The [(benzyloxy)methyl]( tert-butyl)methylsilyl group was used as the chiral auxiliary to effect highly diastereoselective conjugate additions of oranocuprates to enones. Thus, reaction of several R 2CuLi with α-silylated α,β-unsaturated ketones afforded the respective addition products with π-face selectivities of up to 99%. Starting with an optically active substrate, enantiomerically enriched (−)-( R)-phenyl 2-phenylpropyl ketone was prepared with virtually no loss of chiral information in a reaction sequence involving cuprate addition, hydrolysis, and removal of the silicon group.