Enantioselective Addition of Boronates to o-Quinone Methides Catalyzed by Chiral Biphenols

Chiral biphenols were found to catalyze the enantioselective asymmetric addition of aryl- or alkenylboronates to o-quinone methides. Substituted 2-styryl phenols were obtained in good yields (up to 95%) with high enantiomeric ratios (up to 98:2) in the presence of 10 mol % 3,3'-Br-2-BINOL. A two-step synthesis of (S)-4-methoxydalbergione in good yield and selectivity was achieved.