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

The interest in the study of ?-lactams continues due to their therapeutic importance as antibiotics. In this work, six spiro-?-lactams (7a-7c, 8a-8c) have been prepared using the [2+2] cycloaddition of isomaleimides to acid chlorides. The heterobicyclic structures obtained have been characterized by mass spectrometry, IR, NMR spectroscopy, and for compounds 7a, 7b, and 8b the X-ray crystallographic study showed a nearly planar arrangement for the ?-lactam ring.Key words: ?-lactams, azetidinone, isomaleimides, ketenes, X-ray crystallography.