Synthesis of a 7-oxo-1,4-diazabicyclo[3.2.0]hept-3-ene-2-carboxylate (Δ1-azapenem) and a related 3,7-dioxo-1,4-diazabicyclo[3.2.0]heptane-2-carboxylate, a fused β,γ-lactam

Abstract

The Δ¹-azapenem (3) is synthesised by cyclisation of the azetidinone isothiocyanate (7) followed by S-alkylation; the intermediate 7-oxo-3-thioxo-1,4-diazabicyclo[3.2.0]heptane-2-carboxylate (8) can be oxidised by benzeneseleninic anhydride to give a fused β,γ-lactam.