Gist-Brocades N.v.

Jan J De Koning

Jan Verweij

Hendrik A Witkamp

Cornelis A Bruynes

Roland P Bezemer

Jagdfish C Kapur

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-cepham derivative with activated metal, preferably zinc or magnesium.

Process for the preparation of 3-exomethylene cepham derivatives

3-Exomethylenecepham sulfoxide derivatives and intermediates therefor, viz. 2-chlorosulfinylazetidin-4-ones are prepared in high yield and purity by reaction of a penam sulfoxide ester with a N-chloro halogenating agent in the presence of molecular sieves.

Preparation of 3-exomethylenecepham sulfoxides and

An improved process for the preparation of 3-bromomethyl-3-cephem sulfoxide derivatives of the formula ##STR1## wherein R.sub.1 is an acylamido group and R.sub.2 is a group protecting the carboxy radical which are valuable intermediates for the preparation of various therapeutically useful cephalosporanic acid derivatives.

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Rijswijk, Netherlands

Jan J De Koning