Patent ID: 8110566

Claim:
A compound of formula I or a pharmaceutically acceptable salt thereof in which R 1 represents H, fluoro, chloro, bromo, cyano, a C 1-3 alkyl group optionally substituted by one or more fluoro, or a C 1-2 alkoxy group optionally substituted by one or more fluoro; A represents O or S; R 2 and R 3 independently represent H, fluoro, chloro, bromo, a C 1-4 alkyl group optionally substituted by one or more fluoro, or a C 1-4 alkoxy group optionally substituted by one or more fluoro; provided that R 2 and R 3 are not located meta to each other; R 4 and R 5 independently represent H or a C 1-4 alkyl group; and X and Y independently represent O or CH 2 with the proviso that X and Y are different.