Mild Synthesis of β‐Amino‐α,α‐difluoro Ketones from Acylsilanes and Trifluoromethyltrimethylsilane in a One‐Pot Imino Aldol Reaction

Abstract β‐Amino‐α,α‐difluoro ketones have been very conveniently prepared in a one‐pot procedure from acylsilanes, trifluoromethyltrimethylsilane and imines. The key intermediate in this reaction is a difluoroenoxysilane. The Lewis acid promoted imino aldol reaction was performed with BF3·OEt2 or under very mild conditions using a catalytic amount of Yb(OTf)3. The reaction with chiral benzylimines occurred in good yield with 52–78 % de. Palladium‐catalyzed hydrogenolysis furnished an unprotected β‐amino‐α,α‐difluoro ketone or a β‐amino‐α,α‐difluoro alcohol. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)