Epoxy ring-opening reactions of endo- and exo-3,4-epoxy-6-azabicyclo[3.2.0] heptan-7-ones
Abstract
The epoxide ring in the β-lactams (2) and (3) was opened regioselectively with aqueous hydroiodic acid; attack by iodide occurred at C-3 preferentially. Thiophenolate ions attacked the epoxy-lactam (2) at C(4) with high selectivity while the epoxide (3) was attacked at C(3) exclusively. The differing selectivities of attack by nucleophiles at the epoxide units are explained in terms of an interplay of steric and electronic impositions owing to the neighbouring β-lactam ring.