Patent ID: 8377922

Claim:
A compound represented by the following structural formula (I): wherein R 1 represents a C 1 -C 6 alkyl group or a halogeno C 1 -C 6 alkyl group, R 2 is a carboxyl group which may be substituted by a C 1 -C 12 alkyl group, C 7 -C 18 aralkyl group, C 1 -C 2 alkyl group substituted by a C 2 -C 5 alkanoyloxy group, C 1 -C 2 alkyl group substituted by a (C 1 -C 4 alkoxy)carbonyloxy group, N,N-dimethylaminocarbonylmethyl group, 2-(morpholin-4-yl)ethyl group, (5-methyl-2-oxo-1.3-dioxolen-4-yl)methyl group or (5-phenyl-2-oxo-1,3-dioxolen-4-yl)methyl group, and Y represents the formula (II): wherein Z represents CH or a nitrogen atom, or a pharmaceutically acceptable salt thereof.