Olivanic acid analogues. Part 7. Lead tetra-acetate oxidation of 3-alkylthio-7-oxo-1-azabicyclo[3.2.0]heptane-2-carboxylates

Abstract

Lead tetra-acetate oxidation of alkylthiocarbapenams (2)–(4) gave α-acetoxy sulphides (5)–(7) with inversion of stereochemistry, Iodosobenzene diacetate was also an effective oxidant. Oxidation to sulphone and elimination of alkanesulphinic acid provided the 3-acetoxy-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate system (13). Alternatively, elimination of acetic acid from compounds (5) or (6) with DBU furnished a new route to alkylthiocarbapenems.