Gist-brocades N.v.

Gerardus J Van Veen

Jan Verweij

Peter W Henniger

Herman H Grootveld

Henri G Hirs

Jan Kalter

A process for the preparation of 7.beta.-acylamino-3-substituted-3-cephem-4-carboxylic acid compounds comprising reacting at -70.degree. C. to 0.degree. C. in an inert organic solvent phosphorus pentachloride with a cephalosporin compound in the presence of an olefinic compound having at least one carbon-carbon double bond having not more than three hydrogen atoms attached thereto capable of removing chlorine at least in part by addition to a carbon-carbon double bond.

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Zoetermeer, Netherlands

Gerardus J Van Veen