Preparation of N-aryl-substituted spiro-beta-lactams via Staudinger cycloaddition

The interest in the study of beta-lactams continues due to their therapeuti c importance as antibiotics. In this work, six spiro-beta-lactams (7a-7c, 8 a-8c) have been prepared using the [2+2] cycloaddition of isomaleimides to acid chlorides. The heterobicyclic structures obtained have been characteri zed by mass spectrometry, IR, NMR spectroscopy, and for compounds 7a, 7b, a nd 8b the X-ray crystallographic study showed a nearly planar arrangement f or the beta-lactam ring.