New approaches to β-trifluoromethylated enone derivatives

beta-Trifluoromethylated enaminones 1 were prepared stereospecifically or high stercoselectively in 31-92% yields from the reaction of Weinreb amides with trifluoropropynyl lithium, followed by quenching with H(2)O in the presence of amine derivatives. beta-Trifluoromethylated enaminone 1a was reacted with aryl or alkynyl Grignard reagents to give Michael addition products 5 at 0 degreesC, whereas addition-elimination adducts, beta-aryl (or alkynyl)-beta-trifluoromethylated enones 6, were obtained stereospecifically in 50-92% yields after stirring at room temperature for several hours. (C) 2004 Elsevier B.V. All rights reserved.