Process for the preparation of 3-exomethylene cepham derivatives
申请人:Gist-Brocades N.V.
公开号:US04985554A1
公开(公告)日:1991-01-15
A process is provided for the preparation of 3-methylene and 3-halomethylene cepham derivatives via 3-phosphoniomethyl-3-cephem derivatives, which in turn can be prepared from 3-halomethyl-3-cephem derivatives. The preparation can be carried out with or without isolating the intermediate phosphonium cephem compounds. The 3-methylene and 3-halomethylene cepham derivatives and in particular the 1-oxo and 1,1-dioxo cepham compounds are also prepared by reducing a 3-halomethyl-3-cephem derivative with activated metal, preferably zinc or magnesium.