Dipeptide compounds and their use as antiviral agents

A dipeptide compound represented by the following formula (II) or a pharmaceutically acceptable salt thereof,

• wherein R1, R2, and R3 independently represent a linear or branched, saturated or unsaturated lower alkyl group, alkoxyl group, alkyl amino group, or dialkyl amino group having 1-4 carbon atoms (wherein a carbon atom in said alkyl, alkoxyl, alkyl amino or dialkyl amino group is optionally replaced with an oxygen atom), a halogeno group, or a hydrogen atom, provided that all of the R1, R2, and R3 are not a hydrogen atom at the same time, R2 and R3 may form a ring together;
• R4 represents a linear or branched lower alkyl group having 1-4 carbon atoms or a hydrogen atom;
• X is a methylene group or a sulfur atom;
• Y represents a five or six member monocyclic or polycyclic hydrocarbon group, a heterocyclic group having a structure in which one or more carbon atoms in the monocyclic or polycyclic hydrocarbon group is replaced by a heteroatom, an aryloxyalkyl group having 12 or less carbon atoms, in which the aromatic ring may be substituted with an alkyl group, alkoxy group, halogeno group, amino group or hydroxyl group;
• and Z represents an aliphatic hydrocarbon group having 1-6 carbon atoms or an aromatic hydrocarbon group having 12 or less carbon atoms in which the aromatic ring may be substituted with an alkyl group, alkoxy group, or halogeno group, or one or more carbon atom in the aromatic hydrocarbon group may be replaced by a heteroatom.

A dipeptide compound represented by the following formula (I) or a pharmaceutically acceptable salt thereof,

• wherein R1, R2, and R3 independently represent a linear or branched, saturated or unsaturated lower alkyl group, alkoxyl group, alkyl ammo group, or dialkyl amino group having 1-4 carbon atoms (wherein a carbon atom in said alkyl, alkoxyl, alkyl amino or dialkyl amino group is optionally replaced with an oxygen atom), a halogeno group, or a hydrogen atom, provided that all of the R1, R2, and R3 are not a hydrogen atom at the same time, R2 and R3 may form a ring together;
• R4 represents a linear or branched lower alkyl group having 1-4 carbon atoms or a hydrogen atom;
• X is a methylene group or a sulfur atom;
• Y is a group represented by the following formula (III) or formula (IV);
• and Z is a group represented by the following formula (V) or formula (VI), or a linear or branched lower alkyl group having 6 or less carbon atoms;
• wherein R5 represents a linear or branched lower alkyl group having 1-4 carbon atoms or a halogeno group, R6 represents an amino group or hydroxyl group R7, R8, and R9 respectively represent a hydrogen atom, methyl group, or fluoro group R10, R11, R12, R13 and R14 individually represent a linear or branched lower alkyl or alkoxy group having 1-4 carbon atoms, halogeno group, or a hydrogen atom, R15, R16, R17, R18 and R19 individually represent a linear or branched lower alkyl or alkoxy group having 1-4 carbon atoms, a halogeno group, or a hydrogen atom, and Q represents an alkylene group, n is 1, and m is 0-6.

A dipeptide compound represented by the following formula (II) or a pharmaceutically acceptable salt thereof,

• wherein R1, R2, and R3 independently represent a linear or branched, saturated or unsaturated lower alkyl group, alkoxyl group, alkyl amino group, or dialkyl amino group having 1-4 carbon atoms (wherein a carbon atom in said alkyl, alkoxyl, alkyl amino or dialkyl amino group is optionally replaced with an oxygen atom), a halogeno group, or a hydrogen atom, provided that all of the R1, R2, and R3 are not a hydrogen atom at the same time, R2 and R3 may form a ring together;
• R4 represents a linear or branched lower alkyl group having 1-4 carbon atoms or a hydrogen atom;
• X is a methylene group or a sulfur atom;
• Y is a group represented by be following formula (III) or formula (IV);
• and wherein Z is a group represented by the following formula (V), or formula (VI), or a linear or branched lower alkyl group having 6 or less carbon atoms;
• wherein R5 represents a linear or branched lower alkyl group having 1-4 carbon atoms or a halogeno group, R6 represents an amino group or hydroxyl group, R7, R8, and R9 respectively represent a hydrogen atom, methyl group, or fluoro group, R10, R11, R12, R13 and R14 individually represent a linear or branched lower alkyl or alkoxy group having 1-4 carbon atoms, a halogeno group, or a hydrogen atom, R15, R16, R17, R18 and R19 individually represent a linear or branched lower alkyl or alkoxy group having 1-4 carbon atoms, a halogeno group, or a hydrogen atom, and Q represents an alkylene group, n is 1, and m is 0-6.