Dual Catalysis with Copper and Rhenium for Trifluoromethylation of Propargylic Alcohols: Efficient Synthesis of α-Trifluoromethylated Enones

Trifluoromethylation of propargylic alcohols to provide (Z)-alpha-trifluoromethylated enones and beta-unsubstituted alpha-trifluoromethylated enones proceeded with high yield and selectivity in the presence of CuI/Re2O7. The Z isomer was formed under kinetic control, though it is less stable than the E isomer in terms of steric repulsion.