CEPHALOSPORIN SYNTHESIS

摘要

Intermediates in the production of cephalosporins of formula (IA) wherein either alpha ) R denotes hydrogen or a silyl group; R denotes a group of formula -OR, wherein R denotes hydrogen or alkyl; and R and R together denote a bond; or beta ) R and R denote hydrogen or a silyl group; and R and R together denote an imino group of formula = N-Y, wherein Y denotes alkyl, aryl or heterocyclyl; or gamma ) R denotes hydrogen or a silyl group; R denotes hydrogen, if R denotes hydrogen; or, R denotes hydrogen or a silyl group, if R denotes a silyl group; and R and R together denote the oxo group; in free form or in salt form.