Sulfur- and Base-Promoted Access to γ-Thiolactams from Benzoins and Cyanoacetates

Despite the synthetic importance of γ-thiolactams, efficient methods to construct them from simple precursors using elemental sulfur remain elusive. We describe a base-catalyzed, one-step multicomponent reaction to access γ-thiolactams from readily available benzoins, active acetonitriles, and elemental sulfur, a clean, economical, and convenient sulfur source. The transformation proceeds under mild conditions to yield diverse γ-thiolactams in good to excellent yields with excellent functional group tolerance. Notably, substrate activation with a cyclizable primary or secondary amide group directs the cyclization through the amide moiety, leaving the nitrile untouched and providing straightforward access to γ-lactams.