks of a free form [M]+ or fragment ion peaks thereof, or sodium-adduct ion peaks of a free form [M+Na]+ are typically observed.
When amino silica gel is described for silica gel column chromatography, silica gel modified with amine (e.g., aminopropylsilane bonded silica gel) is used.
Absolute configurations of compounds were determined by known X-ray crystallography (e.g., Shigeru Ooba and Shigenobu Yano, "Kagakusha no tame no Kiso-Koza 12 X-ray crystallography" (1st ed., 1999)) or estimated from the empirical rules of Shi asymmetric epoxidation (Waldemar Adam, Rainer T. Fell, Chantu R. Saha-Moller and Cong-Gui Zhao: Tetrahedron: Asymmetry 1998, 9, 397-401. Yuanming Zhu, Yong Tu, Hongwu Yu, Yian Shi: Tetrahedron Lett. 1988, 29, 2437-2440).
Reference Examples
Reference Example 1: tert-Butyl (R)-2-(isoindoline-2-carbonyl)-4-(((trifluoromethyl)sulfonyl)oxy)-2,5-dihydro-1H-pyrrole-1-carboxylate
To a solution of (R)-1-(tert-butoxycarbonyl)-4-oxopyrrolidine-2-carboxylic acid (711 mg) in DMF (10 mL) were added isoindoline (554 mg), DIPEA (1.1 mL) and HATU (1.7 g). After stirring at r.t. for 1 hour, the reaction was partitioned between water and AcOEt. The organic phase was washed with water, 2N HCl and brine and then concentrated in vacuo. The crude mixture was purified by flash chromatography (petrol:AcOEt) to give the product (615 mg). To a solution of 1M NaHMDS (2 mL) in THF (25 mL) at -78°C and under N2, was slowly added a solution of the obtained product (615 mg) in THF (10 mL). After 30 minutes a solution of N-Phenyl-bis(trifluoromethanesulfonimide) (665 mg) in THF (5 mL) was slowly added and the reaction was stirred for 1 hour. The reaction was quenched with NH4Cl and extracted with AcOEt. The organic phase was concentrated and the residues was purified by silica gel column chromatography (petrol:AcOEt) to give tert-butyl (R)-2-(isoindoline-2-carbonyl)-4-oxopyrrolidine-1-carboxylate (735 mg).
Reference Example 2: 2-Benzyl-5-bromo-6-methoxyisoindoline
A solution of 1-bromo-4,5-bis(bromomethyl)-2-methoxybenzene (1.20 g) and benzylamine (0.422 ml) in DMF (24 ml) was cooled to 0°C, and NaH (0.295 g) was added. The reaction was allowed to warm to r.t., and stirred for 3h. sat. NH4Cl aq. was added, and the aqueous solution was extracted with AcOEt (x2). The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated. Purification via silica gel column chromatography (Hexane : AcOEt) afforded 727 mg of 2-benzyl-5-bromo-6-methoxyisoindoline.
Reference Example 3: 2-(6-Methoxyisoindolin-5-yl)-N-phenylacetamide hydrochloride
In a 300-mL round-bottom flask, were placed 2-benzyl-5-bromo-6-methoxyisoindoline (8.45 g), Pd2(dba)3 (1.216 g), tri-t-butylphosphonium tetrafluoroborate (3.08 g), and zinc fluoride (6.86 g). The vessel was evacuated and backfilled with N2, then DMF (160 ml) and 1-(tert-butyldimethylsilyloxy)-1-methoxyethene (23.17 ml) were added. The reaction was stirred at 80°C for 18 h. After cooling, sat. NH4Cl aq. was added, and the aqueous solution was extracted with AcOEt (x4). The combined organic layers were dried over Na2SO4 + silicagel, filtered, and concentrated. Purification via silica gel column chromatography (Hexane : AcOEt) afforded the product (7.72 g). To a solution of the obtained product (2.35 g) in toluene (80 ml) under N2, was added aniline (0.827 ml) and bis(trimethylaluminum)-1,4-diazabicyclo[2.2.2]octane adduct (2.90 g). The mixture was refluxed for 4 h. The reaction mixture was poured into sat. Rochelle salt aq. and stirred for 30min. The insoluble materials were removed by filtration through Celite washing with AcOEt. The aqueous phase of the filtrate was extracted with AcOEt (x2). The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated. Purification via silicagel column chromatography (Hexane : AcOEt) afforded the product (1.79 g). A solution of the obtained product (1.00 g), HCl (4N in AcOEt) (1.342 ml), and Pd(OH)2-C (20% wet) (200 mg) in EtOH/DMF (1/1) (4 ml) was stirred under H2 at r.t. for 16h. The reaction was filtered through Celite washing with H2O and EtOH. The solvents were removed by azeotropic evaporation with toluene. The residue was triturated in AcOEt, and the solids were collected by filtration. After drying in vacuo at 80°C for 9 h, 2-(6-methoxyisoindolin-5-yl)-N-phenylacetamide hydrochloride (0.86 g) was obtained.
Reference Example 4: 3-Methyl-7-(piperazin-1-yl)thieno[2,3-c]pyridine dihydrochloride
A mixture of piperazine (1782 mg) and 7-chloro-3-methylthieno[2,3-c]pyridine (380 mg) was heated at 130°C for 2 h. After cooling to r.t., water and AcOEt were added to the reaction mixture and vigorously stirred for a while. The biphasic solution was extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered off and concentrated in vacuo. The resultant residue was purified by amino silica gel column chromatography (ethyl acetate/MeOH). The obtained free base was converted to the HCl salt using 1 M HCl/EtOH to give 297 mg of 3-methyl-7-(piperazin-1-yl)thieno[2,3-c]pyridine dihydrochloride.
Reference Example 5: 1-(3-(Furan-3-yl)-4-methylpyridin-2-yl)piperazine hydrochloride
To a solution of 1-(3-bromo-4-methylpyridin-2-yl)piperazine hydrochloride (890 mg) in DMF (20 ml) were added DIBOC (0.847 ml) and DMAP (37.2 mg) at 0°C. After being stirred at r.t. overnight, the reaction mixture was diluted with H2O and extracted with AcOEt. The combined organic layers were washed with H2O and brine, dried over MgSO4, filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (Hexane : AcOEt) to give the product. A mixture of the obtained product, furan-3-boronic acid (460 mg), 2 M Na2CO3 aq. (4.11 ml) and 1,1'-Bis(diphenylphosphino)ferrocene-palladium (II) dichloride dichloromethane complex (112 mg) in THF (10 ml) was heated at reflux under N2 atmosphere overnight. The volatiles were evaporated in vacuo. The resultant residue was purified by silica gel column chromatography (Hexane : AcOEt) to give the product. To a solution of the obtained product in AcOEt was added 4N HCl-AcOEt. After being stirred at r.t. overnight, the resultant precipitate was collected by filtration and dried to give 684 mg of 1-(3-(furan-3-yl)-4-methylpyridin-2-yl)piperazine hydrochloride.
Reference Example 6: (S)-5-Methyl-2-(pyrrolidin-3-ylmethyl)thiazole hydrochloride
To a mixture of nickel (II) chloride, dimethoxyethane adduct (4.16 mg) and 4,4'-di-tert-butyl-2,2'-dipyridyl (5.08 mg) was added DME (dry) (20 mL) under N2 atmosphere. After being stirred at r.t. for 5 min, tert-butyl (R)-3-(bromomethyl)pyrrolidine-1-carboxylate (1.00 g) in DME (dry) (25 mL), 2-bromo-5-methyl thiazole (0.401 ml), tris(trimethylsilyl)silane (1.168 ml), (4,4'-di-t-butyl-2,2'-bipyridine)bis[3,5-difluoro-2-(5-trifluoromethyl-2-pyridinyl-kN)phenyl-kC]iridium (III) hexafluorophosphate (0.042 g) and 2,6-lutidine (0.882 ml) were added to the mixture. The solution was divided into 10 vials and they were irradiated by LED light for 2 h. After cooling to r.t., the reaction mixtures were all combined using AcOEt and the solvent was concentrated. The solids precipitated were removed by filtration washing with AcOEt-hexane. The filtrate was purified via silica gel column chromatography (Hexane : AcOEt) to afford the product. To a solution of the obtained product in AcOEt/MeOH (1/1) (6 ml) was added 4M HCl in AcOEt (6 ml), and the reaction mixture was stirred at r.t. overnight. The solvent was removed by evaporation. After drying, (S)-5-methyl-2-(pyrrolidin-3-ylmethyl)thiazole hydrochloride (142 mg) was obtained.
Reference Example 7: ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(5-methoxy-6-(quinolin-2-ylmethyl)isoindolin-2-yl)methanone
To a solution of (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid (230 mg), 2-((6-methoxyisoindolin-5-yl)methyl)quinoline dihydrochloride (308 mg), and triethylamine (0.590 ml) in DCM (5 ml) were added 50% T3P in AcOEt solution (0.630 ml). The reaction mixture was stirred at r.t. for 2 h. The solvent was removed by evaporation. The residue was purified via silica gel column chromatography (Hexane : AcOEt) to afford the product. To a solution of the obtained product (310 mg) in AcOEt/MeOH (1/1) (10 ml) was added 4M HCl in AcOEt (10 ml), and the reaction mixture was stirred at r.t. overnight. The solvent was concentrated azeotroped with toluene. After drying in vacuo at 70°C for 6 h, the product was obtained. The obtained product was dissolved in MeOH and treated with sat. NaHCO3 aq. The aqueous phase was extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered, concentrated, and dried to afford ((2R,4S)-4-(3-chlorophenyl)pyrrolidin-2-yl)(5-methoxy-6-(quinolin-2-ylmethyl)isoindolin-2-yl)methanone (170 mg).
Reference Example 8: 2-((6-Methoxyisoindolin-5-yl)methyl)quinoline dihydrochloride
A mixture of 2-benzyl-5-bromo-6-methoxyisoindoline (2.00 g), Pd2(dba)3 (0.288 g), xantphos (0.546 g) and potassium 2-(quinolin-2-yl)acetate (4.25 g) was heated at 130°C for 5 h under N2 atmosphere. After cooling to r.t., H2O was added and the aqueous solution was extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated. Purification via silica gel column chromatography (Hexane : AcOEt) afforded the product. To a solution of the obtained product in DCM (17 mL) cooled to 0°C was added 1-chloroethyl chloroformate (0.306 mL) slowly. The reaction mixture was stirred at 0°C for 1 h. After removal of the solvent, the intermediate (carbamate) was dissolved in MeOH (60 ml) and refluxed for 1 h. After removal of the solvent, the residue was triturated in AcOEt and the solids precipitated were collected by filtration and dried to give 790 mg of 2-((6-methoxyisoindolin-5-yl)methyl)quinoline dihydrochloride.
Reference Example 9: 4-Chloro-N-(2-(isoindolin-5-yl)ethyl)aniline
To a solution of 2-(2-(tert-butoxycarbonyl)isoindolin-5-yl)acetic acid (728 mg), 4-chloroaniline (402 mg) and triethylamine (1.830 ml) in DCM (15 ml) was added 50% T3P in AcOEt solution (2.344 ml). After being stirred at r.t. overnight, the solvent was removed by evaporation. Purification via silica gel column chromatography (Hexane : AcOEt) afforded the product. To a solution of the obtained product in AcOEt/MeOH (1/1) (25 ml) was added 4M HCl in AcOEt (25 ml) and the reaction mixture was stirred at r.t. overnight.
The solvent was concentrated and the solids precipitated were triturated in AcOEt to give the product. To a solution of the obtained product in THF (10 ml) was slowly added NaBH4 (129 mg). After cooling to 0°C, BF3OEt2 (0.647 ml) was slowly added to the suspension. The reaction was gradually allowed to warm to r.t. and stirred for 1 h, then heated at reflux for additional 3 h. Ice water was added with vigorous stirring. The aqueous phase was basified with 5 N NaOH to pH 10 or below and extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered, concentrated and dried to give 232 mg of 4-chloro-N-(2-(isoindolin-5-yl)ethyl)aniline.
Reference Example 10: 1-(3-(Furan-3-yl)-6-methoxypyridin-2-yl)piperazine hydrochloride
A mixture of tert-butyl 4-(3-bromo-6-methoxypyridin-2-yl)piperazine-1-carboxylate (1 g), furan-3-boronic acid (0.451 g), 2M Na2CO3 aq. (4.03 ml) and 1,1'-Bis(diphenylphosphino)ferrocene-palladium (II) dichloride dichloromethane complex (0.110 g) in THF (10 ml) was heated at reflux for 4 h under N2 atmosphere. After cooling to r.t., the resultant residue was purified by silica gel column chromatography (Hexane : AcOEt) to give the product. To a solution of the obtained product in AcOEt was added 4N HCl-AcOEt. The reaction mixture was stirred at r.t. overnight. The resultant precipitate was collected by filtration and dried to give 750 mg of 1-(3-(furan-3-yl)-6-methoxypyridin-2-yl)piperazine hydrochloride.
Reference Example 11: 2,2'-(Isoindoline-5,6-diyl)dibenzonitrile hydrochloride
A mixture of tert-butyl 5,6-dichloroisoindoline-2-carboxylate (360 mg), XPhos Pd G3 (42.3 mg), K3PO4 (863 mg), 2-cyanoboronic acid pinacol ester (715 mg) in 1,4-dioxane (7 ml) was heated at 80°C for 4h, then, 100°C for 4 h. After cooling to r.t., the reaction mixture was diluted with water and extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated. Purification via silicagel column chromatography (Hexane : AcOEt) afforded the product. To a solution of the obtained product in AcOEt/MeOH (1/1) (5 ml) was added 4M HCl in AcOEt (5 ml), and the reaction mixture was stirred at r.t. overnight. The solvent was concentrated azeotroped with toluene. The residue was triturated in AcOEt and the solids precipitated were collected by filtration. After drying, 2,2'-(isoindoline-5,6-diyl)dibenzonitrile hydrochloride (126 mg) was obtained.
Reference Example 12: N-(2-(6-Methoxyisoindolin-5-yl)ethyl)aniline dihydrochloride
A mixture of 2-benzyl-5-bromo-6-methoxyisoindoline (1.33 g), XPhos Pd G3 (0.177 g), K3PO4 (1.774 g) and (trans)-1-Ethoxyethene-2-boronic acid pinacol ester (1.062 ml) in THF/H2O (4/1) (15 ml) was heated at 60°C overnight. After cooling, H2O was added and the aqueous phase was extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated. Purification via silica gel column chromatography (Hexane : AcOEt) afforded the product. A solution of the obtained product and HCl (5N in H2O) (0.7 ml) in acetone (15 ml) was heated at reflux for 4 h. After cooling, the reaction was diluted with H2O and neutralized with 5N NaOH aq. The aqueous phase was extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated. Purification via silica gel column chromatography (Hexane : AcOEt) afforded the product. To a solution of the obtained product and aniline (0.055 ml) in DCE (3 ml) was added sodium triacetoxyborohydride (158 mg). The reaction mixture was stirred at r.t. for 15 h. Sat. NaHCO3 was added to the reaction mixture and the aqueous phase was extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated. Purification via silica gel column chromatography (Hexane : AcOEt) afforded the product. A solution of the obtained product, HCl (4M in AcOEt) (1.841 ml) and Pd(OH)2-C (20% wet) (180 mg) in EtOH/H2O (20/1) (21 ml) was stirred under H2 at r.t. for 19 h. The reaction was filtered through Celite washing with EtOH. The filtrate was concentrated and dried to afford N-(2-(6-methoxyisoindolin-5-yl)ethyl)aniline dihydrochloride (570 mg).
Reference Example 13: 1-(3-(Furan-3-yl)pyridin-2-yl)piperazine dihydrochloride
A mixture of tert-butyl 4-(3-bromopyridin-2-yl)piperazine-1-carboxylate (2 g), Furan-3-boronic acid (0.981 g), Na2CO3 (8.77 ml), 1,1'-Bis(diphenylphosphino)ferrocene-palladium (II) dichloride dichloromethane complex (0.239 g) in THF (20 ml) was heated at reflux for 5 h under N atmosphere. After cooling to r.t., the reaction mixture was filtered through Celite. The filtrate was concentrated in vacuo. The resultant residue was purified by MPLC (Hexane : AcOEt) to give the product. To a solution of the obtained product in AcOEt was added HCl (4M in AcOEt). The reaction mixture was stirred at r.t. overnight. The resultant precipitate was collected by filtration and dried to give 1.28 g of 1-(3-(furan-3-yl)pyridin-2-yl)piperazine dihydrochloride.
Reference Example 14: tert-Butyl (2R,4S)-2-(5-bromo-6-methoxyisoindoline-2-carbonyl)-4-phenylpyrrolidine-1-carboxylate
A solution of 1-bromo-4,5-bis(bromomethyl)-2-methoxybenzene (2.20 g) and O-t-Butyl carbamate (0.829 g) in DMF (44 ml) was cooled to 0°C and NaH (0.541 g) was added. The reaction was allowed to warm to r.t., and stirred for 3 h. Sat. NH4Cl aq. was added and the aqueous solution was extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated. Purification via silica gel column chromatography (Hexane : AcOEt) afforded 1.59 g of the product. HCl (4M in AcOEt) (4 ml) was added to the obtained product (200 mg) and the reaction was stirred at r.t. for 2h.
The reaction was basified with 5N NaOH aq. and the aqueous solution was extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated. Purification via amino silica gel column chromatography (AcOEt : MeOHt) afforded the product. To a solution of (2R,4S)-1-(tert-butoxycarbonyl)-4-phenylpyrrolidine-2-carboxylic acid (74.5 mg), the obtained product (70 mg), WSC (63.7 mg) and HOBt (50.9 mg) in DMF (2 ml) was added DIPEA (0.112 ml). The reaction mixture was stirred at r.t. for 10 h. The reaction mixture was diluted with H2O and the aqueous phase was extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated. Purification via silica gel column chromatography (Hexane : AcOEt) afforded 108 mg of tert-butyl (2R,4S)-2-(5-bromo-6-methoxyisoindoline-2-carbonyl)-4-phenylpyrrolidine-1-carboxylate.
Reference Example 15: N-(6-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)naphthalen-2-yl)acetamide
A mixture of N-(6-bromonaphthalen-2-yl)acetamide (1.87 g), bis(pinacolato)diboron (2.70 g), potassium acetate (1.390 g) and 1,1'-bis(diphenylphosphino)ferrocene-palladium (II) dichloride dichloromethane complex (0.289 g) in dioxane (20 ml) was heated at reflux for 2 h under N2 atmosphere. After cooling to r.t., The reaction mixture was diluted with AcOEt and filtered through Celite. The filtrate was concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (Hexane : AcOEt) to give 2.14 g of N-(6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)naphthalen-2-yl)acetamide.
Reference Example 16: (2R,4S)-1-(tert-Butoxycarbonyl)-4-(3-cyclopropylphenyl)pyrrolidine-2-carboxylic acid
A mixture of 1-(tert-butyl) 2-methyl (R)-4-(((trifluoromethyl)sulfonyl)oxy)-2,5-dihydro-1H-pyrrole-1,2-dicarboxylate (1429 mg), 2-(3-cyclopropylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (976 mg), palladium (II) acetate (11.97 mg), XPhos (30.5 mg) and potassium fluoride (511 mg) in THF/H2O (4:1) (5 ml) was heated at 60°C overnight under N2 atmosphere. After cooling to r.t., the reaction mixture was purified by silica gel column chromatography (Hexane : AcOEt) to give the product. A mixture of the obtained product and Silia Cat Pd(0) (80 mg) in AcOEt (10 mL) was stirred at r.t. for 5 h under H2 atmosphere. The reaction mixture was filtered through Celite and the filtrate was concentrated in vacuo. The resultant residue was purified by amino silica gel column chromatography (Hexane : AcOEt) to give the product. To a solution of the obtained product in MeOH (3 ml) was added 5 N NaOH (0.23 mL). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. The resultant residue was neutralized with 5 N HCl and extracted with AcOEt. The combined organic layers were washed with brine, dried over MgSO4, filtered off and concentrated in vacuo to give 76 mg of (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-cyclopropylphenyl)pyrrolidine-2-carboxylic acid.
Reference Example 17: (2R,4S)-1-(tert-Butoxycarbonyl)-4-(6-methoxynaphthalen-2-yl)pyrrolidine-2-carboxylic acid
The title compound was obtained by similar procedures to Reference Example 16.
Reference Example 18: (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid
A mixture of 3-Nitrophenylboronic acid (16.01 g), tert-butyl (R)-2-(isoindoline-2-carbonyl)-4-(((trifluoromethyl)sulfonyl)oxy)-2,5-dihydro-1H-pyrrole-1-carboxylate (30.0 g), Pd(OAc)2 (0.485 g), XPhos (1.219 g) and KF (8.05 ml) in THF/H2O (4:1) (250 ml) was stirred at r.t. for 3 days under N2 atmosphere. The reaction mixture was diluted with AcOEt and water. The resultant suspension was filtered through Celite. The filtrate was extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane:AcOEt). Then, the obtained solid was crystallized from AcOEt/IPE to give the product. A mixture of the obtained product and Silia Cat Pd(0) (1.97 g) in AcOEt (200 ml) was stirred for 9 h at r.t. under H2 atmosphere. The reaction mixture was filtered through Celite. The filtrate was concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane:AcOEt) to give the product. To a solution of the obtained product and copper (II) chloride (11.08 g) in CH3CN (290 ml) was added tert-butylnitrite (14.37 ml) from a dropping funnel for 10 min. at 50°C. The reaction mixture was stirred for 2 h at the same temperature. After cooling to r.t., the reaction mixture was diluted with water (200 mL) and extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane:AcOEt) to give the product. To a solution of the obtained product in EtOH (100 ml) was added 5 N NaOH (8.92 ml). The reaction mixture was stirred for 3 h at r.t. The reaction mixture was neutralized with 5 N HCl at 0°C. The volatiles were evaporated in vacuo. The resultant aqueous phase was extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered off and concentrated in vacuo to give 4.816 g of (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid.
Reference Example 19: 3-Fluoro-2-(isoindolin-5-yl)benzonitrile hydrochloride
A mixture of 2-bromo-3-fluorobenzonitrile (198 mg), tert-butyl 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)isoindoline-2-carboxylate (560 mg), 0.5M K3PO4 aq. (3.95 ml) and XPhos Pd G3 (33.5 mg) in THF (16 ml) was heated at 60°C for 4 h under N2 atmosphere. The reaction mixture was diluted with H2O and extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered and concentrated. Purification via silica gel column chromatography (Hexane : AcOEt) afforded the product. To a solution of the obtained product in AcOEt/MeOH (1/1) (9 ml) was added 4M HCl in AcOEt (9 ml) and the reaction mixture was stirred at r.t. overnight. The solvent was concentrated and the solids appeared were triturated in AcOEt. The solids were collected by filtration.
After drying, 3-Fluoro-2-(isoindolin-5-yl)benzonitrile hydrochloride (195 mg) was obtained.
Reference Example 20: (2R,4S)-1-(tert-Butoxycarbonyl)-4-(3-propylphenyl)pyrrolidine-2-carboxylic acid
The title compound was obtained by similar procedures to Reference Example 16.
Reference Example 21: (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-(trifluoromethyl)phenyl)pyrrolidine-2-carboxylic acid
The title compound was obtained by similar procedures to Reference Example 16.
Reference Example 22: 1-(2-(Furan-3-yl)phenyl)piperazine hydrochloride
The title compound was obtained by similar procedures to Reference Example 10.
Reference Example 23: N-(6-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)quinolin-2-yl)acetamide
The title compound was obtained by similar procedures to Reference Example 15.
Examples
Example 1: ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(isoindolin-2-yl)methanone hydrochloride
To a solution of tert-butyl (2R)-2-(2,3-dihydro-1H-isoindole-2-carbonyl)-4-(trifluoromethanesulfonyloxy)-2,5-dihydro-1H-pyrrole-1-carboxylate (400 mg) in dioxane (5 mL) were added 3-chlorophenylboronic acid (162 mg), Pd(dtbpf)Cl2 (11.3 mg), 2M Na2CO3 (1 mL). The reaction was stirred under N2 at 100°C for 1 hour. The reaction was partitioned between water and AcOEt, the combined organics were concentrated in vacuo and the residue purified by silica gel column chromatography (petrol:AcOEt) to give the product (182 mg). The obtained product (182 mg) and PtO2 (18 mg) were combined in MeOH (5 mL) and the suspension was stirred at r.t. under H2 for 3 hours. The reaction was filtered through Celite, the filtrate was concentrated and the residue was purified by silica gel column chromatography (petrol:AcOEt) to give the product (54 mg). 4M HCl in dioxane (2 mL) was added to the obtained product (54 mg) and the reaction was stirred at r.t. for 2 hours. The solvent was concentrated in vacuo and the residues was triturated in Et2O. The solid was collected by filtration to give ((2R,4S)-4-(3-chlorophenyl)pyrrolidin-2-yl)(isoindolin-2-yl)methanone hydrochloride (34 mg).
Example 2 and Example 3: 5-(4-((3S,5R)-5-(Isoindoline-2-carbonyl)pyrrolidin-3-yl)phenyl)pyrrolidin-2-one (Isomer 1 and Isomer 2)
To a solution of 1-(tert-butyl) 2-methyl (R)-4-(((trifluoromethyl)sulfonyl)oxy)-2,5-dihydro-1H-pyrrole-1,2-dicarboxylate (1.3 g) in dioxane (15 mL) were added Pd(dppf)Cl2 (72 mg,), KOAc (1.0 g) and bis(pinacolato)diboron (1.5 g) and the reaction was stirred under N2 at 90°C overnight. Then 5-(4-bromophenyl)pyrolodin-2-one (704 mg), 2M Na2CO3 (4.4 mL) and Pd(PPh3)4 (107 mg) were added and the resulting mixture was stirred under N2 at 90°C overnight. The reaction was quenched with water and extracted with AcOEt. The organic phase was concentrated and the crude material was purified by silica gel column chromatography (isohexane : AcOEt) to give the product (770 mg). A suspension of obtained product (770 mg) and 10% Pd/C (212 mg) in MeOH (50 mL) was stirred under H2 at r.t. for 1.5 hours. The reaction was filtered through Celite and the solvent was concentrated to give the product (700 mg) as a mixture of diastereomers. LiOH.H2O (91 mg) was added to a solution of the obtained product (700 mg) in MeOH (12 mL) and water (12 mL) and the reaction mixture was stirred at 60°C overnight. The solvent was concentrated and the product as a lithium salt was used in the next step without further purification. To a solution of the obtained product in DMF (30 mL) were added isoindoline (0.36 mL), DIPEA (0.47 mL) and HATU (1.0 g) and the mixture was stirred at r.t. overnight. The reaction was quenched with NaHCO3 and extracted with AcOEt, the organic phase was concentrated to give the product (650 mg) which was used in the next step without any further purification. 4M HCl in dioxane (1.7 mL) was added to a solution of the obtained product (650 mg) in AcOEt (14 mL) and the mixture was stirred at r.t. overnight. The reaction was concentrated, the residue was diluted with NaHCO3 and extracted with AcOEt. The organic phase was concentrated, the residues was filtered through a SCX column (eluted with 3M NH3) followed by purification by silica gel column chromatography (DCM:MeOH:NH3) to give 5-(4-((3S,5R)-5-(isoindoline-2-carbonyl)pyrrolidin-3-yl)phenyl)pyrrolidin-2-one (160 mg) as a mixture of diastereomers. The two isomers were separated by chiral HPLC (Waters Thar Investigator with Waters 2998 UV/Vis PDA detector, YMC AMYLOSE-C 10 x 250mm, 5 μm 55/45 MeOH (0.1% DEA) / CO2, 15 ml/min, 120 bar, 40°C). The one isomer eluted firstly was identified as Isomer 1a, and the other isomer eluted secondly was identified as Isomer 2a, respectively. Isomer 1a was treated with 4M HCl in dioxane to form the hydrochloride salt that was identified as Isomer 1 (Example 2). Isomer 2a was also treated with 4M HCl in dioxane to form its hydrochloride salt form that was then identified as Isomer 2 (Example 3).
Example 4: ((2R,4S)-4-(4-Chlorophenyl)pyrrolidin-2-yl)(isoindolin-2-yl)methanone hydrochloride
To a solution of tert-butyl (2R)-2-(2,3-dihydro-1H-isoindole-2-carbonyl)-4-(trifluoromethanesulfonyloxy)-2,5-dihydro-1H-pyrrole-1-carboxylate (400 mg) in dioxane (5 mL) were added 4-chlorobenzeneboronic acid (162 mg), Pd(PPh3)4 (20 mg) and 2M Na2CO3 (1 mL). The reaction was stirred under N2 at 100°C for 2 hours. The reaction was partitioned between water and AcOEt, the organic phase was concentrated and the residue was purified by silica gel column chromatography (petrol:AcOEt) to give the product (217 mg). The obtained product (217 mg) and PtO2 (22 mg) were combined in MeOH (5 mL). The suspension was stirred at r.t. under H2 for 3 hours. The reaction mixture was filtered through Celite, the filtrate was concentrated and the residue was purified by reversed phase silica gel column chromatography (KP-C18, water:acetonitrile) to give the product (36 mg). 4M HCl in dioxane (2 mL) was added to the obtained product (36 mg) and the reaction was stirred at r.t. for 2 hours. The solvent was concentrated and the residues was triturated in Et2O. The solid was collected by filtration and dried in vacuo to give ((2R,4S)-4-(4-chlorophenyl)pyrrolidin-2-yl)(isoindolin-2-yl)methanone hydrochloride (14 mg).
Example 5: Isoindolin-2-yl((2R,4S)-4-phenylpyrrolidin-2-yl)methanone hydrochloride
To a suspension of (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid (240 mg), isoindoline (0.112 ml), WSC (205 mg) and HOBt (164 mg) in DMF (5 ml) was added DIPEA (0.360 ml). The reaction mixture was stirred overnight. The reaction mixture was diluted with AcOEt and water and extracted with AcOEt. The combined organic layers were washed with water and brine, dried over Na2SO4, filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (DCM : AcOEt) to give the product. To a solution of the obtained product (245 mg) in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml). The reaction mixture was stirred at r.t. overnight.
The volatiles were evaporated in vacuo. The resultant residue was dissolved in water, basified with sat. NaHCO3 aq. and extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered off and concentrated in vacuo to give 167 mg of isoindolin-2-yl((2R,4S)-4-phenylpyrrolidin-2-yl)methanone hydrochloride.
Example 6: ((2R,4S)-4-Phenylpyrrolidin-2-yl)(3-(pyridin-2-ylmethyl)pyrrolidin-1-yl)methanone dihydrochloride
To a suspension of (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid (150 mg), 2-(pyrrolidin-3-ylmethyl)pyridine dihydrochloride (145 mg), WSC (128 mg) and HOBt (102 mg) in DMF (5 ml) was added DIPEA (0.225 ml). The reaction mixture was stirred at r.t. 3 days. The reaction mixture was diluted with AcOEt and water and extracted with AcOEt. The combined organic layers were washed with water and brine, and dried over Na2SO4, filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (AcOEt : MeOH) to give the product. To a solution of the obtained product in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. The resultant residue was dissolved in water (5 mL), basified with sat. NaHCO3 aq. and extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered off and concentrated in vacuo to give 73.6 mg of the product. The obtained free base was converted to the HCl salt using 1 M HCl-EtOH. The HCl salt was washed with AcOEt and dried at 45°C overnight under reduced pressure to give 39 mg of ((2R,4S)-4-phenylpyrrolidin-2-yl)(3-(pyridin-2-ylmethyl)pyrrolidin-1-yl)methanone dihydrochloride.
Example 7: 2-(4-((2R,4S)-4-Phenylpyrrolidine-2-carbonyl)piperazin-1-yl)nicotinonitrile dihydrochloride
To a suspension of (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid (150 mg), 2-(1-Piperazinyl)-3-pyridinecarbonitrile (116 mg), WSC (128 mg) and HOBt (102 mg) in DMF (5 ml) was added DIPEA (0.270 ml). The reaction mixture was stirred for 3 days at r.t. The reaction mixture was diluted with AcOEt and water and extracted with AcOEt. The combined organic layers were washed with water and brine, dried over Na2SO4, filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane : AcOEt) to give the product. To a solution of the obtained product in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml. The reaction mixture was stirred at r.t. overnight. The precipitated reaction mixture was diluted with IPE. The insoluble was collected by filtration and dried at 40°C under reduced pressure for 8 h to give 213 mg of 2-(4-((2R,4S)-4-phenylpyrrolidine-2-carbonyl)piperazin-1-yl)nicotinonitrile dihydrochloride.
Example 8: 2-(4-((2R,4S)-4-(3-Chlorophenyl)pyrrolidine-2-carbonyl)piperazin-1-yl)nicotinonitrile dihydrochloride
To a suspension of (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid (200 mg), 2-(1-Piperazinyl)-3-pyridinecarbonitrile (139 mg), WSC (153 mg) and HOBt (122 mg) in DMF (5 ml) was added DIPEA (0.322 ml). The reaction mixture was stirred overnight at r.t. The reaction mixture was diluted with AcOEt and water and extracted with AcOEt. The combined organic layers were washed with water and brine, dried over Na2SO4, filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane : AcOEt) to give the product. To a solution of the obtained product (290 mg) in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. The resultant residue was washed with IPE and dried at 45°C overnight under reduced pressure to give 238 mg of 2-(4-((2R,4S)-4-(3-chlorophenyl)pyrrolidine-2-carbonyl)piperazin-1-yl)nicotinonitrile dihydrochloride.
Example 9: 2-(2-((2R,4S)-4-(3-Chlorophenyl)pyrrolidine-2-carbonyl)-6-methoxyisoindolin-5-yl)-N-phenylacetamide hydrochloride
To a suspension of (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid (120 mg), 2-(6-methoxyisoindolin-5-yl)-N-phenylacetamide hydrochloride (141 mg), WSC (92 mg) and HOBt (73.3 mg) in DMF (5 ml) was added DIPEA (0.322 ml). The reaction mixture was stirred for 3 days at r.t. The reaction mixture was diluted with AcOEt and water and extracted with AcOEt. The combined organic layers were washed with water and brine and dried over Na2SO4, filtered off, concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane : AcOEt) to give the product. To a solution of the obtained product in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. The resultant residue was dissolved in small amount of DCM and IPE was added to the solution. Then, DCM was only evaporated in vacuo. The resultant precipitate was collected by filtration and dried at 45°C overnight under reduced pressure to give 36 mg of 2-(2-((2R,4S)-4-(3-chlorophenyl)pyrrolidine-2-carbonyl)-6-methoxyisoindolin-5-yl)-N-phenylacetamide hydrochloride.
Example 10: ((2R,4S)-4-Phenylpyrrolidin-2-yl)(4-(thieno[2,3-c]pyridin-7-yl)piperazin-1-yl)methanone dihydrochloride
To a suspension of (2R,4S)-1-(tert-butoxycarbonyl)-4-phenylpyrrolidine-2-carboxylic acid (150 mg), 7-(piperazin-1-yl)thieno[2,3-c]pyridine hydrochloride (158 mg), WSC (128 mg) and HOBt (102 mg) in DMF (5 ml) was added DIPEA (0.360 ml). The reaction mixture was stirred overnight at r.t. The reaction mixture was diluted with AcOEt and water and extracted with AcOEt. The combined organic layers were washed with water and brine, dried over Na2SO4, filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane : AcOEt) to give 233 mg of the product. To a solution of the obtained product (230 mg) in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. The resultant residue was washed with AcOEt/IPA and dried at 60°C for 6 h to give 181 mg of ((2R,4S)-4-phenylpyrrolidin-2-yl)(4-(thieno[2,3-c]pyridin-7-yl)piperazin-1-yl)methanone dihydrochloride.
Example 11: ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(4-(thieno[2,3-c]pyridin-7-yl)piperazin-1-yl)methanone dihydrochloride
To a suspension of (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid (110 mg), 7-(piperazin-1-yl)thieno[2,3-c]pyridine hydrochloride (104 mg), WSC (84 mg) and HOBt (67.2 mg) in DMF (5 ml) was added DIPEA (0.236 ml). The reaction mixture was stirred for 3 days at room temperature. The reaction mixture was diluted with AcOEt and water and extracted with AcOEt. The combined organic layers were washed with water and brine, dried over Na2SO4, filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane : AcOEt). To a solution of the obtained product in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml). The reaction mixture was stirred at room temperature overnight. The volatiles were evaporated in vacuo. The resultant residue was washed with AcOEt/IPA and dried at 40°C for 2 days under reduced pressure to give 127 mg of ((2R,4S)-4-(3-chlorophenyl)pyrrolidin-2-yl)(4-(thieno[2,3-c]pyridin-7-yl)piperazin-1-yl)methanone dihydrochloride.
Example 12: ((2R,4S)-4-Phenylpyrrolidin-2-yl)(4-(thieno[2,3-c]pyridin-7-yl)piperidin-1-yl)methanone dihydrochloride
To a suspension of (2R,4S)-1-(tert-butoxycarbonyl)-4-phenylpyrrolidine-2-carboxylic acid (50 mg), 7-(piperidin-4-yl)thieno[2,3-c]pyridine dihydrochloride (60.0 mg), WSC (42.8 mg) and HOBt (34.2 mg) in DMF (5 ml) was added DIPEA (0.150 ml). The reaction mixture was stirred for 4 h at r.t. The reaction mixture was diluted with water and extracted with AcOEt. The combined organic layers were washed with water and brine, dried over Na2SO4, filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane : AcOEt) to give the product. To a solution of the obtained product in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. The resultant residue was washed with AcOEt/IPA and dried at 60°C overnight to give 38 mg of ((2R,4S)-4-phenylpyrrolidin-2-yl)(4-(thieno[2,3-c]pyridin-7-yl)piperidin-1-yl)methanone dihydrochloride.
Example 13: (4-(Benzo[b]thiophen-7-yl)piperazin-1-yl)((2R,4S)-4-(3-chlorophenyl)pyrrolidin-2-yl)methanone dihydrochloride
To a suspension of (2R,4S)-1-(tert-butoxycarbonyl)-4-(3-chlorophenyl)pyrrolidine-2-carboxylic acid (120 mg), 1-(benzo[b]thiophen-7-yl)piperazine dihydrochloride (129 mg), WSC (92 mg) and HOBt (73.3 mg) in DMF (5 ml) was added DIPEA (0.322 ml). The reaction mixture was stirred for 3 days at r.t. The reaction mixture was poured into water. The resultant precipitate was collected by filtration and dried at 60°C overnight. The obtained solid was purified by silica gel column chromatography (hexane : AcOEt) to give the product. To a solution of the obtained product in AcOEt (2 ml) was added 4 N HCl-AcOEt (2 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. The resultant residue was washed with AcOEt/IPA and dried at 60°C overnight to give 149 mg of (4-(benzo[b]thiophen-7-yl)piperazin-1-yl)((2R,4S)-4-(3-chlorophenyl)pyrrolidin-2-yl)methanone dihydrochloride.
Example 14: (5-Methoxy-6-(2-(phenylamino)ethyl)isoindolin-2-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone dihydrochloride
The title compound was obtained by similar procedures to Example 5.
Example 15: ((2R,4S)-4-Phenylpyrrolidin-2-yl)(4-(thieno[3,2-d]pyrimidin-4-yl)piperazin-1-yl)methanone dihydrochloride
The title compound was obtained by similar procedures to Example 5.
Example 16: (4-(3-(Furan-3-yl)pyridin-2-yl)piperazin-1-yl)((2R,4S)-4-(6-methoxynaphthalen-2-yl)pyrrolidin-2-yl)methanone dihydrochloride
To a solution of (2R,4S)-1-(tert-butoxycarbonyl)-4-(6-methoxynaphthalen-2-yl)pyrrolidine-2-carboxylic acid (78 mg) and 1-(3-(furan-3-yl)pyridin-2-yl)piperazine dihydrochloride (95 mg) in DCM (2 ml) were added TEA (0.146 ml) followed by 50% T3P in AcOEt solution (0.188 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane : AcOEt) to give the product. To a solution of the obtained product in AcOEt was added 4 N HCl-AcOEt. The reaction mixture was stirred at r.t. overnight. The resultant precipitate was collected by filtration, washed with AcOEt and dried to give 40 mg of (4-(3-(furan-3-yl)pyridin-2-yl)piperazin-1-yl)((2R,4S)-4-(6-methoxynaphthalen-2-yl)pyrrolidin-2-yl)methanone dihydrochloride.
Example 17: ((2R,4S)-4-Phenylpyrrolidin-2-yl)(4-(thieno[2,3-c]pyridin-7-yl)-3,6-dihydropyridin-1(2H)-yl)methanone
To a suspension of (2R,4S)-1-(tert-butoxycarbonyl)-4-phenylpyrrolidine-2-carboxylic acid (110 mg), 7-(1,2,3,6-tetrahydropyridin-4-yl)thieno[2,3-c]pyridine hydrochloride (131 m), WSC (94 mg) and HOBt (75 mg) in DMF (10 ml) was added DIPEA (0.330 ml). The reaction mixture was stirred for 4 days at r.t. The reaction mixture was diluted with water and stirred for a while. The resultant precipitate was collected by filtration and dried at r.t. overnight. The obtained crude mixture was purified by silica gel column chromatography (hexane : AcOEt) to give the product. To a solution of the obtained product in DCM (3 ml) was added TFA (1 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. The resultant residue was dissolved in water. The suspension was basified with sat. NaHCO3 aq. and extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered off and concentrated in vacuo to give 112 mg of ((2R,4S)-4-phenylpyrrolidin-2-yl)(4-(thieno[2,3-c]pyridin-7-yl)-3,6-dihydropyridin-1(2H)-yl)methanone.
Example 18: (4-(7-Chloroisoquinolin-1-yl)piperazin-1-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone dihydrochloride
The title compound was obtained by similar procedures to Example 5.
Example 19: ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(4-(3-methylthieno[2,3-c]pyridin-7-yl)piperazin-1-yl)methanone dihydrochloride
The title compound was obtained by similar procedures to Example 5.
Example 20: ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(4-(3-(furan-3-yl)-4-methylpyridin-2-yl)piperazin-1-yl)methanone hydrochloride
The title compound was obtained by similar procedures to Example 16.
Example 21: ((S)-3-((5-Methylthiazol-2-yl)methyl)pyrrolidin-1-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone hydrochloride
The title compound was obtained by similar procedures to Example 16.
Example 22: ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(5-hydroxy-6-(quinolin-2-ylmethyl)isoindolin-2-yl)methanone dihydrochloride
To a solution of ((2R,4S)-4-(3-chlorophenyl)pyrrolidin-2-yl)(5-methoxy-6-(quinolin-2-ylmethyl)isoindolin-2-yl)methanone (170 mg) in DCM (8.5 ml) cooled to 0°C was added BBr3 (1M in DCM) (1.707 ml). The reaction was stirred for 3 h. MeOH was added and the mixture was stirred at r.t. for 2 h. The solvents were removed by evaporation. The residue was diluted with H2O then basified with sat. NaHCO3 aq. The aqueous phase was extracted with AcOEt-MeOH. The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated. The residue was dissolved in MeOH/DCM (1/1) and treated with HCl (4M in AcOEt) (0.853 ml). The solvents were removed azeotroped with toluene. The residue was triturated in AcOEt, and the solids precipitated were collected by filtration. After drying in vacuo at 70°C overnight, ((2R,4S)-4-(3-chlorophenyl)pyrrolidin-2-yl)(5-hydroxy-6-(quinolin-2-ylmethyl)isoindolin-2-yl)methanone dihydrochloride (158 mg) was obtained.
Example 23: ((2R,4R)-4-(2-Ethylbutoxy)pyrrolidin-2-yl)(4-(3-(thiophen-2-yl)pyridin-2-yl)piperazin-1-yl)methanone hydrochloride
To a solution of (2R,4R)-1-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid (700 mg) and 1-(3-(thiophen-2-yl)pyridin-2-yl)piperazine dihydrochloride (1252 mg) in DCM (20 ml) were added TEA (2.11 ml) followed by 50% T3P in AcOEt solution (2.70 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. The resultant residue was purified by silica gel column chromatography (Hexane/AcOEt) to give the product. To a solution of the obtained product (92 mg) in DMF (3 ml) were added NaH (9.63 mg) and 3-bromomethylpentane (0.034 ml). The reaction mixture was stirred at 80°C for 3 h. After cooling to r.t., the reaction mixture was diluted with water and extracted with AcOEt. The combined organic layers were evaporated in vacuo. The resultant residue was purified by silica gel column chromatography (Hexane:AcOEt) to give the product. To a solution of the obtained product in AcOEt was added 4 N HCl-AcOEt. The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. DCM-IPE was added and the resultant precipitate was collected by filtration and dried to give 10 mg of ((2R,4R)-4-(2-ethylbutoxy)pyrrolidin-2-yl)(4-(3-(thiophen-2-yl)pyridin-2-yl)piperazin-1-yl)methanone hydrochloride.
Example 24: (5-(2-((4-Chlorophenyl)amino)ethyl)isoindolin-2-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone dihydrochloride
The title compound was obtained by similar procedures to Example 16.
Example 25: 5-(Furan-3-yl)-6-(4-((2R,4S)-4-phenylpyrrolidine-2-carbonyl)piperazin-1-yl)pyridin-2(1H)-one
To a solution of (2R,4S)-1-(tert-butoxycarbonyl)-4-phenylpyrrolidine-2-carboxylic acid (227 mg) and 1-(3-(furan-3-yl)-6-methoxypyridin-2-yl)piperazine hydrochloride (300 mg) in DCM (5 ml) were added TEA (0.544 ml) followed by 50% T3P in AcOEt solution (0.697 ml). The reaction mixture was stirred at r.t. overnight. The volatiles were evaporated in vacuo. The resultant residue was purified by silica gel column chromatography (hexane:AcOEt) to give the product (385 mg). To a solution of the obtained product (227 mg) in CH3CN (1 ml) was added sodium iodide (38.4 mg). After being stirred for 30 min., TMS-Cl (0.033 ml) was added to the mixture and heated at 70°C for 8 h. After cooling to r.t., the mixture was purified by silica gel column chromatography (DCM : MeOH). The obtained solid was washed with hexane and dried to give 39 mg of 5-(furan-3-yl)-6-(4-((2R,4S)-4-phenylpyrrolidine-2-carbonyl)piperazin-1-yl)pyridin-2(1H)-one.
Example 26: 2,2'-(2-((2R,4S)-4-Phenylpyrrolidine-2-carbonyl)isoindoline-5,6-diyl)dibenzonitrile hydrochloride
The title compound was obtained by similar procedures to Example 16.
Example 27: ((2R,4S)-4-(3-Cyclopropylphenyl)pyrrolidin-2-yl)(4-(3-(furan-3-yl)pyridin-2-yl)piperazin-1-yl)methanone dihydrochloride
The title compound was obtained by similar procedures to Example 16.
Example 28: 2-(2-((2R,4S)-4-(3-Chlorophenyl)pyrrolidine-2-carbonyl)isoindolin-5-yl)-3-fluorobenzonitrile hydrochloride
The title compound was obtained by similar procedures to Example 16.
Example 29: 2-(2-((2R,4S)-4-(3-Chlorophenyl)pyrrolidine-2-carbonyl)isoindolin-5-yl)-4-methoxynicotinonitrile
The title compound was obtained by similar procedures to Example 16.
Example 30: (4-(3-(Furan-3-yl)pyridin-2-yl)piperazin-1-yl)((2R,4S)-4-(3-propylphenyl)pyrrolidin-2-yl)methanone hydrochloride
The title compound was obtained by similar procedures to Example 16.
Example 31: (4-(3-(Furan-3-yl)pyridin-2-yl)piperazin-1-yl)((2R,4S)-4-(3-(trifluoromethyl)phenyl)pyrrolidin-2-yl)methanone hydrochloride
The title compound was obtained by similar procedures to Example 16.
Example 32: ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(4-(6-chloroquinolin-4-yl)piperazin-1-yl)methanone dihydrochloride
The title compound was obtained by similar procedures to Example 5.
Example 33: N-(6-Methoxy-2-((2R,4S)-4-phenylpyrrolidine-2-carbonyl)isoindolin-5-yl)-2-(4-methoxyphenyl)acetamide hydrochloride
A mixture of tert-butyl (2R,4S)-2-(5-bromo-6-methoxyisoindoline-2-carbonyl)-4-phenylpyrrolidine-1-carboxylate (200 mg), t-Bu-BrettPhos Pd G3 (34.1 mg), potassium orthophosphate (254 mg) and 2-(4-Methoxyphenyl)acetamide (198 mg) in t-BuOH (4 ml) was heated at 80°C for 4 h under N2 atmosphere. After cooling to r.t., the reaction mixture was diluted with H2O and extracted with AcOEt. The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated. The residue was triturated in AcOEt and the solids precipitated was removed by filtration. Purification via amino silica gel column chromatography (Hexane : AcOEt) afforded the product. To a solution of the obtained product in AcOEt (2 ml) was added 4 N HCl in AcOEt (2 ml). The reaction mixture was stirred at r.t. overnight. The solvent was removed by evaporation azeotroped with toluene. The residue was triturated in AcOEt and the solids precipitated were collected by filtration. After drying in vacuo at 70°C for 4h, N-(6-methoxy-2-((2R,4S)-4-phenylpyrrolidine-2-carbonyl)isoindolin-5-yl)-2-(4-methoxyphenyl)acetamide hydrochloride (66 mg) was obtained.
Example 34: ((2R,4S)-4-(3-Chlorophenyl)pyrrolidin-2-yl)(4-(naphthalen-1-yl)piperazin-1-yl)methanone hydrochloride
The title compound was obtained by similar procedures to Example 5.
Example 35: (4-(2-(Furan-3-yl)phenyl)piperazin-1-yl)((2R,4S)-4-(6-methoxynaphthalen-2-yl)pyrrolidin-2-yl)methanone hydrochloride
The title compound was obtained by similar procedures to Example 16.
Example 36: N-(6-((3S,5R)-5-(Isoindoline-2-carbonyl)pyrrolidin-3-yl)naphthalen-2-yl)acetamide hydrochloride
A mixture of tert-butyl (R)-2-(isoindoline-2-carbonyl)-4-(((trifluoromethyl)sulfonyl)oxy)-2,5-dihydro-1H-pyrrole-1-carboxylate (523 mg), N-(6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)naphthalen-2-yl)acetamide (458 mg), 2 M Na2CO3 aq. (1.696 ml) and Pd(Ph3P)4 (32.7 mg) in dioxane (8 ml) was stirred at r.t. overnight. The reaction mixture was diluted with water and extracted by AcOEt. The combined organic layers were washed with brine, dried over MgSO4, filtered off and concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (Hexane:AcOEt) to give the product. The obtained product was dissolved in EtOH (10 ml) and Pd/C (100 mg) was added under N2 atmosphere. The suspension was stirred at r.t. for 4 h under H2 atmosphere. Then, the reaction mixture was filtered through Celite. The filtrate was concentrated in vacuo. The resultant residue was purified by amino silica gel column chromatography (Hexane:AcOEt) to give the product. To a solution of the obtained product in AcOEt (5 mL) was added 4N HCl-AcOEt (5 mL). After being stirred at r.t. overnight, the resultant precipitate was collected by filtration and dried to give 62 mg of N-(6-((3S,5R)-5-(isoindoline-2-carbonyl)pyrrolidin-3-yl)naphthalen-2-yl)acetamide hydrochloride.
Example 37: (4-(3-(1H-Pyrrol-2-yl)pyridin-2-yl)piperazin-1-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone dihydrochloride
To a solution of (2R,4S)-1-(tert-butoxycarbonyl)-4-phenylpyrrolidine-2-carboxylic acid (510 mg), 1-(3-bromopyridin-2-yl)piperazine (509 mg) and TEA (1.220 ml) in DCM (10 ml) was added 50% T3P in AcOEt (1.563 ml). After being stirred at r.t. overnight, the volatiles were evaporated in vacuo. The resultant residue was purified by silica gel column chromatography (Hexane : AcOEt) to give 823 mg of the product. A mixture of the obtained product (160 mg), N-Boc-2-pyrroleboronic acid (131 mg), 2M Na2CO3 aq. (0.466 ml) and 1,1'-Bis(diphenylphosphino)ferrocene-palladium (II) dichloride dichloromethane complex (12.67 mg) in THF (3 ml) was heated at reflux overnight under N2 atmosphere. After cooling to r.t., the mixture was purified by silica gel column chromatography (Hexane : AcOEt) to give the product. To a solution of the obtained product in AcOEt was added 4N HCl-AcOEt. The reaction mixture was stirred at r.t. overnight. The resultant precipitate was collected by filtration and dried to give 15 mg of (4-(3-(1H-pyrrol-2-yl)pyridin-2-yl)piperazin-1-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone dihydrochloride.
Example 38: (4-(3-(Furan-3-yl)pyrazin-2-yl)piperazin-1-yl)((2R,4S)-4-phenylpyrrolidin-2-yl)methanone hydrochloride
The title compound was obtained by similar procedures to Example 16.
Example 39: N-(6-((3S,5R)-5-(Isoindoline-2-carbonyl)pyrrolidin-3-yl)quinolin-2-yl)acetamide
The title compound was obtained by similar procedures to Example 36.
Structures, physicochemical data, and preparations for Reference Example compounds and Example compounds prepared in accordance with the above methods are shown in the following tables.
Figure JPOXMLDOC01-appb-T000046
Figure JPOXMLDOC01-appb-T000047
Figure JPOXMLDOC01-appb-T000048
Figure JPOXMLDOC01-appb-T000049
Figure JPOXMLDOC01-appb-T000050
Figure JPOXMLDOC01-appb-T000051
Figure JPOXMLDOC01-appb-T000052
Figure JPOXMLDOC01-appb-T000053
Figure JPOXMLDOC01-appb-T000054
Figure JPOXMLDOC01-appb-T000055
Figure JPOXMLDOC01-appb-T000056
Figure JPOXMLDOC01-appb-T000057
Figure JPOXMLDOC01-appb-T000058
Test Examples
The following tests were conducted on Example compounds.
Test Example 1: HDAC2 enzyme assay (in vitro)
HDAC2 inhibition activity was performed according to the protocol of HDAC assay kits (purchased from BPS Bioscience). HDAC Assay Buffer (BPS catalog number 50031), HDAC Developer (BPS catalog number 50030), and HDAC Substrate (BPS number 50037) were used in this experiment.
Compounds for testing were diluted in DMSO to 100 fold the final concentration (100, 30, 10, 3, 1, 0.3, 0.1, 0.03, 0.01, 0 μM) dilution series was made in triplicate. The compounds were diluted in HDAC Assay Buffer to 5 fold their final concentration. The HDAC enzymes were diluted to 5 fold their final concentration in HDAC Assay Buffer on ice. The HDAC substrate were diluted in HDAC Assay Buffer at 5 fold their final concentration. The final enzyme concentration used in these assays were 0.2 ng/ml (HDAC2). Ten μL of compound and 20 μL of HDAC buffer, 10 μL of enzyme and 10 μL of substrate were mixed and incubated together in U96-well black plate (Thermo Scientific) in triplicate at room temperature for 2 hours. Fifty μL of HDAC developer solution was mixed and incubated at room temperature for 30 minutes. The fluorescence (355 nm, Emission: 430 nm) was measured by SpectraMax M2e, SoftMax(R) Pro (Molecular Devices). The IC50 was determined using Graph Pad Prims by a four parameter curve fit.
IC50 < 1 μM: ***; 1 μM < IC50 < 10 μM: **; 10 μM < IC50 < 30 μM: *
Figure JPOXMLDOC01-appb-T000059
Test Example 2: Cell culture and Purification of histone protein from the cell
SK-N-SH (Human Neuroblastoma) was used in this experiment. The cell line was purchased from the American Type Culture Collection. SK-N-SH was grown in DMEM media (Gibco) supplemented with 10% FBS (Gibco), 1% Glutamine and 1% P/S (Gibco). One hundred thousand of SK-N-SH cells were seeded in each well on 6-well plates, 24 hours after seeding, cells were treated with vehicle control (0 μM), 3 μM and 10 μM of a test compound which were diluted with DMEM and DMSO to achieve the desired final drug concentration and 0.1% final concentration of DMSO. After 48 hours treatment, cells were rinsed twice with ice-cold PBS and added 1 ml of TEB (Triton Extraction Buffer: PBS containing 0.5% Triton X 100 (v/v), 2 mM phenylmethylsulfonyl fluoride (PMSF), 0.02% (w/v) NaN3). The cell was lysed on ice for 30 minutes with gentle stirring and centrifuged to spin down the nuclei. The supernatant was remove and discard. The pellet was washed by TEB twice. Two hundreds μL of 0.2 N HCl was added to the samples and rotate at 4°C for 2 hours. The sample was centrifuged with max speed for 15 min and the supernatant was collected in another tube and neutralize with using 1N NaOH. This sample was used to the immunochemical detection.
Test Example 3: Oral administration, sampling of blood and brain
All mice were maintained in a 12-h light/dark cycle at 23 ± 2°C with free access to water and standard mouse chow.
Male C57BL/6 mice (purchased from Charles River Laboratories Japan) were fasted overnight. Screening compounds were dissolved in 5% arabic gum in water for pharmacokinetic (PK) study. Two animals per experimental arm administrated the compounds solution by oral gavage. Blood was collected via retro orbital puncture into K2EDTA tubes at 0 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 6 hours and 24 hours after dosing from a mouse. The brains were harvested after anesthetization at 0 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 6 hours and 24 hours after dosing from a mouse. The blood was centrifuged at 2,000 g for 5 minute at 4°C to obtain plasma.
The brain which was orally administrated a test compound at 100 mg/Kg dose at 0, 2 hours, 4 hours and 6 hours to male C57BL/6 mice (n=5) was divided into two hemispheres. One of the hemispheres was used for pharmacokinetic study and the other was used for testing to determine the level of histone acetylation (ex vivo study).
Test Example 4: Pharmacokinetic study
1.1 Determination of Compound in Mouse Plasma and Brain Homogenates
The compound in mouse plasma and brain homogenates was quantified with the high-performance liquid chromatographic-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method.
1.1.1 Preparation of Standard Solutions
The compound was dissolved in dimethylsulfoxide (DMSO) at 1 mg/mL. This solution was diluted with methanol to prepare the standard solutions at 0.05 to 50 μg/mL.
1.1.2 Preparation of Spiked Samples for Calibration Curve and Quality Control
Into 1.2-mL polypropylene tubes in an ice-water bath, 0.05 mL of the ice-cold blank plasma (or the ice-cold blank brain homogenates) and 10 μL of the standard solution were added. The concentrations of calibration curve samples were 0.01 to 10 μg/mL (C1 to C7, n = 1 each), and those of quality control (QC) samples were 0.03, 5, and 8 μg/mL (n = 2 each).
1.1.3 Preparation of Measurement Samples
The measurement samples (0.05 mL) in 1.2-mL polypropylene tubes were thawed in a water bath, and then transferred immediately to an ice-water bath. Into the tubes in an ice-water bath, 10 μL of methanol were added.
1.1.4 Sample Preparation for Analysis
To each sample in an ice-water bath, 10 μL of the internal standard (IS) solution (spiperone: 500 ng/mL) and 0.5 mL of methanol were added and mixed. The mixture was centrifuged at 6130 g for 10 minutes at 10°C or below to obtain the supernatant. The supernatant (0.1 mL) was mixed with 0.5 mL of water/acetonitrile (1:1, v/v) followed by the LC-MS/MS analysis.
1.1.5 Apparatus
High-performance liquid chromatography (HPLC) analysis was carried out with the Prominence UFLC system (Model LC-20AD pumps, Model SIL-20ACHT autosampler, Model CTO-20AC column oven, Model DGU-20A5 degasser, Model FCV-12AH switching valve, and Model CBM-20A system controller [Shimadzu Corp]).
Tandem mass spectrometry (MS/MS) analysis was carried out with the 4000QTRAP LC/MS/MS system (AB SCIEX) equipped with an ESI source and a switching valve (Valco Instruments Co Inc).
1.1.6 Analytical Conditions
Chromatographic separation was achieved on an XBridge C18 (3.5 μm, 2.1 mmID x 50 mm, Waters Corp). A binary gradient was formed with solvents A; 10 mmol/L ammonium acetate aqueous solution and B; acetonitrile at a flow rate of 0.55 mL/min. The ionization method was electrospray ionization with a positive mode. Multiple reaction monitoring mode utilizing the precursor and product ions of the analyte and internal standard described below was employed.
Figure JPOXMLDOC01-appb-T000060
 1.1.7 Calibration Curves and Calculations
The peak-area ratios of the analyte to the IS in the calibration curve samples were obtained. The quadratic regression equation (Y = aX2 + bX + c, weight: 1/X2) was calculated by the least square method using the peak-area ratios (Y) and the spiked concentrations (X). The concentrations of the analyte in the samples were determined by substituting the obtained peak-area ratios into the above equations. Analyst version 1.5.1 (AB SCIEX) was used for the construction of the calibration curve, and the determination of peak areas and concentrations.
1.2 Data Processing
The mean and standard deviation of concentration at each time point, and the concentration ratio of brain to plasma (Kp) were calculated with Microsoft Excel 2010 (Microsoft Corp). Brain concentrations were corrected with dilution factor (4-time dilution) of brain homogenates. The pharmacokinetic parameters (Cmax, T1/2, AUCinf) were calculated with the aid of non-compartmental model, Phoenix WinNonlin version 6.4 (Pharsight Corp).
1.3 Results
Results are shown as follows. The tested compounds EX11 and EX19 showed good plasma and brain exposure when dosed orally at 30 and 100 mg/kg as seen in the following table.
Figure JPOXMLDOC01-appb-T000061
Test Example 5: Purification of histone protein from the mouse brain
The brain of mice (approximately 100 μg) obtained in Test Example 3 was homogenized in 1 ml of TEB into a 1.5 mL tube with 21G syringe repeatedly passed through and then an ultrasonic Homogenizer for 1 minute. The sample was incubated on ice and centrifuged with max speed for 15 min. The cell was lysed on ice for 10 minutes with gentle stirring and centrifuged to spin down the nuclei. The supernatant was remove and discard. The pellet was washed by TEB. The supernatant was removed and added 200 μL of 0.2 N HCl and rotate at 4°C for 2 hours. The sample was centrifuged with max speed for 15 min and the supernatant was collected in another tube and neutralize with using 1 N NaOH. This sample was used to the immunochemical detection.
Test Example 6: Immunochemical detection of the level of Histone acetylation
The concentration of protein in each supernatant obtained in Test Example 2 and Test Example 5 was determined by using the BCA kit (Thermo Fisher Science, Rockfield, IL). Equal amounts of samples (10 μg protein) were electropheretically separated in 10-20% gradient acrylamide gels (Wako, Japan) and then transferred to PVDF membranes. The membranes were then blotted with a mouse monoclonal antibody against acetyl-H4(Lys12) (Merck KGaA, Darmstadt, Germany), a mouse monoclonal antibody against acetyl-H3(Lys9) (Merck KGaA, Darmstadt, Germany) or a mouse monoclonal antibody against actin (MILLIPORE, Billerica, MA). HRP-conjugated secondary antibodies (MILLIPORE, Billerica, MA) were used and detected by using ECL kit (Merck KGaA, Darmstadt, Germany). The band intensity was measured with Image Analysis Software Quantity One (BIO-RAD, Hercules, CA). The statistical difference was assessed by Student’s t-test or Dunnett test.
The results by the treatment of EX11 as a test compound are shown as follows.
Histone H4K12 acetylation levels in SKNSH cells were increased by the treatment of EX11 with statistical significance at 3 μM and 10 μM compared to vehicle control (p<0.05) in a concentration response manner (Fig. 1).
Histone H3K9 acetylation levels in SKNSH cells were increased by the treatment of EX11 with statistical significance at 3 μM and 10 μM compared to vehicle control (p<0.05) in a concentration response manner (Fig. 2).
These results demonstrate the HDAC2 inhibition activity of the test compound (EX11) in the cells.
Lower concentration of the EX11 treatment than that of brain Cmax could significantly increase in histone acetylation (H4K12 and H3K9) level of human neuroblastoma (SKNSH) cell.
In addition to the cell based assay results, we tested an ex vivo study (H4K12 Level of histone acetylation in mice brain) as described above. After an oral administration of EX11 (100 mg/kg EX11) as a test compound to mice, the brain was picked out at 2, 4, and 6 hours. The amount of histone acetylation was evaluated as above (n = 5).
Histone H4K12 acetylation levels were increased by the treatment of EX11 in mouse brain at 4 hours after 100 mg/kg dosing with statistical significance compared to the vehicle control (p<0.05). The results demonstrate that EX11 has an HDAC2 inhibition activity as well as good brain penetration (Fig. 3).
A compound of Formula [I], or a pharmaceutically acceptable salt thereof, has an HDAC inhibition activity, and is expected to be used as a medicament for treatment and/or prevention of diseases involving HDACs.

Claims (16)

  1. A compound of Formula [I]:
    Figure JPOXMLDOC01-appb-C000001
     or a salt thereof,
    wherein R1 is
    1) an optionally substituted 6- to 10-membered aryl,
    2) an optionally substituted 5- to 10-membered heteroaryl, provided that when the heteroaryl is a tetrazolyl, the tetrazolyl should bind to the pyrrolidine ring via its carbon atom, or
    3) -O-C4-10 alkyl;
    a ring structure A of the following formula:
    Figure JPOXMLDOC01-appb-C000002
     is any one of the following formulae (A1) to (A3):
    Figure JPOXMLDOC01-appb-C000003
     wherein ring groups G1 and G2 of the following formulae:
    Figure JPOXMLDOC01-appb-C000004
     are each independently 6- to 10-membered aryl or 5- to 10-membered heteroaryl, which is optionally substituted with oxo;
    X1 is N, CH, or C;
    the following structure:
    Figure JPOXMLDOC01-appb-C000005
     in the formula (A1) is a bond, wherein:
    1) when X1 is N, then the bond is a single bond,
    2) when X1 is CH, then the bond is a single bond, and
    3) when X1 is C, then the bond is a double bond;
    m and n are each independently an integer of 1 or 2;
    R21, R22, and R23 are each independent, each of which is independent when existing plurally, and are:
    1) C1-6 alkyl, C2-6 alkenyl, C3-6 cycloalkyl, 6- to 10-membered aryl, 5- to 10-membered mono- or bi-cyclic heteroaryl, or -NH-C(=O)-C1-6 alkyl, wherein these groups are optionally substituted,
    2) -OR24, wherein R24 is hydrogen or an optionally substituted C1-6 alkyl,
    3) halogen, or
    4) cyano;
    p, q, and r are each independently an integer of 0 to 2; and
    a wavy line is a binding site.
  2. The compound according to claim 1, or a salt thereof, wherein R1 is:
    1) 6- to 10-membered aryl or 5- to 10-membered heteroaryl, which is optionally substituted with 1 to 3 groups independently selected from the group consisting of the following groups 1-1) to 1-8):
    1-1) C1-6 alkyl,
    1-2) halo-C1-6 alkyl,
    1-3) C3-6 cycloalkyl,
    1-4) -OR11, wherein R11 is hydrogen or C1-6 alkyl,
    1-5) -NH-C(=O)-C1-6 alkyl,
    1-6) -C(=O)-NH-C1-6 alkyl,
    1-7) halogen, and
    1-8) 5- to 10-membered heterocyclyl optionally substituted with oxo, or
    2) -O-C4-10 alkyl.
  3. The compound of according to claim 1 or 2, or a salt thereof, wherein ring groups G1 and G2 are each independently any one of the following ring groups:
    Figure JPOXMLDOC01-appb-C000006
     wherein X21, X22, X31, X32, X41, X42, and X51 are each independently N or CH, and
    X61 is NH or O.
  4. The compound according to any one of claims 1 to 3, or a salt thereof, wherein ring groups G1 and G2 are each independently any one of the following ring groups.
    Figure JPOXMLDOC01-appb-C000007
  5. The compound according to any one of claims 1 to 4, or a salt thereof, wherein R21, R22, and R23 are each independent, each of which is independent when existing plurally, and are:
    1) C1-6 alkyl, C2-6 alkenyl, C3-6 cycloalkyl, 6- to 10-membered aryl, 5- to 10-membered mono- or bi-cyclic heteroaryl, or -NH-C(=O)-C1-6 alkyl,
    2) -OR24, wherein R24 is hydrogen or C1-6 alkyl,
    3) halogen, or
    4) cyano; wherein
    each group in the above group 1) and the C1-6 alkyl in the above group 2) may be optionally substituted with 1 to 3 substituents independently selected from the group consisting of the following groups 2-1) to 2-7):
    2-1) halogen,
    2-2) cyano,
    2-3) -O-C1-6 alkyl,
    2-4) an optionally substituted 5- to 10-membered heteroaryl,
    2-5) an optionally substituted 6- to 10-membered aryl,
    2-6) an optionally substituted -C(=O)-NH-(6- to 10-membered aryl), and
    2-7) an optionally substituted -NH-(6- to 10-membered aryl).
  6. The compound according to any one of claims 1 to 5, or a salt thereof, wherein R21, R22, and R23 are each independent, each of which is independent when existing plurally, and are:
    1) C1-6 alkyl optionally substituted with 1 to 3 substituents independently selected from the group consisting of halogen, an optionally substituted 5- to 10-membered heteroaryl, an optionally substituted 6- to 10-membered aryl, an optionally substituted -C(=O)-NH-(6- to 10-membered aryl), and an optionally substituted -NH-(6- to 10-membered aryl),
    2) C2-6 alkenyl,
    3) C3-6 cycloalkyl,
    4) -O-C1-6 alkyl,
    5) 6- to 10-membered aryl optionally substituted with 1 to 3 substituents independently selected from the group consisting of halogen and cyano,
    6) 5- to 10-membered mono- or bi-cyclic heteroaryl optionally substituted with 1 or 2 substituents independently selected from the group consisting of cyano and -O-C1-6 alkyl,
    7) -NH-C(=O)-C1-6 alkyl optionally substituted with an optionally substituted 6- to 10-membered aryl or an optionally substituted 5- to 10-membered heteroaryl,
    8) hydroxy,
    9) halogen, or
    10) cyano.
  7. The compound according to claim 1, or a salt thereof, selected from the group consisting of the following compounds:
    Figure JPOXMLDOC01-appb-C000008
    Figure JPOXMLDOC01-appb-C000009
  8. The compound according to claim 1, selected from the group consisting of the following compounds or salts:
    Figure JPOXMLDOC01-appb-C000010
    Figure JPOXMLDOC01-appb-C000011
  9. A pharmaceutical composition comprising a compound according to any one of claims 1 to 8, or a salt thereof, and a pharmaceutically acceptable carrier.
  10. The composition according to claim 9, for use in treatment or prevention of a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
  11. A medicament for use in treatment or prevention of a disease involving HDAC, comprising a compound according to any one of claims 1 to 8, or a salt thereof.
  12. The medicament according to claim 11, wherein the disease is selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
  13. A compound according to any one of claims 1 to 8, or a salt thereof, for use in treatment or prevention of a disease involving HDAC.
  14. A compound according to any one of claims 1 to 8, or a salt thereof, for use in treatment or prevention of a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
  15. Use of a compound according to any one of claims 1 to 8, or a salt thereof, or a pharmaceutical composition according to claim 9 in the manufacture of a medicament for use in treatment or prevention of a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy.
  16. A method of treating or preventing a disease selected from the group consisting of central nervous system disease, cerebral infarction, spinal cord injury, cerebral tumor, pain, and hereditary neuropathy in a subject in need thereof, comprising administering a therapeutically effective amount of a compound according to any one of claims 1 to 8, or a salt thereof, or a pharmaceutical composition according to claim 9 to the subject.
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