| 摘要 |
<p>Intermediates in the production of cephalosporins of formula (IA) wherein either α) Ra denotes hydrogen or a silyl group; Rb denotes a group of formula -ORe, wherein Re denotes hydrogen or alkyl; and R?c and Rd¿ together denote a bond; or β) R?d and Ra¿ denote hydrogen or a silyl group; and R?b and Rc¿ together denote an imino group of formula = N-Y, wherein Y denotes alkyl, aryl or heterocyclyl; or η) Rd denotes hydrogen or a silyl group; Ra denotes hydrogen, if Rd denotes hydrogen; or, Ra denotes hydrogen or a silyl group, if Rd denotes a silyl group; and R?b and Rc¿ together denote the oxo group; in free form or in salt form.</p> |
