Asymmetric Dearomatization of 3H-Indoles via Copper-Catalyzed Enantioselective [4 + 1] Spiroannulation with Vinyl Ethynylethylene Carbonates

We herein report a novel copper-catalyzed asymmetric dearomative [4 + 1] spirocyclization of 3H-indoles with vinyl ethynylethylene carbonates. This transformation proceeds through a highly chemo-, regio-, and enantioselective nucleophilic addition/intramolecular annulation cascade of a reactive copper vinylallenylidene intermediate, delivering a series of valuable spiroindolenine derivatives featuring a chiral quaternary stereocenter with excellent efficiency.