Patent ID: 8048898

Claim:
A compound represented by formula (I) or a pharmaceutically acceptable salt thereof: wherein Y 1 represents a nitrogen atom or a group represented by CR A , Y 2 represents a nitrogen atom or a group represented by CR B , Y 3 represents a nitrogen atom or a group represented by CR c , provided that one of Y 1 , Y 2 and Y 3 is nitrogen and the other two are carbon, R A , R B and R C , which may be the same or different, each represent a hydrogen atom or a C 1 -C 6 alkyl group (excluding the case where Y 1 is CR A , Y 2 is CR B and Y 3 is CR C ), X represents an oxygen atom, a sulfur atom, a group represented by the formula —SO—, a group represented by the formula —SO 2 —, or a group represented by the formula —NR 6 — (wherein R 6 represents a hydrogen atom or a C 1 -C 6 alkyl group), R 1 represents a C 1 -C 6 alkyl group, or a benzyl group, R 2 represents a hydrogen atom, a C 1 -C 6 alkyl group, or a C 3 -C 8 cycloalkyl group, R 3 represents (i) a C 1 -C 6 alkyl group which may be substituted with 1 to 3 substituents selected from the group A [wherein the group A consists of a halogen atom, a phenyl group, a C 1 -C 6 alkoxy group, an amino group which may be substituted with one or two C 1 -C 6 alkyl groups, a morpholino group, and a piperazino group which may be substituted with a C 1 -C 6 alkyl group(s)], (ii) a C 3 -C 8 cycloalkyl group, or (iii) a phenyl group, a naphthyl group or an isoquinolinyl group, each of which may be substituted with 1 to 3 substituents selected from the group B [wherein the group B consists of a halogen atom, a C 1 -C 6 alkyl group, a C 1 -C 6 alkoxy group, an amino group which may be substituted with one or two C 1 -C 6 alkyl groups, a morpholino group, a piperazino group which may be substituted with a C 1 -C 6 alkyl group(s), a C 1 -C 6 alkanoylamino group, and a C 1 -C 6 alkylsulfonylamino group], R 4 represents a hydrogen atom or a C 1 -C 6 alkyl group, and R 5 represents a phenyl group, a thienyl group, a thiazolyl group, a pyridyl group, a naphthyl group, an indanyl group, a dihydrobenzofuranyl group, a benzodioxolyl group, a benzothiadiazolyl group, a benzothienyl group or a quinolinyl group, each of which may be substituted with 1 to 5 substituents selected from the group C [wherein the group C consists of a C 1 -C 6 alkyl group, a halogen atom, a trifluoromethyl group, a C 1 -C 6 alkoxy group, a trifluoromethoxy group, a nitro group, a cyano group, and a C 2 -C 7 alkanoyl group], or a C 2 -C 8 alkenyl group which may be substituted with a phenyl group(s).