Metal iodide mediated ring expansion of cyclopropanecarboxylic thioesters with imines

Metal iodide mediated three-component reactions of cyclopropanecarboxylic thioesters 1, aldehydes, and amines were developed. The initial products, pyrrolidines 2 were obtained in 39–73% yields, which could further be converted to lactams 4, via sequential reactions of a retro-aza-Michael addition and an intramolecular cyclization. This methodology provided facile access to analogs of both pyrrolidines 2 and lactams 4.