Brønsted Acid-Catalyzed, Enantioselective, Vinylogous Mannich Reaction of Vinylketene Silyl N,O-Acetals

Abstract

Vinylketene silyl N, O-acetals undergo chiral phosphoric acid-catalyzed, vinylogous Mukaiyama-Mannich reactions with imines and afford delta-amino-alpha,beta-unsaturated amides in typically good yields, complete gamma-regioselectivity, and up to 92% ee with catalyst loadings of as low as 1 mol %. The Mannich products can be readily manipulated to furnish valuable synthetic intermediates.