Patent ID: 7572797

Claim:
A compound of formula (I): or a pharmaceutically acceptable salt thereof; wherein R 1 is a 5-membered heteroaryl group comprising either (a) from 1 to 4 nitrogen atoms or (b) one oxygen or one sulphur atom and 0, 1 or 2 nitrogen atoms, optionally each independently substituted by one or more substituents selected from (C 1 -C 4 )alkyl, (C 1 -C 4 )alkoxy, halo(C 1 -C 4 alkyl, (C 1 -C 4 )alkoxy(C 1 -C 4 alkyl, amino(C 1 -C 4 )alkyl, amino, (C 1 -C 4 )alkylamino, di-((C 1 -C 4 )alkyl)amino, (C 1 -C 4 alkylamino(C 1 -C 4 )alkyl and di-((C 1 -C 4 alkyl)amino(C 1 -C 4 alkyl; with the proviso that R 1 is not imidazolyl, oxazolyl or 1,2,4-triazolyl; Ar is and → indicates the point of attachment to the pyrazine ring; and each R 2 is independently selected from hydrogen, (C 1 -C 4 alkyl, (C 1 -C 4 alkoxy, halo(C 1 -C 4 )alkyl, halo(C 1 -C 4 alkoxy, cyano and halo.