Patent ID: 7262298

Claim:
A compound of formula: wherein A is chosen from —C(═O)NH 2 and —C(═S)NH 2 ; R 2 and R 2a are both hydrogen or taken together R 2 and R 2a are ═O; R 3 is chosen from hydrogen, lower alkyl, alkenyl, aryl, heterocyclyl, benzyl and hydroxyalkyl; R 4 is chosen from hydrogen, hydroxy, amino, lower alkoxy, C 1 –C 20 alkyl and C 1 –C 20 alkyl substituted with hydroxy or carbonyl; R 11 is hydrogen; R 12 is chosen from hydrogen, hydroxy, lower alkoxy and —NR 13 R 14 ; or together, R 11 and R 12 form a carbonyl or a vinyl substituent; R 13 and R 14 are chosen independently from hydrogen and C 1 to C 7 hydrocarbon; and the dotted line represents an optional double bond.