Patent ID: 7498452

Claim:
A compound of formula III wherein X is selected from the group consisting of —N 3 , —NH 2 , —NH—R 3 and ═CH—R 8 , R 2 is hydrogen or acyl; R 3 is C 1 -C 4 alkoxycarbonyl or, taken together with R 4 , forms a carbonyl, thiocarbonyl, SO, SO 2 group; R 4 is hydrogen or, taken together with R 3 or R 8 , forms the groups specified in the respective definitions of R 3 and R 8 ; R 5 is hydrogen or an alcohol-protecting group; R 6 is aryl, substituted aryl, heteroaryl; R 8 is hydrogen, C 1 -C 4 alkyl, C 1 -C 4 alkoxycarbonyl or, taken together with R 4 , forms a carbonyl group; R 9 is an acyl or hydroxyaminoacyl group.