New Efficient Method for the Stereoselective Synthesis of (alpha)-(Trifluoromethyl)-(alpha), (beta)-unsaturated Amides. Lewis Acid-Catalyzed Reaction of 3,3,3-Trifluoro-1-propynylamine with Carbonyl Compounds

N,N-Dibutyl-(3,3,3-trifluoro-1-propynyl)amine, prepared readily by the dehydrofluorination of N,N-dibutyl-(2,2,3,3,3pentafluoropropyl)amine with lithium diisopropylamide at room temperature, smoothly reacted with a variety of aldehydes and ketones in the presence of a catalytic amount of Lewis acid and molecular sieves 4A at ambient temperature to give the corresponding (alpha)-(trifluoromethyl)-(alpha),(beta)-unsaturated amides in good to excellent yields with high Z stereoselectivity.