Enantioselective synthesis of α-substituted ketones by asymmetric addition of chiral zinc enamides to 1-alkenes
A zinc enamide of a chiral imine derived from a ketone and (S)-valinol or (S)-t-leucinol undergoes addition to 1-alkene to generate a γ-zincioimine intermediate, which reacts with a carbon electrophile to give upon hydrolysis an optically active α-substituted ketone in good yield. The stereoselectivity of the addition reaction may reach 99% for the reaction of a cyclohexanone imine with ethylene. Copyright