Patent ID: 7045524

Claim:
A compound of Formula (IA) or (IB): in which: R 1 is OR 5 or NR 6 R 7 ; R 2 is vinyl or ethyl; R 3 is H, OH or F; and R 4 is H; or R 3 is H and R 4 is F; in which: R 5 is (C 1-6 ) alkyl; and either: R 6 is hydrogen, [(C 1-4 )alkyl or optionally substituted aryl]; and R 7 is aminoalkyl, azabicyclooctyl, or an aryl (C 1-4 )alkyl group which may be substituted by C 1-6 alkoxy; or R 6 and R 7 , together with the nitrogen atom to which they are attached, form a piperazine ring which may be substituted by aryl, C 1-6 alkyl, or aryl(C 1-4 alkyl); or a pharmaceutically acceptable salt thereof.