Catalytic Enantioselective Ynamide Additions to Isatins: Concise Access to Oxindole Alkaloids

The highly enantioselective addition of terminal ynamides to a variety of isatins, catalyzed by a bisoxazolidine copper complex under mild, base‐free reaction conditions, is described. The reaction is broad in scope, scalable, applicable to unprotected isatins and provides efficient access to 3‐hydroxyoxindoles carrying a tetrasubstituted chirality center with excellent yields and enantioselectivities. Synthetically versatile, multifunctional 3‐hydroxyindolinones are obtained via hydration, partial hydrogenation or hydroxyacyloxylation of the ynamide moiety at room temperature and exhaustive hydrogenation followed by reductive detosylation and spontaneous cyclization affords cinchonamidine alkaloids.

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