A Copper(I)-Catalyzed Enantioselective -Boryl Substitution of Trifluoromethyl-Substituted Alkenes: Synthesis of Enantioenriched gamma,gamma-gem-Difluoroallylboronates

The first catalytic enantioselective -boryl substitution of CF3-substituted alkenes is reported. A series of CF3-substituted alkenes was treated with a diboron reagent in the presence of a copper(I)/Josiphos catalyst to afford the corresponding optically active ,-gem-difluoroallylboronates in high enantioselectivity. The thus obtained products could be readily converted into the corresponding difluoromethylene-containing homoallylic alcohols using highly stereospecific allylation reactions.