Copper-Catalyzed Domino Bis-[3 + 2]-Annulation of Ethynyl Cyclic Carbonates with Trifluoromethyl Azlactones.

Herein, we introduce a novel bis-annulation of ethynyl cyclic carbonates with trifluoromethyl azlactones, enabling the assembly of a pyrrolidine-fused lactone containing two quaternary-bridged stereocenters. The reaction proceeds through two [3 + 2]-annulations in a domino mode involving decarboxylative propargylation/lactone formation/aza-annulation reactions with high diastereoselectivity. Interestingly, the scope was extended to ethynyl cyclic carbamates to construct pyrrolidine-fused lactams. This protocol reveals the utility of three reactive sites of both precursors in a single operation for the first time. Further, the scale-up and diverse transformations of the product highlighted its synthetic utility.