Degradation of penicillin sulphoxide.

The thesis describes three principle investigations of the alkaline and enzymic degradation of penicillin V beta-sulphoxide. (i) Penicillin V beta-sulphoxide was observed to undergo epimerisation at C-6 on treatment with mild aqueous base: the direct epimerisation of the sulphoxide has only previously been observed using esters in non-aqueous solutions. (ii) 3-phenoxyacetamido-1-phenoxyacetylpyrrole was isolated as an alkaline hydrolysis product of VSO: this appears to be the first reported example of the direct degradation of a penicillin derivative to a pyrrole. This compound was then synthesised and compared with the isolated product. (iii) Comparative studies of the degradation of penicillin V sulphoxide by beta-lactamase and alkali indicated the possible operation of different pathways: this contrasts with the corresponding degradations of penicillin V which were indistinguishable. These investigations are discussed in the context of earlier studies of beta-lactam degradation which are reviewed in an introductory chapter