Reaction of β-lactam carbenes with alkyl isonitriles for a ready approach to 4-cyano and 4-carbamoyl substituted β-lactams

The reaction of β-lactam carbenes with alkyl isonitriles was investigated. Two different types of products, 4-cyano- or 4-carbamoyl-β-lactams, were isolated, depending upon the nature of the alkyl group of the isonitriles. The cyano-β-lactams were derived by a N-to-C 1,3-rearrangement of the ketenimine intermediates, while the carbamoyl-β-lactams were the hydrolysis products of the intermediates. This work extends the application of β-lactam carbenes, and provides a very simple and efficient route to 4-cyano- or 4-carbamoyl-β-lactams, which are versatile synthetic intermediates and new chemical entities of potential biological activity.