Gold/Chiral Amine Relay Catalysis Enables Asymmetric Synthesis of C2-Quaternary Indolin-3-ones.

A mild and effective strategy for the asymmetric synthesis of C2-quaternary indolin-3-ones from 2-alkynyl arylazides and ketones by gold/chiral amine relay catalysis is described. In this reaction, 2-alkynyl arylazides undergo gold-catalyzed cyclization, nucleophilic attack, and oxidation to form intermediate 2-phenyl-3H-indol-3-ones, followed by an l-proline-catalyzed asymmetric Mannich reaction with ketones, to afford corresponding products in satisfactory yields with excellent enantio- and diastereoselectivities.