| abstract |
A compound represented by formula (I-A): **(See formula)** wherein R1 represents a C1-6 alkyl group, a heteroaryl group optionally substituted with a halogen atom or the following formula (IIIA): **( See formula)** where Rx represents a hydrogen atom, a halogen atom, a C1-6 alkyl group or a C1-6 alkoxy group, wherein the C1-6 alkyl group and the C1-6 alkoxy group are each one optionally substituted with one to three halogen atoms, and Ry represents a hydrogen atom, a fluorine atom, a C1-6 alkyl group or a C1-6 alkoxy group, wherein the C1-6 alkyl group and the alkoxy group C1-6 are each optionally substituted with one to three halogen atoms, R1' represents a hydrogen atom or a C1-6 alkyl group, or R1 and R1' optionally form a C3-8 cycloalkane together with the adjacent carbon atom thereto, R2 represents a C3-6 alkyl group, a C3-8 cycloalkyl group optionally substituted with one to three C1-6 alkyl groups, a C3-8 cycloalkoxy group optionally substituted with one to three C1-6 alkyl groups and optionally having a C1-5 alkylene group crosslinking two different carbon atoms in the ring, an adamantyl group optionally substituted with one to three C1 alkyl groups -6, or a phenyl group, R3 represents a hydrogen atom or a C1-6 alkyl group, and R4 represents a hydrogen atom or a fluorine atom, or a pharmaceutically acceptable salt thereof. |