Novel synthesis of 3-pyrrole substituted β-lactams via microwave-induced bismuth nitrate-catalyzed reaction

Highly stereoselective synthesis of 3-pyrrole substituted beta-lactams is accomplished. The first step involves the synthesis of 3-phthalimido substituted beta-lactams following Staudinger cycloaddition reaction of acid chloride equivalent with imines. Synthesis of 3-amino beta-lactams is achieved via the deprotection of phthalimido group with ethylenediamine. These 3-amino beta-lactams are converted to a new series of N-substituted pyrroles at room temperature as well as using microwave-induced bismuth nitrate-catalyzed reaction with an excellent yield. Exclusive formation of trans pyrrole-substituted beta-lactams is observed with N-chrysenyl system. The method is equally efficient for the synthesis of racemic as well as optically pure 3-pyrrole substituted beta-lactams. (C) 2012 Elsevier Ltd. All rights reserved.