Diastereo- and Enantioselective Copper-Catalyzed DecarboxylativeRing-Opening [3 + 2] Annulationof Tertiary Propargylic Carbamates through Regioselective α‑Attackof γ‑Butenolides

A copper-catalyzed regio-, diastereo-, and enantioselective decarboxylative ring-opening [3 + 2] annulation of tertiary propargylic carbamates with γ-butenolides for the synthesis of optically active pyrrolidinones has been realized. The reaction proceeded through regioselective α-attack of γ-butenolide and generated highly congested vicinal tertiary and all-carbon quaternary stereocenters in pyrrolidinone scaffolds, featuring high stereoselective induction and broad functional group tolerance. Critical to the successful development of this method was the employment of copper catalysis in concert with a diPh-Pybox ligand.