A Practical Synthetic Method for 3-(N, N-Disubstituted Carbamoyloxy)-methyl Cephems without Generating the Δ²-Isomers

Abstract

E1101, a new oral caphalosporin, has a (N, N-dimethylcarbamoyloxy)methyl group at the C-3 position of the cephem nucleus. The previous methods for manufacturing 3-(N, N-disubstituted carbamoyloxy)methyl cephems generate various amounts of intractable Δ² isomers as by-products. In this report, we describe a new, practical synthetic method for cephems of this type without generating Δ² isomers, via 7-acylamino-3-(4-nitrophenoxy-carbonyloxy)methyl-Δ³-cephem-4-carboxylic acid (5) as a key intermediate.