Transformations of penicillin. Part I. Preparation and rearrangements of 6β-phenylacetamidopenicillanic sulphoxides

Abstract

The isomeric sulphoxides of 6β-phenylacetamidopenicillanic acid esters and N-t-butyl-amides have been prepared. The (R)-sulphoxides can be thermally converted into the (S)-isomers. Deuterium labelling showed that the isomerisation proceeds via a sulphenic acid intermediate. Rearrangement of the sulphoxides with acetic anhydride produces mainly the corresponding acetoxypenams and acetoxycephams. Both isomers of the acetoxy-substituted penam can be formed by isomerisation of the appropriate sulphoxide.