PROCESS FOR PRODUCING 7-SUBSTITUTED-3-CEPHEME-4-CARBOXYLIC ACID DERIVATIVES

摘要

Cephem compounds of the formula: …… wherein R<1> is amino or a protected amino,… R<2> is lower alkyl,… R<3> is hydrogen or lower alkyl,… R<4> is hydrogen, acyloxy(lower)alkyl, acylthio(lower)alkyl or a heterocyclicthio(lower)alkyl which may be substituted with suitable substituent(s) and… R<5> is carboxy or a protected carboxy, and… pharmaceutically acceptable salt thereof and process for their preparation, and also a pharmaceutical composition comprising, as an effective ingredient, the above compound in association with a pharmaceutically acceptable, substantially non-toxic carrier or excipient. The invention also relates to the starting compounds …… and their preparation.