Formation of enantiomeric 4-oxa-2,6-diazabicyclo[3.2.0]hept-2-en-7-ones from methyl 6α- and 6β-phenoxyacetamidopenicillanates

Abstract

Methyl 6α-phenoxyacetamidopenicillanate was transformed by reaction with chloramine T or (dichloroiodo)-benzene into methyl 3-methyl-2-[(1R,5S)-3-phenoxymethyl-7-oxo-4-oxa-2,6-diazabicyclo[3.2.0]hept-2-en-6-yl]but-2-enoate. The (1S,5R)-isomer was prepared by the reaction of (dichloroiodo)benzene with methyl 6β-phenoxyacetamidopenicillanate. Differences in the reactivities of the 6α- and 6β-acylaminopenicillanates towards chloramine T and (dichloroiodo)benzene are noted.