Copper-Catalyzed Enantioselective 1,6-Boration of para-Quinone Methides and Efficient Transformation of gem-Diarylmethine Boronates to Triarylmethanes

Presented is the first enantioselective copper-catalyzed 1,6-conjugate addition of bis(pinacolato) diboron to para-quinone methides. The reaction proceeds with excellent yields and good to excellent enantioselectivities, and provides an attractive approach to the construction of optically active gem-diarylmehtine boronic esters. Additionally, the subsequent conversion of the derived potassium trifluoroborates into triarylmethanes with highly enantiospecificity was realized.