Patent ID: 8377953

Claim:
A compound of formula I: wherein: X is S, N or NR 5 and Y is N or NR 5 , with the proviso that one, but not both, of X or Y is N; R 1 and R 3 are, independently, hydrogen, or optionally substituted alkyl, alkenyl, alkynyl, heterocyclyl, trialkylsilyl, arylalkyl, aryloxyalkyl, aryl or heteroaryl, with the proviso that they are not both hydrogen; R 2 is optionally substituted 5- or 6-membered heteroaryl; R 4 is hydrogen or acyl; R 5 is hydrogen or optionally substituted alkyl, alkenyl, alkynyl, heterocyclyl, trialkylsilyl, arylalkyl, aryloxyalkyl, arylthioalkyl, aryl or heteroaryl; or a salt or N-oxide thereof.