Compounds for the preparation of cephem derivatives.

摘要

The invention provides specific compounds being useful for the preparation of cephem derivatives of the following formula: wherein R1 means a fluorine-substituted lower alkyl and A1 denotes a cyclic or acyclic ammonio group, or a non-toxic salt thereof. These specific compounds are given by the formulae wherein R7 means a lower alkyl group, or a salt thereof.h