Synthesis of αβ-Unsaturated Trifluoromethyl Ketones from 4-Dimethylamino-1,1,1-trifluorobut-3-ene-2-one by Addition of Grignard Reagents

Enaminones are available by reaction of 4-ethoxy-1,1,1-trifluorobut-3-ene-2-one with amines such as dimethylamine and they react with Grignard reagents to give αβ-unsaturated trifluoromethyl ketones in good yield by 1,4-addition followed by elimination. The generality of this procedure is contrasted with reactions based either on the use of organolithium nucleophiles, or the use of 4-alkoxy-αβ-unsaturated trifluoromethyl ketones as electrophilic partners.