Calpain inhibitor

Abstract

The present invention provides a calpain inhibitor that has excellent calpain inhibitive capacity. The present invention provides a compound represented by general formula (I), or a salt thereof. (In formula (I), R1 represents a hydrogen atom, an alkyl group that may be substituted, or the like, or may be bonded with R2 to form a ring; R2 and R3 each independently represent a hydrogen atom or the like, or R2 and R3 may be bonded to form a ring, provided that when R2 and R1 are bonded to form a ring including a double bond, R3 may not exist; R4 represents a hydrogen atom, an alkyl group that may be substituted, or the like; R5 represents a hydrogen atom, an alkyl group that may be substituted, or the like; R6 represents a halogen, a cycloalkyl group that may be substituted, or the like; X represents O or S; when R1 and R2 are bonded to form a ring, R1 may represent O, S, or N, and R2 may represent O or S; and L represents an amide bond.)

Description

Calpain inhibitors

[0001] The present invention relates to a compound having calpain inhibitory activity, a calpain inhibitor containing the compound, and a pharmaceutical composition. The present invention also relates to a method for preventing or treating a disease associated with calpain activity using the compound.

[0002] Calpain is a Ca ２＋ Calpain is a cysteine ​​protease that is activated dependently on the ATP-dependent pathway and is a modulator molecule that regulates the function and structure of substrate proteins by limited cleavage. While calpain is involved in various biological phenomena, its activity and pathogenic mutations in its genes have been reported to be associated with various diseases, including neurodegenerative diseases, cardiomuscular diseases, ischemic diseases, cancer, and eye diseases. Furthermore, there are infectious diseases in which calpain is essential for the infection and survival of viruses and pathogens. For example, calpain is known to be associated with COVID-19 caused by SARS-CoV-2 or its mutant strains, malaria, trypanosomiasis, and schistosomiasis. Therefore, calpain inhibitors that inhibit calpain activity are considered useful for the treatment or prevention of calpain-related diseases.

[0003] Various calpain inhibitors have been reported so far. For example, Patent Document 1 discloses an α-ketoamide derivative, which is described as having calpain inhibitory activity and excellent tissue transferability and oral absorbability.

[0004] Japanese Patent Application Laid-Open No. 2006-76989

[0005] In consideration of application to the treatment or prevention of calpain-associated diseases, there remains a demand for calpain inhibitors with higher calpain inhibitory potency. Therefore, an object of the present invention is to provide a calpain inhibitor with excellent calpain inhibitory potency.

[0006] The present inventors have found that calpain inhibitory activity can be improved by using an α-ketoamide derivative of the peptide disclosed in Patent Document 1 as a basic skeleton and binding an amide group having an α-carbon bonded to an oxygen atom or a sulfur atom to the N-terminus of the peptide.

[0007] The present invention relates to a compound represented by the following general formula (I) or a salt thereof: (In formula (I), R １ represents a hydrogen atom; an optionally substituted linear, branched, or cyclic alkyl group; an optionally substituted linear or branched alkenyl group; an optionally substituted linear or branched alkynyl group; an optionally substituted aryl group; or an optionally substituted heterocyclic group, or R ２ may be bonded to form a ring, R ２ and R ３ each independently represents a hydrogen atom; a hydroxyl group; an optionally substituted alkoxy group; or an optionally substituted linear, branched, or cyclic alkyl group; or R ２ and R ３ may be bonded to form a ring, provided that R ２ is R １ When R is bonded to R to form a ring containing a double bond, ３ may not be present, and R ４ represents a hydrogen atom or an optionally substituted linear or branched alkyl group having 4 or more carbon atoms; R ５ represents a hydrogen atom; an optionally substituted linear or branched alkyl group; an optionally substituted linear or branched alkenyl group; an optionally substituted linear or branched alkynyl group; an optionally substituted aryl group; or an optionally substituted heterocyclic group; ６ represents an optionally substituted linear, branched or cyclic alkyl group; an optionally substituted linear or branched alkenyl group; an optionally substituted linear or branched alkynyl group; an optionally substituted aryl group; an optionally substituted heterocyclic group; an optionally substituted fused polycyclic hydrocarbon group; an optionally substituted alkoxy group; or a hydrogen atom; X represents O or S; R １ and R ２ When R １ may represent O, S, or N, R ２may represent O or S, L is an amide bond, an ester bond, -NH-, -N-(linear, branched or cyclic alkylene)-, or -(linear or branched alkylene-O-) ｎ -(n represents an integer of 1 to 10) or a single bond. The present invention also relates to a calpain inhibitor comprising the above compound or a salt thereof. The present invention also relates to a pharmaceutical composition for treating or preventing a disease associated with calpain activity, comprising the above compound or a salt thereof. The present invention also relates to a method for treating or preventing a disease associated with calpain activity, comprising administering an effective amount of the above compound or a salt thereof to an individual in need of such treatment or prevention.

[0008] According to an embodiment of the present invention, calpain inhibitory activity can be improved by using an α-ketoamide derivative of the peptide disclosed in Patent Document 1 as a basic skeleton and attaching an amide group having an α-carbon bonded to an oxygen atom or a sulfur atom to the N-terminus of the peptide, thereby providing a calpain inhibitor with improved calpain inhibitory activity. The reason for this effect is not intended to limit the present invention in any way and is not clear, but it is presumed to be due to improved reactivity with calpain.

[0009] 1 is a graph showing the results of measuring calpain activity, 2 is a graph showing the results of measuring calpain activity over time, and 3 is a graph showing the results of measuring calpain activity.

[0010] Hereinafter, embodiments of the present invention will be specifically described, but the present invention is not limited to these embodiments. Furthermore, the embodiments can be appropriately combined as long as the effects of the present invention can be obtained.

[0011] <Definition of Terms> In this specification, an "alkyl group" or an "alkyl" moiety in other groups means a linear, branched, or cyclic saturated hydrocarbon group, and unless otherwise specified, is preferably a saturated hydrocarbon group having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 1,2-dimethylpropyl group, Examples of the alkyl group include hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1-ethyl-2-methylpropyl, 1,1,2-trimethylpropyl, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. C1-5 alkyl groups are more preferred, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl, isobutyl, pentyl, isopentyl, and 2,3-dimethylpropyl. C1-3 alkyl groups are even more preferred, such as methyl, ethyl, n-propyl, and isopropyl, and most preferably methyl or ethyl. Furthermore, the term "alkylene group" refers to a divalent group obtained by removing one hydrogen atom from the above alkyl group.

[0012] The "alkoxy group" refers to a group bonded to the above-mentioned alkyl group via an oxygen atom ((alkyl)-O- group), and the alkyl group portion is as defined above. For example, the alkoxy group may have an alkyl group portion having 1 to 6 carbon atoms. Examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group, an n-butyloxy group, an isobutyloxy group, a sec-butyloxy group, a tert-butyloxy group, a pentyloxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, a 1-methylbutyloxy group, a 2-methylbutyloxy group, a 1,2-dimethylpropyloxy group, a hexyloxy group, a 1-methylpentyloxy group, a 2-methylpentyloxy group, a 3-methylpentyloxy group, a 4-methylpentyloxy group, a 1,1-dimethylbutyloxy group, a 1,2-dimethylbutyloxy group, a 1,3-dimethylbutyloxy group, a 2,2-dimethylbutyloxy group, a 2,3-dimethylbutyloxy group, a 3,3-dimethylbutyloxy group, a 1-ethylbutyloxy group, a 2-ethylbutyloxy group, a 1-ethyl-2-methylpropyloxy group, and a 1,1,2-trimethylpropyloxy group. The C1-6 alkoxy group is preferably a C1-5 alkoxy group, and more preferably a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group, an n-butyloxy group, a sec-butyloxy group, a t-butyloxy group, an isobutyloxy group, a pentyloxy group, an isopentyloxy group, or a 2,3-dimethylpropyloxy group.

[0013] An "alkenyl group" is a monovalent group obtained by removing one hydrogen atom from any carbon atom of a straight-chain, branched, or cyclic unsaturated hydrocarbon having one or more carbon-carbon double bonds, and may have, for example, 2 to 10, 2 to 6, or 2 to 4 carbon atoms. Examples of C2-10 alkenyl groups include vinyl, propenyl, isopropenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-methyl-1-butenyl, 1-methyl-2-butenyl, 1-methyl-3-butenyl, 1-methylidenebutyl, 2-methyl-1-butenyl, 2- Methyl-2-butenyl group, 2-methyl-3-butenyl group, 2-methylidenebutyl group, 3-methyl-1-butenyl group, 3-methyl-2-butenyl group, 3-methyl-3-butenyl group, 1-ethyl-1-propenyl group, 1-ethyl-2-propenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, 5-hexenyl group, 1-methyl-1-pentenyl group, 1- Methyl-2-pentenyl group, 1-methyl-3-pentenyl group, 1-methyl-4-pentenyl group, 1-methylidenepentyl group, 2-methyl-1-pentenyl group, 2-methyl-2-pentenyl group, 2-methyl-3-pentenyl group, 2-methyl-4-pentenyl group, 2-methylidenepentyl group, 3-methyl-1-pentenyl group, 3-methyl-2-pentenyl group, 3-methyl-3-pentenyl group Examples of such groups include 3-methyl-4-pentenyl, 3-methylidenepentyl, 4-methyl-1-pentenyl, 4-methyl-2-pentenyl, 4-methyl-3-pentenyl, 4-methyl-4-pentenyl, 1-heptenyl, 2-heptenyl, 3-heptenyl, 4-heptenyl, 5-heptenyl, 6-heptenyl, octenyl, nonenyl, and decenyl groups.

[0014] An "alkynyl group" is a monovalent group obtained by removing one hydrogen atom from any carbon atom of a straight-chain or branched unsaturated hydrocarbon having one or more carbon-carbon triple bonds, and may have, for example, 2 to 6 or 2 to 4 carbon atoms. Examples of the alkynyl group include an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, a 3-butynyl group, a pentynyl group, a hexynyl group, and a phenylethynyl group.

[0015] An "aryl group" is a monovalent aromatic hydrocarbon group which may have, for example, 6 to 10 carbon atoms and includes phenyl and naphthyl groups.

[0016] A "heterocyclic group" is a monovalent group containing at least one heteroatom selected from a nitrogen atom, an oxygen atom, and a sulfur atom, and preferably has 5 to 14 members. The heterocyclic group may be a monocyclic heterocyclic group or a fused heterocyclic group. The number of heteroatoms contained in a 5- to 14-membered heterocyclic group may be, for example, 1 to 5, 1 to 4, 1 to 3, 1 to 2, 2, or 1. For example, various combinations exist, such as a heterocyclic group containing one nitrogen atom, a heterocyclic group containing two nitrogen atoms, a heterocyclic group containing three nitrogen atoms, a heterocyclic group containing one oxygen atom, a heterocyclic group containing two oxygen atoms, a heterocyclic group containing one oxygen atom and one nitrogen atom, and a heterocyclic group containing one sulfur atom. The 5- to 14-membered heterocyclic group may be aromatic (heteroaryl group) or non-aromatic. The monocyclic heterocyclic group is preferably a 5- or 6-membered ring, and the fused heterocyclic group is preferably an 8- to 10-membered ring.Examples of 5- to 14-membered heterocyclic groups include piperidyl, piperazyl, morpholyl, quinuclidyl, pyrrolidinyl, azetidyl, oxetyl, azetidin-2-one-yl, aziridinyl, tropanyl, furyl, tetrahydrofuryl, thienyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, dioxolanyl, oxazolyl, oxazolinyl, isoxazolyl, thiazolyl, thiazolinyl, isothiazolyl, imidazolyl, imidazolinyl, imidazolidinyl, and oxazolidinyl. , isoxazolidinyl, thiazolidinyl, pyrazolyl, pyrazolinyl, pyrazolidinyl, oxadiazolyl, furazanyl, thiadiazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, tetrazolyl, pyranyl, pyridyl, piperidinyl, pyridazinyl, pyrimidinyl, pyrazinyl, piperazinyl, dioxanyl, oxazinyl, morpholinyl, thiomorpholinyl, thiazinyl, triazinyl, benzofuranyl, isobenzofuranyl, dihydrobenzofuranyl , dihydroisobenzofuranyl, benzothienyl, isobenzothienyl, dihydrobenzothienyl, dihydroisobenzothienyl, tetrahydrobenzothienyl, quinolyl, isoquinolyl, quinazolinyl, phthalazinyl, pteridinyl, coumaryl, chromonyl, 1,4-benzodiazepinyl, indolyl, isoindolyl, benzimidazolyl, benzofuryl, purinyl, acridinyl, phenoxazinyl, phenothiazinyl, benzoxazolyl, benzothiazolyl, Examples include benzodioxanyl, benzimidazolyl, benzimidazolyl, benzodioxolanyl, benzodioxanylchromenyl, chromanyl, isochromanyl, chromanonyl, cinnolinyl, quinoxalinyl, indolizinyl, quinolidinyl, imidazopyridyl, naphthyridinyl, dihydrobenzoxazinyl, dihydrobenzoxazolinonyl, dihydrobenzoxazinonyl, benzothioxanyl, tetrahydrofuranyl, tetrahydropyranyl, and tetrahydrothiophenyl.

[0017] As used herein, the term "halogen atom" refers to a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and is preferably a fluorine atom, a chlorine atom, or a bromine atom, and more preferably a fluorine atom or a chlorine atom. As used herein, the term "carboxyl group" refers to a group represented by -C(=O)-OH.

[0018] Throughout this specification, substituents on alkyl groups or alkyl moieties, alkenyl groups, or alkynyl groups generally include halogen atoms, hydroxyl groups, amino groups, alkylamino groups, dialkylamino groups, thiol groups, alkylthiol groups, sulfinyl groups, sulfonyl groups, thioalkyl groups, alkoxy groups, cyclic ethers, carboxyl groups, alkylcarbonyl groups, alkoxycarbonyl groups, alkoxycarbonylamino groups, alkylcarbonyloxy groups, alkylaminocarbonyl groups, alkylcarbonylamino groups, carbonylamino groups, hydrazinyl groups, cycloalkyl groups, and the like. When an alkyl group or alkyl moiety, alkenyl group, or alkynyl group is substituted, the number of such substituents can be, for example, 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2, 1, 2, or 3. Examples of substituents with which an aryl group or heterocyclic group may be substituted include halogen atoms and alkoxy groups. When an aryl group or heterocyclic group is substituted, the number of the substituents can be, for example, 1 to 5, 1, 2, or 3.

[0019] <Compound Represented by General Formula (I)> In one aspect, the present invention relates to a compound represented by the following general formula (I) (hereinafter, may be referred to as compound (I)) or a salt thereof: (In formula (I), R １ represents a hydrogen atom; an optionally substituted linear, branched, or cyclic alkyl group; an optionally substituted linear or branched alkenyl group; an optionally substituted linear or branched alkynyl group; an optionally substituted aryl group; or an optionally substituted heterocyclic group, or R ２ may be bonded to form a ring, R ２ and R ３each independently represents a hydrogen atom; a hydroxyl group; an optionally substituted alkoxy group; or an optionally substituted linear, branched, or cyclic alkyl group; or R ２ and R ３ may be bonded to form a ring, provided that R ２ is R １ When R is bonded to R to form a ring containing a double bond, ３ may not be present, and R ４ represents a hydrogen atom or an optionally substituted linear or branched alkyl group having 4 or more carbon atoms; R ５ represents a hydrogen atom; an optionally substituted linear or branched alkyl group; an optionally substituted linear or branched alkenyl group; an optionally substituted linear or branched alkynyl group; an optionally substituted aryl group; or an optionally substituted heterocyclic group; ６ represents an optionally substituted linear, branched or cyclic alkyl group; an optionally substituted linear or branched alkenyl group; an optionally substituted linear or branched alkynyl group; an optionally substituted aryl group; an optionally substituted heterocyclic group; an optionally substituted fused polycyclic hydrocarbon group; an optionally substituted alkoxy group; or a hydrogen atom; X represents O or S; R １ and R ２ When R １ may represent O, S, or N, R ２ may represent O or S, L is an amide bond, an ester bond, -NH-, -N-(linear, branched or cyclic alkylene)-, or -(linear or branched alkylene-O-) ｎ - (n is an integer of 1 to 10) or a single bond.

[0020] R １is preferably a hydrogen atom or an optionally substituted linear, branched, or cyclic alkyl group, more preferably a hydrogen atom or a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms which may be substituted with one or more groups selected from a hydroxyl group, a carboxyl group, a cycloether, an alkoxy group (e.g., a methoxy group, an ethoxy group), a sulfonyl group, a halogen atom, an amino group, a methylamino group, and a dimethylamino group, and even more preferably a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group) which may be substituted with one or more groups selected from a hydroxyl group, a carboxyl group, a cycloether, an alkoxy group (e.g., a methoxy group, an ethoxy group), a sulfonyl group, a halogen atom, an amino group, a methylamino group, and a dimethylamino group. Alternatively, R １ is preferably R ２ can combine with R to form a 3- to 8-membered heterocyclic ring containing one or two oxygen and / or sulfur atoms. １ and R ２ When R １ and R ２ may each independently be O, S, or N. １ and R ２ The heterocyclic ring formed by bonding may further contain a nitrogen atom. The heterocyclic ring is as described above for the heterocyclic group, and may be, for example, oxolanyl, oxanyl, dioxolanyl, dioxanyl, thiolanyl, thianyl, oxathiolanyl, dithiolanyl, dithianyl, oxazolidinyl, isoxazolidinyl, thiazolidinyl, or isothiazolidinyl. R １ and R ２ The heterocycle formed by bonding may be substituted. Examples of the substituent include a halogen atom, an alkyl group (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group), an alkoxy group (e.g., a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group), and a cyano group.

[0021] R ２is preferably a hydrogen atom, an alkyl group, or an alkoxy group, and more preferably a hydrogen atom, a methyl group, or a methoxy group.

[0022] R ３ is preferably a hydrogen atom, an alkyl group, or an alkoxy group, and more preferably a hydrogen atom, a methyl group, or a methoxy group.

[0023] Or, R ２ and R ３ are preferably linked together to form a cycloalkyl group, more preferably a C3-C5 cycloalkyl group.

[0024] L is preferably -(linear or branched alkylene-O-) ｎ - (n is an integer of 1 to 10) or a single bond. The straight-chain or branched alkylene may be, for example, an alkylene having 1 to 4 carbon atoms, preferably 2 or 3 carbon atoms, and more preferably 2 carbon atoms.

[0025] X is an oxygen atom (O) or a sulfur atom (S), and is preferably O.

[0026] For example, in the above formula (I), -XL-R １ The group represented by the formula (II) may be a group represented by the formula (II) below. (In formula (II), n represents an integer of 0 to 10.)

[0027] Furthermore, for example, in the above formula (I), -XL-R １ The group represented by may be a hydroxyl group, a thiol group, or a group selected from the following:

[0028]

[0029] As described above, in the formula (I), R １ and R ２ can be linked to form a ring. For example, The partial structure represented by the formula (wherein m is an integer of 1 to 3, and q is 0 or 1) may be a structure represented by the formula (wherein m is an integer of 1 to 3, and q is 0 or 1).

[0030] R １ and R ２The ring formed by bonding may be a ring containing a double bond. As described above, the ring containing a double bond may also be substituted with a substituent. The substituents are as described above. The ring containing a double bond is, for example, a 5-membered ring or a 6-membered ring. In the ring containing a double bond, when the α-carbon of the carbonyl group is involved in the formation of the double bond, R ３ does not exist. Examples of such a ring include an oxazole ring, an isoxazole ring, a furan ring, a thiophene ring, a pyran ring, a thiopyran ring, a thiazole ring, and an isothiazole ring. Therefore, for example, in the above formula (I), The partial structure represented by the following formula (R ７ are the same or different and represent a substituent bonded to the heterocycle, and P represents an integer of 0 to 3). R ７ Examples of the substituent represented by the formula (I) include a halogen atom, an alkyl group (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group), an alkoxy group (e.g., a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group), and a cyano group.

[0031] R ４ or R ５ Examples of the substituents with which the alkyl group or alkyl moiety, alkenyl group, or alkynyl group represented by the formula (I) may be substituted include aryl groups (e.g., phenyl, tolyl, and xylyl), heteroaryl groups (e.g., imidazoyl and indole groups), alkoxy groups (e.g., methoxy, ethoxy, n-propyloxy, and isopropyloxy), C1-3 thioalkyl groups, amino groups, guanidino groups, amido groups, thiol groups, carboxyl groups, hydroxyl groups, and C3-6 cycloalkyl groups. ５ Examples of the substituent with which the aryl group or heterocyclic group represented by the formula (I) may be substituted include a halogen atom, an alkyl group (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group), an alkoxy group (e.g., a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group), and the like.

[0032] In one embodiment, R ４ and R５ may each independently be a group corresponding to the side chain of an amino acid, for example, a group corresponding to the side chain of an amino acid selected from the group consisting of Met, Ser, Ala, Thr, Val, Tyr, Leu, Asn, Ile, Gln, Asp, Phe, Glu, Trp, Lys, Cys, Arg, His, Gly (all of which are represented by the three-letter code for amino acids), norleucine (Nle), and methionine sulfoxide (MetO) (provided that R ４ is not the group corresponding to the side chain of Val).

[0033] R ４ is preferably an unsubstituted C4-5 branched alkyl group or a C1-2 alkyl group substituted with a C3-C5 cycloalkyl group. Examples of unsubstituted C4-5 branched alkyl groups include an isobutyl group (—CH ２ CH (CH ３ ) ２ ) (the side chain of Leu), or a sec-butyl group (—CH(CH ３ ) CH ２ CH ３ ) (side chain of Ile), more preferably an isobutyl group. As the C1-2 alkyl group substituted with a C3-C5 cycloalkyl group, a C3-C5 cycloalkylmethyl group is preferred, more preferably a cyclopropylmethyl group or a cyclobutylmethyl group.

[0034] R ５ is preferably a linear or branched alkyl group optionally substituted with a phenyl group, an imidazoyl group, an amino group, a guanidino group, or a C1-3 thioalkyl group, more preferably a C1-4 linear or branched alkyl group optionally substituted with a phenyl group, an imidazoyl group, an amino group, a guanidino group, or a C1-3 thioalkyl group; or a phenyl group optionally substituted with a halogen atom, an alkyl group (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group), or an alkoxy group (e.g., a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group). ５may be, for example, a benzyl group (the side chain of Phe), a phenylethyl group, a 2-(methylthio)ethyl group (the side chain of Met), a 2-(methylsulfinyl)ethyl group (the side chain of MetO), an n-butyl group (the side chain of Nle), a 1-hydroxyethyl group (the side chain of Thr), a 3-guanidinopropyl group (the side chain of Arg), a 4-aminobutyl group (the side chain of Lys), a 1H-imidazol-4-yl-methyl group (the side chain of His), a phenyl group, an n-propyl group, or an isobutyl group (the side chain of Leu), and is preferably a benzyl group, a phenylethyl group, a 2-(methylthio)ethyl group, a 3-guanidinopropyl group, a 2-(methylsulfinyl)ethyl group, an n-butyl group, a phenyl group, an n-propyl group, or an isobutyl group.

[0035] R ６ is preferably a straight-chain, branched, or cyclic alkyl group or an alkoxy group, more preferably a C1-4 straight-chain or branched alkyl group, a C3-6 cycloalkyl group, or a C1-4 alkoxy group, and even more preferably an ethyl group, an n-propyl group, an isopropyl group, a methoxy group, an ethoxy group, an isopropyloxy group, a cyclopropyloxy group, cyclopropane, or cyclobutane.

[0036] R ６ Examples of substituents that may be substituted on the alkyl group or alkyl moiety, alkenyl group, or alkynyl group represented by the formula (I) include halogen, alkoxy group, phenyloxy group, alkenyl group, alkynyl group, amino group, alkylamino group, thioalkyl group, sulfinyl group, sulfonyl group, carboxyl group, nitrile group, and hydroxyl group. Among these, halogen, alkoxy group, and phenyloxy group are preferred. ６ Examples of the substituent with which the aryl group, heterocyclic group, or fused polycyclic hydrocarbon group represented by the formula (I) may be substituted include a halogen atom, an alkyl group (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group, a cyclopropyl group), an alkoxy group (e.g., a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group, a cyclopropyloxy group), and the like.

[0037] R ６As the alkoxy group as a substituent of the above, in addition to the above alkoxy groups (for example, methoxy group, ethoxy group), the above alkoxy groups further substituted with the above alkoxy groups can also be preferably used.

[0038] R ６ Halogen as a substituent of is, for example, fluorine, chlorine or bromine, preferably fluorine.

[0039] R ６ Examples of the fused polycyclic hydrocarbon group represented by the formula (I) include indanyl, indenyl, naphthyl, anthracenyl, pentalenyl, azulenyl, etc. Among these, indanyl is preferred.

[0040] Specific examples of compounds according to the present invention include compounds represented by the following formulas (wherein R １ , R ２ , and R ３ are each as defined in formula (I).

[0041] Furthermore, specific examples of compounds according to the present invention include compounds represented by the following formulas (wherein R ５ is as defined in formula (I) and is preferably a benzyl group, a phenylethyl group, a 2-(methylthio)ethyl group, a 2-(methylsulfinyl)ethyl group, an n-butyl group, a 1-hydroxyethyl group, a 3-guanidinopropyl group, a 4-aminobutyl group, a 1H-imidazol-4-yl-methyl group, a phenyl group, an n-propyl group, or an isobutyl group, and more preferably a benzyl group, a 2-(methylthio)ethyl group, a phenyl group, or an n-butyl group.

[0042] Compound (I) can be synthesized by any appropriate method. For example, compound (I) can be synthesized with reference to the methods described in the examples of the present application, the methods described in Patent Document 1, or Japanese Patent Application Laid-Open No. 2002-47256. The resulting crude product of compound (I) may be further purified. For example, the resulting crude product may be purified by reverse-phase column chromatography.

[0043] Salts of compound (I) include base addition salts, acid addition salts, amino acid salts, etc. Examples of base addition salts include metal salts such as lithium salt, sodium salt, potassium salt, calcium salt, and magnesium salt; organic amine salts such as ammonium salt, methylamine salt, dimethylamine salt, dicyclohexylamine salt, tris(hydroxymethyl)aminomethane salt, N,N-bis(hydroxyethyl)piperazine salt, 2-amino-2-methyl-1-propanol salt, ethanolamine salt, N-methylglucamine salt, L-glucamine salt, triethylamine salt, piperidine salt, and morpholine salt; and salts with basic amino acids such as lysine, δ-hydroxylysine, and arginine. Examples of acid addition salts include mineral acid salts such as hydrochloride, hydrobromide, sulfate, nitrate, and phosphate, and organic acid salts such as methanesulfonate, benzenesulfonate, paratoluenesulfonate, citrate, oxalate, acetate, propionate, tartrate, fumarate, maleate, malate, succinate, benzoate, mandelate, cinnamate, lactate, glycolate, glucuronate, ascorbate, nicotinate, and salicylate. Examples of amino acid salts include glycine salts. However, salts of the compounds of the present invention are not limited to these.

[0044] Compound (I) may have one or more asymmetric carbon atoms depending on the type of substituent, and may exist as stereoisomers such as optical isomers or diastereoisomers. Pure stereoisomers, any mixture of stereoisomers, racemates, etc. are all encompassed within the scope of the present invention. Furthermore, the compound represented by general formula (I) or a salt thereof may exist as a hydrate or solvate, and all of these substances are encompassed within the scope of the present invention. The type of solvent that forms the solvate is not particularly limited, and examples include solvents such as ethanol, acetone, and isopropanol. In this specification, unless clearly incompatible, a reference to "Compound (I)" includes any mixture of isomers or a specific stereoisomer of Compound (I), a salt (typically a pharmacologically acceptable salt), a hydrate, and a solvate of a salt (typically a pharmacologically acceptable salt) of Compound (I), even if not explicitly stated.

[0045] Compound (I) may have improved calpain inhibitory activity compared to conventional calpain inhibitors (e.g., the calpain inhibitors disclosed in Patent Document 1). Calpains are gene products having a sequence region significantly homologous to the catalytic domain of human calpain-1 (μ-calpain, μCANP, μ80K, calpain I, CDP I), and include calpains-1 to -16. For example, calpain-1 is a heterodimer of CAPN1 and CAPNS1, and calpain-2 is a heterodimer of CAPN2 and CAPNS1. Compound (I) may have inhibitory activity against, for example, calpain-1.

[0046] Compound (I) may also have excellent water solubility. The solubility (25°C) of Compound (I) in water, physiological saline, or a buffer solution (e.g., 10 mM phosphate buffer (pH 7.0)) is, for example, greater than 0.1 mg / mL, preferably greater than 0.65 mg / mL, more preferably 1.5 mg / mL or greater, and even more preferably 5.0 mg / mL or greater. In particular, Compound (I) having excellent solubility in water may be advantageous in terms of application to pharmaceutical compositions (e.g., eye drops). In one embodiment, Compound (I) may have improved water solubility compared to conventional calpain inhibitors (e.g., the calpain inhibitors disclosed in Patent Document 1).

[0047] <Calpain inhibitor or pharmaceutical composition> As described above, compound (I) can have improved calpain inhibitory activity. Thus, in one aspect, the present invention relates to a calpain inhibitor or pharmaceutical composition comprising compound (I) as an active ingredient.

[0048] For example, a calpain inhibitor can be used to inhibit the activity of calpain. The use of the calpain inhibitor can be, for example, in vitro, in vivo, or ex vivo.

[0049] Also, for example, the calpain inhibitor and the pharmaceutical composition can be used for treating or preventing diseases associated with calpain activity, respectively.

[0050] A disease associated with calpain activity may be a disease whose onset or exacerbation is contributed by the expression or activity of calpain. Examples of diseases associated with calpain activity include glaucoma including normal-tension glaucoma, autosomal dominant neovascular inflammatory vitreoretinopathy, retinitis pigmentosa, age-related macular degeneration, retinal diseases such as diabetes-associated retinal neuropathy or retinal vascular occlusive disease, and retinal ischemia, or ocular diseases such as retinal neuropathy or cataract; muscle diseases such as muscular dystrophy; diabetes; inflammatory diseases or autoimmune diseases such as acute esophagitis, multiple sclerosis, idiopathic inflammatory myopathy, and autoimmune encephalitis; and neurological diseases such as spinal cord injury, Parkinson's disease, neurodegenerative diseases, lissencephaly, Alzheimer's disease, and spinocerebellar degeneration. cardiovascular diseases such as cardiac ischemia-reperfusion injury, chronic heart disease, abdominal aortic aneurysm, and atherosclerosis; cancers such as melanoma, breast cancer, colon cancer, kidney cancer, gastric cancer, cervical cancer, and soft tissue sarcoma; brain tumors; aging syndromes; progeria; COVID-19 infection caused by SARS-coronavirus 2 or a mutant strain thereof; infections caused by parasites or pathogenic microorganisms such as malaria, trypanosomiasis, African sleeping sickness, schistosomiasis, leishmaniasis, and sickle cell disease; traumatic brain injury; Machado-Joseph disease; pre-eclampsia; and pulmonary fibrosis.

[0051] The subjects to which the calpain inhibitor or pharmaceutical composition is administered are typically humans or non-human mammals (e.g., cows, horses, dogs, cats, monkeys, pigs, sheep, rabbits, rats, mice, etc.).

[0052] The calpain inhibitor or pharmaceutical composition may be administered systemically or locally. Systemic administration can be performed by oral administration, intravenous injection, subcutaneous injection, intramuscular injection, etc. Local administration includes administration to the skin, mucosa, nose, eyes, etc.

[0053] The dosage form of the calpain inhibitor or pharmaceutical composition may be oral or parenteral, depending on the administration mode. Oral preparations include, for example, liquid preparations for oral administration such as solutions, suspensions, emulsions, and syrups, and solid preparations for oral administration such as tablets, pills, capsules, powders, granules, and lozenges. Parenteral preparations include injections such as subcutaneous injections, intravenous injections, intramuscular injections, intraperitoneal injections, and vitreous injections, eye drops, nasal drops, and topical preparations (e.g., ointments such as eye ointments).

[0054] The calpain inhibitor or pharmaceutical composition may further contain, in addition to compound (I), pharmaceutically acceptable additives depending on the dosage form, etc. The calpain inhibitor or pharmaceutical composition may be produced by known methods, for example, the methods described in the Japanese Pharmacopoeia.

[0055] For example, an oral liquid formulation can be prepared by dissolving, suspending, or emulsifying Compound (I) in a diluent (e.g., purified water, ethanol, or a mixture thereof). The liquid formulation may further contain a wetting agent, a suspending agent, an emulsifying agent, a sweetener, a flavoring agent, a fragrance, a preservative, a buffer, etc.

[0056] For example, solid preparations for oral administration are prepared by mixing Compound (I) with excipients (e.g., lactose, mannitol, glucose, microcrystalline cellulose, starch), binders (e.g., hydroxypropyl cellulose, polyvinylpyrrolidone, magnesium aluminometasilicate), disintegrants (e.g., calcium cellulose glycolate), lubricants (e.g., magnesium stearate), stabilizers, solubilizers (e.g., glutamic acid, aspartic acid), etc., according to conventional methods. If necessary, the solid preparations may be coated with a coating agent (e.g., sucrose, gelatin, hydroxypropyl cellulose, hydroxypropylmethylcellulose phthalate), or may be coated with two or more layers.

[0057] Injections, eye drops, or nasal drops may contain, for example, an isotonic agent (e.g., sodium chloride, potassium chloride, glycerin, mannitol, sorbitol, boric acid, borax, glucose, propylene glycol), a buffer (e.g., phosphate buffer, acetate buffer, borate buffer, carbonate buffer, citrate buffer, Tris buffer, glutamate buffer, epsilon aminocaproic acid buffer), a preservative (e.g., methyl parahydroxybenzoate, ethyl parahydroxybenzoate, propyl parahydroxybenzoate, chlorobutanol, benzyl alcohol, benzalkonium chloride, The composition can be produced by dissolving or dispersing compound (I) in a solution to which additives such as hydroxypropyl cellulose, sodium hydroxypropyl cellulose, sodium dehydroacetate, sodium edetate, boric acid, borax, thickeners (e.g., hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, polyethylene glycol), stabilizers (e.g., sodium hydrogen sulfite, sodium thiosulfate, sodium edetate, sodium citrate, ascorbic acid, dibutylhydroxytoluene), pH adjusters (e.g., hydrochloric acid, sodium hydroxide, phosphoric acid, acetic acid) and the like have been appropriately added.

[0058] The amount of additives added to injections, eye drops, or nasal drops can be set appropriately depending on the type of additive, intended use, etc. The isotonicity agent is typically added in an amount of about 0.5 w / v% to about 5.0 w / v% so that the osmotic pressure is about 229 mOsm to about 343 mOsm. The amount of buffer added is preferably about 0.01 w / v% to about 2.0 w / v%. The amount of thickener added is preferably about 0.01 w / v% to about 1.0 w / v%. The amount of stabilizer added is preferably about 0.001 w / v% to about 1.0 w / v%. The pH adjuster is typically added so that the pH is about 3 to about 9, preferably about 4 to about 8.

[0059] The dosage of the calpain inhibitor or pharmaceutical composition can be set at any appropriate amount depending on the target disease, symptoms, administration subject, administration method, etc. For example, when administered to adults as an oral preparation, the single dose is about 1 mg to about 200 mg (amount (i.e., potency) of compound (I)), preferably about 10 mg to about 100 mg (potency), several times a day. When administered to adults as an injection, the single dose is about 0.1 mg to about 50 mg (potency), preferably about 1 mg to about 30 mg (potency), once a day. When used topically in the eyes, it is preferable to instill about 20 μL to about 50 μL of an eye drop solution containing, for example, about 0.001 w / v % to about 1.0 w / v %, preferably about 0.01 w / v % to about 0.5 w / v %, of compound (I) several times a day.

[0060] <Preventive or therapeutic method> In one aspect, the present invention relates to a method for treating or preventing a disease associated with calpain activity, which comprises administering an effective amount of compound (I) to an individual in need of such treatment or prevention.

[0061] Compound (I) can be administered directly or in the form of a calpain inhibitor or pharmaceutical composition to an individual in need of treatment or prevention of a disease associated with calpain activity.

[0062] The diseases associated with calpain activity and the method of administering Compound (I) are as described above for the calpain inhibitor or pharmaceutical composition. Furthermore, individuals in need of treatment or prevention of diseases associated with calpain activity are individuals suffering from the disease or individuals likely to suffer from the disease (e.g., individuals exhibiting calpain activity equal to or greater than a reference value). The individuals are typically humans or mammals other than humans, similar to the subjects of administration of the calpain inhibitor or pharmaceutical composition.

[0063] The effective amount of compound (I) may be, for example, an amount that, when compound (I) is administered, provides a therapeutic or preventive effect for the above-mentioned diseases compared to when compound (I) is not administered. The specific effective amount is not generally set, but can be appropriately adjusted depending on the dosage form, administration method, purpose of use, and the age, body weight, symptoms, etc. of the individual.

[0064] The present invention will be described in more detail below using examples, but these are not intended to limit the scope of the present invention. Note that all references cited throughout this specification are incorporated herein by reference in their entirety.

[0065] Synthesis Example 1 Compound 13 was synthesized according to the scheme shown below.

[0066] (Synthesis of Compound 2)

[0067] Compound 1 (10.0 g, 46.4 mmol) and DIPEA (18.9 mL, 111 mmol) ２ Cl ２ Ethyl chloroformate (5.3 mL, 55.6 mmol) was slowly added to the solution (92.0 mL) at 0°C, and the mixture was gradually warmed to room temperature and stirred for 18 hours. Distilled water and 2 M hydrochloric acid were added, and after confirming the pH to 4, the mixture was extracted with dichloromethane. The organic phase was washed with saturated aqueous sodium bicarbonate and then saturated brine. The organic phase was dried over sodium sulfate, and the solvent was removed under reduced pressure. The resulting residue was purified using a silica gel column to obtain target compound 2 (11.5 g, 99%). １ H NMR (400MHz, CDCl ３ ) δ7.28 (2H, dd, J=7.2, 2.0Hz), 7.24 (1H, dd, J=7.2, 2.0Hz), 7.10 (2H, dd, J=7.2, 2.0Hz), 5. 07 (1H, d), 4.63 (1H, q), 4.09 (2H, q), 4.09 (2H, q), 3.70 (3H, s), 3.09 (2H, dd), 1.21 (3H, t)

[0068] (Synthesis of Compound 4)

[0069] Under a nitrogen atmosphere, diisopropylamine (24.5 mL, 172 mmol) was added to n-BuMgCl (72.0 mL, 143 mmol, 2.0 M THF solution) at 40°C over 30 minutes, and the mixture was stirred at the same temperature for 2 hours to obtain a slurry. Under a nitrogen atmosphere, the above slurry was added to a toluene solution (20.8 mL) of compound 2 (9.0 g, 35.8 mmol), dibromomethane (5.1 mL, 71.6 mmol), and 1,2-dimethoxyethane (10.4 mL, 100 mmol) at -10°C over 1.5 hours, and the mixture was stirred for 2 hours. Distilled water and 2 M hydrochloric acid were added, and the pH was confirmed to be 2. After that, the mixture was extracted with toluene, and the organic phase was washed with distilled water and then saturated saline. The organic phase was dried over sodium sulfate and then filtered. The obtained toluene solution was used in the next reaction. Potassium carbonate (12.4 g, 89.5 mmol) and N-bromosuccinimide (15.9 g, 89.5 mmol) were added to the toluene solution at 0°C, and the mixture was stirred at the same temperature for 2 hours. Distilled water was added, and the mixture was extracted with toluene. The organic phase was washed with 0.2 M hydrochloric acid and then with saturated saline. After drying the organic phase over sodium sulfate, the solvent was evaporated under reduced pressure to obtain target product 4 (15.8 g, 94%, 2 steps). １ H NMR (400MHz, CDCl ３ ) δ7.36-7.15 (5H, m), 5.65 (1H, q), 5.13 (1H, d), 4.02 (2H, q), 3.40 (1H, dd), 3.03 (1H, dd), 1.15 (3H, t)

[0070] (Synthesis of Compound 7)

[0071] Sodium borohydride (1.27 g, 33.5 mmol) was slowly added to a MeOH solution (170 mL) of compound 4 (15.8 g, 33.5 mmol) at 0°C, and the mixture was stirred for 2 hours. Distilled water and 2 M hydrochloric acid were added, and after confirming the pH to 4, the mixture was extracted with dichloromethane, and the organic phase was washed with distilled water and then with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was used in the next reaction. A 4 M aqueous solution of lithium hydroxide (83.8 mL, 335 mmol) was added to a toluene solution (80.0 mL) of the residue, and the mixture was stirred at 70°C for 16 hours. After cooling to room temperature, the organic layer and the aqueous layer were separated, and the aqueous layer was used in the next reaction. The aqueous layer was diluted with THF (100 mL) and Boc ２ 0 (14.6 g, 67.0 mmol) was added and stirred at room temperature for 18 hours. 2 M hydrochloric acid was added, and after confirming the pH to 4, the mixture was extracted with ethyl acetate and the organic phase was washed with saturated brine. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure to obtain target compound 7 (3.90 g, 39%, 3 steps). １ H NMR (400MHz, DMSO-d6) δ7.34-7.15 (6H, m), 6.39 (1H, d), 4.00 (1H, m), 3.87 (11H, m), 2.75 (2H, m), 1.31 (9H, m)

[0072] (Synthesis of Compound 8)

[0073] To a DMF solution (60.0 mL) of compound 7 (3.60 g, 12.2 mmol), DIPEA (4.30 mL, 24.4 mmol), and cyclopropylamine (1.02 mL, 14.6 mmol), HATU (5.10 g, 13.4 mmol) was added and stirred for 4 hours. 0.2 M hydrochloric acid was added, and after confirming the pH to 4, the mixture was extracted with MTBE and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain the target compound 8 (1.17 g, 29%). １H NMR (400MHz, DMSO-d6) δ7.75 (1H, m), 7.32-7.14 (5H, m), 6.50 (0.5H, d), 6.14 (0.5H, d), 5.67 (0.5H, d), 5.50 (0.5H, d), 3.97 (1.5H, m) , 3.77 (0.5H, dd), 2.78 (0.5H, m), 2.68-2.53 (2.5H, m), 1.28 (4.5H, s), 1.21 (4.5H, s), 0.58 (2H, m), 0.47 (2H, m)

[0074] (Synthesis of Compound 9)

[0075] Compound 8 (429 mg, 1.28 mmol) was added with 4 M hydrochloric acid (6.40 mL, 25.6 mmol, dioxane solution) and stirred at room temperature for 1 hour. The solvent was evaporated under reduced pressure to give target compound 9 (339 mg, 97%). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,235.1441;found,235.1434(-0.7mmu)

[0076] (Synthesis of Compound 10)

[0077] To a DMF solution (1.0 mL) of compound 9 (50.0 mg, 0.185 mmol), DIPEA (0.095 mL, 0.56 mmol), and Fmoc-Leu-OH (71.8 mg, 0.203 mmol), HATU (77.2 mg, 0.203 mmol) was added and stirred for 2 hours. 0.2 M hydrochloric acid was added, and after confirming that the pH was 4, extraction was performed with MTBE, and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain target compound 10 (49.6 mg, 46%). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,570.2962;found,570.2955(-0.7mmu)

[0078] (Synthesis of Compound 11)

[0079] Compound 10 (49.6 mg, 0.087 mmol) and CH ２ Cl ２Diethylamine (1.0 mL) was added to the solution (4.0 mL) and stirred at room temperature for 2 hours. The solvent was evaporated under reduced pressure, hexane was added to the resulting residue, and the resulting solid was filtered to obtain the target compound 11 (30.3 mg, quant.). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,348.2282;found,348.2273(-0.9mmu)

[0080] (Synthesis of Compound 12)

[0081] HATU (33.1 mg, 0.087 mmol) was added to a DMF solution (1.0 mL) of compound 11 (30.3 mg, 0.087 mmol), DIPEA (0.043 mL, 0.26 mmol), and methoxyacetic acid (0.0073 mL, 0.096 mmol), and the mixture was stirred for 2 hours. 0.2 M hydrochloric acid was added, and the pH was confirmed to be 4. The mixture was then extracted with MTBE, and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain target compound 12 (13.4 mg, 37%). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,420.2493;found,420.2483(-1.0mmu)

[0082] (Synthesis of Compound 13)

[0083] Compound 12 (13.4 mg, 0.032 mmol) and sodium bicarbonate (43 mg, 0.26 mmol) ２ Cl ２ DMPI (27.1 mg, 0.064 mmol) was added to the solution (3.0 mL) and stirred for 5 hours. A saturated aqueous solution of sodium bicarbonate and a saturated aqueous solution of sodium thiosulfate were added, and the mixture was diluted with CH ２ Cl ２ The organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain the target compound 13 (6.3 mg, 47%). HRMS (ESI ＋ ): calcd for [M+H] ＋,418.2336;found,418.2331(-0.5mmu) １ H NMR (400MHz, DMSO-d6) δ8.72 (1H, d), 8.40 (1H, d), 7.53 (1H, d), 7.30-7.08 (5H, m), 5.13 (1H, m), 4.37 (1H, m), 3.75 (2H, d), 3.23 (3H, s), 3.0 8 (1H, dd), 2.75 (1H, dd), 2.69 (1H, m), 1.45 (1H, m), 1.36 (2H, m), 0.82 (3H, d), 0.79 (3H, d), 0.61 (2H, m), 0.53 (2H, m)

[0084] Synthesis Example 2 Compound 14 was synthesized according to the scheme shown below.

[0085] To a DMF solution (1.2 mL) of compound 11 (20.0 mg, 0.058 mmol), DIPEA (0.029 mL, 0.17 mmol), and 2-methoxy-2-methylpropanoic acid (0.0071 mL, 0.063 mmol), HATU (21.9 mg, 0.058 mmol) was added and stirred for 2 hours. 0.2 M hydrochloric acid was added, and after confirming that the pH was 4, the mixture was extracted with MTBE and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure to obtain compound 14p. This was used in the next reaction. CH ２ Cl ２ DMPI (49 mg, 0.12 mmol) was added to the solution (1.0 mL) and stirred for 2 hours. A saturated aqueous solution of sodium bicarbonate and a saturated aqueous solution of sodium thiosulfate were added, and the mixture was diluted with CH ２ Cl ２ The organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain the target compound 14 (11.8 mg, 46%, 2 steps). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,446.2649;found,446.2650(-0.1mmu) １H NMR (400 MHz, DMSO-d6): 1H NMR (400 MHz, DMSO-d6): δ8.73 (1H, d), 8.28 (1H, d), 7.46 (1H, d), 7.27-7.09 (5H, m), 5.15 (1H, m), 4.30 (1H, m), 3.06 (3H, s), 3.10 (1H, dd), 2.72 (1H, dd), 2 .62 (1H, m), 1.42 (1H, m), 1.32 (2H, m), 1.19 (3H, s), 1.16 (3H, s), 0.81 (3H, d), 0.78 (3H, d), 0.61 (2H, m), 0.54 (2H, m)

[0086] Synthesis Example 3 Compound 15 was synthesized according to the scheme shown below.

[0087] To a DMF solution (1.2 mL) of compound 11 (20.0 mg, 0.058 mmol), DIPEA (0.029 mL, 0.17 mmol), and 2-[2-(2-Methoxyethoxy)ethoxy]acetic acid (0.0097 mL, 0.063 mmol), HATU (21.9 mg, 0.058 mmol) was added and stirred for 2 hours. 0.2 M hydrochloric acid was added, and after confirming that the pH was 4, the mixture was extracted with MTBE and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure to obtain compound 15p. This was used in the next reaction. CH ２ Cl ２ DMPI (49 mg, 0.12 mmol) was added to the solution (1.0 mL) and stirred for 2 hours. A saturated aqueous solution of sodium bicarbonate and a saturated aqueous solution of sodium thiosulfate were added, and the mixture was diluted with CH ２ Cl ２ The organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain the target compound 15 (8.7 mg, 30%, 2 steps). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,506・2861;found,506.2856(-0.5mmu) １H NMR (400MHz, DMSO-d6): δ8.71 (1H, d), 8.42 (1H, d), 7.45 (1H, d), 7.30-7.07 (5H, m), 5.13 (1H, m), 4.37 (1H, m), 3.83 (2H, br-s), 3.56-3.45 (6H, m), 3.39 (2H, m) , 3.19 (3H, s), 3.08 (1H, dd), 2.74 (1H, dd), 2.70 (1H, m), 1.47 (1H, m), 1.37 (2H, m), 0.83 (3H, d), 0.80 (3H, d), 0.62 (2H, m), 0.54 (2H, m)

[0088] Synthesis Example 4 Compound 16 was synthesized according to the scheme shown below.

[0089] To a DMF solution (1.0 mL) of compound 11 (50.0 mg, 0.14 mmol), DIPEA (0.075 mL, 0.43 mmol), and 2-(methylthio)acetic acid (0.014 mL, 0.16 mmol), HATU (54.7 mg, 0.14 mmol) was added and stirred for 2 hours. 0.2 M hydrochloric acid was added, and after confirming the pH to 4, the mixture was extracted with MTBE and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure to obtain compound 16p. Compound 16p (15.6 mg, 0.036 mmol) and pyridine (0.014 mL, 0.18 mmol) were dissolved in CH ２ Cl ２ DMPI (15 mg, 0.036 mmol) was added to the solution (1.0 mL) and stirred for 1 hour. A saturated aqueous solution of sodium bicarbonate and a saturated aqueous solution of sodium thiosulfate were added, and the mixture was diluted with CH ２ Cl ２ The organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain the target compound 16 (6.9 mg, 44%). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,434.2108;found,434.2094(-1.4mmu) １H NMR (400MHz, DMSO-d6): δ8.70 (1H, d), 8.37 (1H, d), 7.97 (1H, d), 7.29-7.08 (5H, m), 5.15 (1H, m), 4.33 (1H, m), 3.07 (1H, dd), 3.02 (2H, d), 2. 76 (1H, dd), 2.68 (1H, m), 1.99 (3H, s), 1.52 (1H, m), 1.34 (2H, m), 0.83 (3H, d), 0.80 (3H, d), 0.61 (2H, m), 0.53 (2H, m)

[0090] Synthesis Example 5 Compound 17 was synthesized according to the scheme shown below.

[0091] To a DMF solution (0.5 mL) of compound 11 (20.0 mg, 0.058 mmol), DIPEA (0.029 mL, 0.17 mmol), and (2R)-Tetrahydro-2-furancarboxylic acid (0.006 mL, 0.063 mmol), HATU (22.0 mg, 0.058 mmol) was added and stirred for 2 hours. 0.2 M hydrochloric acid was added, and after confirming that the pH was 4, the mixture was extracted with MTBE and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure to obtain compound 17p. This was used in the next reaction. CH ２ Cl ２ DMPI (49 mg, 0.12 mmol) was added to the solution (0.5 mL) and stirred for 2 hours. A saturated aqueous solution of sodium bicarbonate and a saturated aqueous solution of sodium thiosulfate were added, and the mixture was diluted with CH ２ Cl ２ The organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain the target compound 17 (5.4 mg, 21%, 2 steps). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,444.2493;found,444.2473(-2.0mmu) １H NMR (400MHz, DMSO-d6): δ8.78 (1H, d), 8.38 (1H, d), 7.48 (1H, d), 7.27-7.07 (5H, m), 5.13 (1H, m), 4.30 (1H, m), 3.80 (1H, m), 3.69 (1H, m), 3.10 (1H, m), 2. 73 (1H, dd), 2.66 (1H, m), 2.01 (1H, m), 1.71 (4H, m), 1.40 (1H, m), 1.30 (2H, m), 0.82 (3H, d), 0.78 (3H, d), 0.62 (2H, m), 0.54 (2H, m)

[0092] Synthesis Example 6 Compound 18 was synthesized according to the scheme shown below.

[0093] To a DMF solution (0.5 mL) of compound 11 (20.0 mg, 0.058 mmol), DIPEA (0.029 mL, 0.17 mmol), and 2-(2-Propyn-1-yloxy)acetic acid (0.0072 mL, 0.063 mmol), HATU (22.0 mg, 0.058 mmol) was added and stirred for 2 hours. 0.2 M hydrochloric acid was added, and after confirming the pH to 4, the mixture was extracted with MTBE and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure to obtain compound 18p (7.2 mg, 28%). Compound 18p (7.2 mg, 0.016 mmol) and sodium bicarbonate (54 mg, 0.065 mmol) were subjected to CH ２ Cl ２ DMPI (13.7 mg, 0.032 mmol) was added to the solution (1.0 mL) and stirred for 2 hours. A saturated aqueous solution of sodium bicarbonate and a saturated aqueous solution of sodium thiosulfate were added, and the mixture was diluted with CH ２ Cl ２ The organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain the target compound 18 (5.1 mg, 71%). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,442.2336;found,442.2313(-2.3mmu) １H NMR (400MHz, DMSO-d6): δ8.70 (1H, d), 8.40 (1H, d), 7.59 (1H, d), 7.39-7.10 (5H, m), 5.12 (1H, m), 4.36 (1H, m), 4.16 (2H, d), 3.87 (2H, s), 3.50 (1H, m), 3.08 (1H, dd), 2.75 (1H, dd), 2.68 (1H, m), 1.46 (1H, m), 1.36 (2H, m), 0.82 (3H, d), 0.79 (3H, d), 0.61 (2H, m), 0.53 (2H, m)

[0094] Synthesis Example 7 Compound 19 was synthesized as a comparative compound according to the scheme shown below.

[0095] To a DMF solution (0.5 mL) of compound 11 (20.0 mg, 0.058 mmol), DIPEA (0.029 mL, 0.17 mmol), and 3-methoxypropanoic acid (6.6 mg, 0.063 mmol), HATU (22.0 mg, 0.058 mmol) was added and stirred for 2 hours. 0.2 M hydrochloric acid was added, and after confirming the pH to 4, the mixture was extracted with MTBE and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure to obtain compound 19p (7.7 mg, 31%). Compound 19p (7.7 mg, 0.018 mmol) and sodium bicarbonate (6.0 mg, 0.071 mmol) were subjected to CH ２ Cl ２ To the solution (1.0 mL), DMPI (15 mg, 0.035 mmol) was added and stirred for 2 hours. A saturated aqueous solution of sodium bicarbonate and a saturated aqueous solution of sodium thiosulfate were added, and the mixture was subjected to CH ２ Cl ２ The organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain the target compound 19 (3.4 mg, 44%). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,432.2493;found,432.2471(-2.2mmu) １H NMR (400MHz, DMSO-d6): δ8.69 (1H, d), 8.25 (1H, d), 7.87 (1H, d), 7.28-7.09 (5H, m), 5.12 (1H, m), 4.30 (1H, m), 3.43 (2H, m), 3.14 (3H, s), 3.07 (1H, dd), 2.76 (1H, dd), 2.67 (1H, m), 2.27 (2H, m), 1.51 (1H, m), 1.30 (2H, m), 0.82 (3H, d), 0.77 (3H, d), 0.61 (2H, m), 0.53 (2H, m)

[0096] Synthesis Example 8 Compound 27 was synthesized according to the scheme shown below. To a DMF solution (1.0 mL) of compound 11 (25.0 mg, 0.072 mmol), DIPEA (0.037 mL, 0.22 mmol), and 2-furoic acid (8.8 mg, 0.063 mmol), HATU (30.0 mg, 0.079 mmol) was added and stirred for 2 hours. 0.2 M hydrochloric acid was added, and after confirming that the pH was 4, the mixture was extracted with MTBE and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure to obtain compound 27p. A CH ２ Cl ２ DMPI (45.0 mg, 0.11 mmol) was added to the solution (1.0 mL) and stirred for 2 hours. A saturated aqueous solution of sodium bicarbonate and a saturated aqueous solution of sodium thiosulfate were added, and the mixture was diluted with CH ２ Cl ２ The organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain the target compound 27 (13.0 mg, 41%, 2 steps). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,440.2180;found,440.2156(-2.4mmu) １ H NMR (400MHz, CDCl ３): δ7.45 (1H, m), 7.14-7.09 (4H, m), 7.07-7.01 (2H, m), 6.90 (1H, d), 6.69 (1H, d), 6.53 (1H, d), 6.52 (1H, d), 5.54 (1H, m), 4.57 (1 H, m), 3.33 (1H, dd), 3.02 (1H, dd), 2.79 (1H, m), 1.65 (1H, m), 1.55 (2H, m), 0.91 (3H, d), 0.89 (3H, d), 0.86 (2H, m), 0.60 (2H, m)

[0097] Synthesis Example 9 Compound 30 was synthesized according to the scheme shown below.

[0098] (Synthesis of Compound 30n) Fmoc-β-cyclopropyl-L-Alanine (200 mg, 0.57 mmol), DIPEA (0.30 mL, 1.72 mmol), 2-Chlorotrityl Chloride Resin (244 mg, 0.38 mmol), and CH ２ Cl ２ (4.0 mL) was added to a plastic container and shaken thoroughly for 17 hours. The reaction solution was filtered, and the filtered product was added to CH ２ Cl ２ The filtered product was transferred to a plastic container, and a piperidine:DMF=1:4 solution (5.0 mL) was added, followed by vigorous shaking for 1 hour. The reaction solution was filtered, and the filtered product was washed with DMF (5.0 mL), then with CH ２ Cl ２ The filtered material was transferred to a plastic container, and DIPEA (0.27 mL, 1.55 mmol), methoxyacetic acid (0.058 mL, 0.76 mmol), a DMF solution (5.0 mL), and HATU (0.29 g, 0.76 mmol) were added, followed by vigorous shaking for 3 hours. The reaction solution was filtered, and the filtered material was washed with DMF (5.0 mL), followed by CH ２ Cl ２The residue was transferred to a plastic filter, TFA (4.0 mL) was added, and the mixture was left to stand for 2 hours. The reaction solution was filtered, and the residue was washed with TFA (4.0 mL). The filtrate was concentrated under reduced pressure to give the target compound 30n (76 mg, 99%, 4 steps).

[0099] (Synthesis of Compound 30) To a DMF solution (1.5 mL) of compound 9 (40 mg, 0.15 mmol), DIPEA (0.075 mL, 0.44 mmol), and compound 30n (30 mg, 0.15 mmol), HATU (56 mg, 0.15 mmol) was added and stirred for 2 hours. 0.2 M hydrochloric acid was added, and after confirming the pH to 4, the mixture was extracted with MTBE and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure to obtain compound 30p (18 mg, 29%). Compound 30p (18 mg, 0.043 mmol) and sodium bicarbonate (11 mg, 0.13 mmol) were subjected to CH ２ Cl ２ DMPI (28 mg, 0.066 mmol) was added to the solution (1.0 mL) and stirred for 2 hours. A saturated aqueous solution of sodium bicarbonate and a saturated aqueous solution of sodium thiosulfate were added, and the mixture was diluted with CH ２ Cl ２ The organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain the target compound 30 (4.8 mg, 27%). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,416.2180;found,416.2153(-2.7mmu) １ H NMR (400MHz, DMSO-d6): δ8.71 (1H, d), 8.39 (1H, d), 7.52 (1H, d), 7.30-7.09 (5H, m), 5.16 (1H, m), 4.38 (1H, m), 3.76 (2H, d), 3.25 ( 3H, s), 3.08 (1H, dd), 2.75 (1H, dd), 2.65 (1H, m), 1.43 (2H, m), 0.66-0.47 (5H, m), 0.30 (2H, m), 0.00 (2H, m)

[0100] Synthesis Example 10 Compound 35 was synthesized according to the scheme shown below.

[0101] (Synthesis of Compound 35n) β-Cyclobutyl-L-alanine (0.10 g, 0.70 mmol) was dissolved in 2 M aqueous sodium hydroxide (0.70 mL), and then methoxyacetic acid (0.083 mL, 0.90 mmol) was added and stirred at room temperature for 5 hours. 2 M hydrochloric acid was added, and after confirming the pH to 4, the mixture was extracted with ethyl acetate, and the organic phase was washed with saturated brine. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. MTBE (1.0 mL) and hexane (5.0 mL) were added to the resulting residue, and the resulting solid was filtered to obtain compound 35n (12 mg, 8%).

[0102] (Synthesis of Compound 35) To a DMF solution (1.0 mL) of compound 9 (20 mg, 0.073 mmol), DIPEA (0.029 mL, 0.17 mmol), and 35n (12 mg, 0.056 mmol), HATU (21 mg, 0.056 mmol) was added and stirred for 2 hours. 0.2 M hydrochloric acid was added, and after confirming the pH to 4, the mixture was extracted with MTBE and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure to obtain compound 35p (12 mg, 49%). Compound 35p (12 mg, 0.028 mmol) and sodium bicarbonate (7.1 mg, 0.086 mmol) were subjected to CH ２ Cl ２ DMPI (18 mg, 0.043 mmol) was added to the solution (1.0 mL) and stirred for 2 hours. A saturated aqueous solution of sodium bicarbonate and a saturated aqueous solution of sodium thiosulfate were added, and the mixture was subjected to CH ２ Cl ２ The organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain the target compound 35 (3.0 mg, 25%). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,430.2336;found,430.2336(0.0mmu) １H NMR (400MHz, DMSO-d6): δ8.72 (1H, d), 8.38 (1H, d), 7.42 (1H, d), 7.28-7.12 (5H, m), 5.13 (1H, m), 4.24 (1H, m), 3.74 (2H, d), 3.24 (3H, s), 3.08 (1 H, dd), 2.74 (1H, dd), 2.70 (1H, m), 2.15 (1H, m), 1.90 (1H, m), 1.90 (1H, m), 1.75-1.48 (6H, m), 0.62 (2H, m)), 0.54 (2H, m)

[0103] Synthesis Example 11 Compound 36 was synthesized according to the scheme shown below.

[0104] (Synthesis of Compound 36n) Fmoc-Leu-OH (2.5 g, 7.1 mmol), DIPEA (3.8 mL, 22 mmol), 2-Chlorotrityl Chloride Resin (3.1 g, 4.8 mmol), and CH ２ Cl ２ (16 mL) was added to a plastic container and shaken thoroughly for 20 hours. The reaction solution was filtered, and the filtered product was added to CH ２ Cl ２ A portion of the filtered product (0.19 g, 0.20 mmol) was transferred to a plastic bag, and a piperidine:DMF=1:4 solution (0.4 mL) was added, followed by vigorous shaking for 1 hour. The reaction solution was filtered, and the filtered product was washed with DMF (1.0 mL), then with CH ２ Cl ２ The filtered product was transferred to a plastic container, and DIPEA (0.14 mL, 0.82 mmol), 2-furoic acid (45 mg, 0.40 mmol), a DMF solution (2.0 mL), and HATU (0.15 g, 0.40 mmol) were added, followed by vigorous shaking and mixing for 3 hours. The reaction solution was filtered, and the filtered product was washed with DMF (3.0 mL), followed by CH ２ Cl ２The filtered product was transferred to a plastic filter, TFA (2.0 mL) was added, and the mixture was left to stand for 2 hours. The reaction solution was filtered, and the filtered product was washed with TFA (2.0 mL). The filtrate was concentrated under reduced pressure to give the target compound 36n (45 mg, quant., 3 steps).

[0105] (Synthesis of Compound 36) To a DMF solution (1.0 mL) of commercially available (ChemScene) compound 36o (20 mg, 0.084 mmol), DIPEA (0.043 mL, 0.25 mmol), and compound 36n (19 mg, 0.084 mmol), HATU (32 mg, 0.084 mmol) was added and stirred for 2 hours. 0.2 M hydrochloric acid was added, and after confirming the pH to 4, the mixture was extracted with MTBE and the organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure to obtain compound 36p (34 mg, 99%). Compound 36p (34 mg, 0.083 mmol) and sodium bicarbonate (21 mg, 0.25 mmol) were subjected to CH ２ Cl ２ DMPI (53 mg, 0.13 mmol) was added to the solution (1.0 mL) and stirred for 2 hours. A saturated aqueous solution of sodium bicarbonate and a saturated aqueous solution of sodium thiosulfate were added, and the mixture was diluted with CH ２ Cl ２ The organic phase was washed with saturated saline. The organic phase was dried over sodium sulfate, and the solvent was evaporated under reduced pressure. The resulting residue was purified using a silica gel column to obtain the target compound 36 (31 mg, 92%). HRMS (ESI ＋ ): calcd for [M+H] ＋ ,406.2336;found,406.2304(-3.2mmu) １ H NMR (400MHz, DMSO-d6): δ8.68 (1H, d), 8.29 (1H, d), 8.15 (1H, d), 7.80 (1H, s), 7.15 (1H, d), 6.58 (1H, dd), 4.90 (1H, m), 4.50 (1H, m), 2.6 9 (1H, m), 1.70 (1H, m), 1.57 (2H, m), 1.45 (2H, m), 1.37-1.14 (4H, m), 0.92-0.75 (9H, m), 0.60 (2H, m), 0.52 (2H, m)

[0106] Compounds 13 to 18, 27, 30, 35, and 36 synthesized in Synthesis Examples 1 to 11 above, compounds 20, 22, 25, 26, 28, 29, 31 to 34, and 37 to 43 synthesized according to these Synthesis Examples, and compounds 21, 23, 24, and 44 that can be synthesized are shown in Tables 1A to 1D.

[0107]

[0108]

[0109]

[0110]

[0111] <<Measurement of calpain inhibitory activity 1>> Calpain inhibitory activity was measured using SensorLyte （Ｒ） The activity was measured using the 520 Calpain Activity Assay Kit (AnaSpec, AS-72149) according to the method described in the assay protocol. SNJ1945 (Medkoo Biosciences, Inc. Cat#564979), Compound 13, Compound 14, Compound 18, or Compound 19 as a calpain inhibitor was mixed with calpain (calpain-1) included in the kit in Assay Buffer and incubated at 37°C for 3 minutes. 5-FAM / QXL, a calpain enzyme substrate, was used. ＴＭ 520 was added, and the enzyme reaction by calpain was carried out at 37°C for 25 minutes (the final concentration of each inhibitor was 0.062 μM, 5-FAM / QXL ＴＭ The final concentration of 520 was 5.0 μM. In this enzyme reaction, the enzyme substrate was cleaved by calpain, emitting fluorescence. The emitted fluorescence intensity was measured using a plate reader (Infinite （Ｒ） Detection was performed using a spectrophotometer (TECAN) (excitation wavelength: 490 nm, fluorescence wavelength: 520 nm). The increase in fluorescence is shown in Figure 1. SNJ1945 is a known calpain inhibitor and has the structure shown below.

[0112] 1 shows that the enzymatic activity of calpain is inhibited by SNJ1945. Compounds 13, 14, and 18 were confirmed to have stronger enzyme inhibitory activity than SNJ1945. On the other hand, compound 19 had inhibitory activity comparable to that of SNJ1945. These results suggest that calpain inhibitory ability can be improved by attaching an amide group having an α-carbon bonded to an oxygen atom or sulfur atom to the N-terminus of the compound of formula I.

[0113] <Measurement of calpain inhibitory activity 2> Various concentrations of SNJ1945 or Compound 13 were added to 50 mM TRIS buffer (pH 7.4, 5 mM CaCl ２ A fluorescent assay was performed by adding a DMSO solution of calpain-1 (Calpain-1 from Human Erythrocytes, Cat. No. 208713, Merck Millipore) and the HMRG fluorescent probe for detecting calpain activity to a medium containing 2 mM SNJ1945, 2 mM DTE, and 2 mM EGTA (final concentration of the fluorescent probe: 5 μM, final concentration of calpain-1: 6.48 μg / mL). The enzymatic reaction was carried out at 37°C, and the fluorescence spectrum of the reaction solution was observed over a 30-minute period from the start of the reaction (excitation wavelength: 460 nm, fluorescence wavelength: 530 nm). The results are shown in Figure 2 (the concentrations shown in the figure are the final concentrations of SNJ1945 or Compound 13 in each assay). The compounds shown below were used as probes for detecting calpain activity.

[0114] Based on the graph created using the data analysis software "KaleidaGraph", IC ５０ The IC of compound 13 was ５０ is 0.010 μM, and the IC ５０ was 0.040 μM.

[0115] <Measurement of calpain inhibitory activity 3> Compounds 13, 20, 25, 26, 27, 28, 29, 30, 31, 32, 33, 36, and 37 were added to 50 mM TRIS buffer (pH 7.4, 5 mM CaCl ２A fluorescence assay was performed by adding a DMSO solution of calpain-1 (Calpain-1 from Human Erythrocytes, Cat. No. 208713, Merck Millipore) and the HMRG fluorescent probe for detecting calpain activity to a medium containing 2 mM erythrocytes, 2 mM DTE, and 2 mM EGTA (final concentration of each compound: 0.062 μM, final concentration of the fluorescent probe: 5 μM, final concentration of calpain-1: 6.48 μg / mL). The enzyme reaction was carried out at 37°C, and the fluorescence spectrum of the reaction solution was observed over a 30-minute period from the start of the reaction (excitation wavelength: 460 nm, fluorescence wavelength: 530 nm). The results are shown in Figure 3. The same compound as in Measurement 2 above was used as the calpain activity detection probe.

[0116] As shown in FIG. 3, all of the compounds exhibited calpain inhibitory activity comparable to or greater than that of compound 13.

[0117] Compound (I), a calpain inhibitor, or a pharmaceutical composition of the present invention can be suitably used in the treatment or prevention of diseases associated with calpain activity.

Claims

1. A compound represented by the following general formula (I) or a salt thereof. 【Chemistry 1】 (In formula (I), R １ R represents a hydrogen atom; a optionally substituted linear, branched, or cyclic alkyl group; an optionally substituted linear or branched alkenyl group; an optionally substituted linear or branched alkynyl group; an optionally substituted aryl group; or an optionally substituted heterocyclic group, or R ２ They may also be bonded together to form a ring, R ２ and R ３ each independently represents a hydrogen atom; a hydroxyl group; an optionally substituted alkoxy group; or an optionally substituted straight-chain, branched, or cyclic alkyl group, or ２ R ３ and R ２ may combine to form a ring, provided that when １ R combines with R ３ to form a ring containing a double bond, R ３ may not be present. R ４ This represents a hydrogen atom; a linear or branched alkyl group having 4 or more carbon atoms, which may be substituted; or an alkyl group having 1 or 2 carbon atoms substituted with a cycloalkyl group having 3 to 5 carbon atoms. R ５ This represents a hydrogen atom; an optionally substituted linear or branched alkyl group; an optionally substituted linear or branched alkenyl group; an optionally substituted linear or branched alkynyl group; an optionally substituted aryl group; or an optionally substituted heterocyclic group. R ６ This represents a linear, branched, or cyclic alkyl group which may be substituted; a linear or branched alkenyl group which may be substituted; a linear or branched alkynyl group which may be substituted; an aryl group which may be substituted; a heterocyclic group which may be substituted; a fused polycyclic hydrocarbon group which may be substituted; an alkoxy group which may be substituted; or a hydrogen atom. X represents O or S, R １ and R ２ When they bond to form a ring, R １ can represent O, S, or N, and R ２ This can represent O or S. L is an amide bond, ester bond, -NH-, -N-(linear, branched, or cyclic alkylene)-, or -(linear or branched alkylene-O-) ｎ - (where n is an integer between 1 and 10) or single associativity.

2. In the above formula (I), -X-L-R １ The compound or salt thereof according to claim 1, wherein the group represented by is the group represented by the following formula (II). 【Chemistry 2】 (In equation (II), n represents an integer between 0 and 10.)

3. In the above formula (I), -X-L-R １ The compound or salt thereof according to claim 1, wherein the group represented is a hydroxyl group, a thiol group, or a group selected from the following. 【Transformation 3】

4. In the above formula (I), 【Chemistry 4】 The substructure represented by the following formula (where m is an integer from 1 to 3, and q is 0 or 1): 【Transformation 5】 The structure represented by the following formula (R ７ (where 'p' represents a substituent that is identical or different and bonded to the heterocycle, and 'p' represents an integer between 0 and 3.) 【Transformation 6】 A compound or salt thereof according to claim 1, selected from the structures represented by the following:

5. R ２ and R ３ The compound or salt thereof according to claim 1, wherein each of them is independently a hydrogen atom or an alkyl group, or is bonded to each other to form a cycloalkyl group.

6. In the above formula (I), R ４ The compound or salt thereof according to claim 1, wherein the compound represents an isobutyl group, a sec-butyl group, a cyclopropylmethyl group, or a cyclobutylmethyl group.

7. In the above formula (I), R ５ The compound or salt thereof according to claim 1, wherein the group represents a benzyl group, a phenylethyl group, a 2-(methylthio)ethyl group, a 2-(methylsulfinyl)ethyl group, an n-butyl group, a 1-hydroxyethyl group, a 3-guanidinopropyl group, a 4-aminobutyl group, a 1H-imidazole-4-ylmethyl group, a phenyl group, an n-propyl group, or an isobutyl group.

8. A compound according to claim 1 or a salt thereof, selected from compounds represented by the following formula. 【Transformation 7】 (In the formula, R １ , R ２ , and R ３ These are defined as described above with respect to formula (I).

9. A compound according to claim 1 or a salt thereof, selected from compounds represented by the following formula. 【Transformation 8】 (In the formula, R ５ This is as defined with respect to formula (I) above.

10. R ５ The compound or salt thereof according to claim 9, wherein the group represents a benzyl group, a phenylethyl group, a 2-(methylthio)ethyl group, a 2-(methylsulfinyl)ethyl group, an n-butyl group, a 1-hydroxyethyl group, a 3-guanidinopropyl group, a 4-aminobutyl group, a 1H-imidazole-4-ylmethyl group, a phenyl group, an n-propyl group, or an isobutyl group.

11. A calpain inhibitor comprising a compound or salt thereof according to any one of claims 1 to 10.

12. A pharmaceutical composition for treating or preventing diseases related to calpain activity, comprising a compound or salt thereof as described in any one of claims 1 to 10.

13. The pharmaceutical composition according to claim 12, wherein the disease associated with the calpain activity is an eye disease, muscle disease, diabetes, inflammatory disease, autoimmune disease, neurological disease, cardiovascular disease, cancer, brain tumor, aging syndrome, progeria, infectious disease, traumatic brain injury, Macadjos Joseph disease, preeclampsia, or pulmonary fibrosis.

14. The pharmaceutical composition according to claim 13, wherein the eye disease is glaucoma, autosomal dominant neovascular inflammatory vitreoretinopathy, retinitis pigmentosa, age-related macular degeneration, retinal neuropathy or retinal vascular occlusive disease associated with diabetes, retinal ischemia, or cataract.

15. The pharmaceutical composition according to claim 14, wherein the glaucoma is normal-tension glaucoma.

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