| 摘要 |
The present invention provides the compounds of the formula (II): <IMAGE> (II) and pharmaceutically acceptable salts and esters thereof wherein R3 is a hydrogen atom, a group HO3S- or a group R5CO wherein R5 is C1-6 alkyl, C2-6 alkenyl, aryl, aryl(C1-6)alkyl or aryloxy(C1-6)alkyl; and R4 is an organic group other than methyl bonded to the -CO-NH- moiety via a carbon atom; with the proviso that when R3 is a hydrogen atom or a group R5CO the stereochemical configuration at the alpha -carbon atom of the C-6 substituent is S, and with the further proviso that when R3 is a group HO3S- the hydrogen atoms at C-5 and C-6 are cis. Their use is described as are processes for their preparation. Compounds wherein the R4CO- moiety is replaced by a hydrogen atom are also prepared. |
