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

The first catalytic enantioselective γ-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 γ,γ-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.