Cu(I)−NHC-Catalyzed (2 + 3)-Annulation of Tetramic Acids with 2H‑Azirines: Stereoselective Synthesis of Functionalized Hexahydropyrrolo[3,4‑b]pyrroles

Abstract

A stereoselective and high-yield synthesis of hexahydropyrrolo[3,4-b]pyrroles from tetramic acids and 2H-azirines under Cu(I)−NHC catalysis is developed. An unusual N−C2 azirine bond cleavage, initiated by a copper enolate, was rationalized in terms of a free radical reaction mechanism.