THE KHARASCH REACTION REVISITED - CUX(3)LI(2)-CATALYZED CONJUGATE ADDITION-REACTIONS OF GRIGNARD-REAGENTS

The conjugate addition of Grignard reagents RMgX to alpha,beta-unsaturated ketones and esters is effectively catalyzed by soluble copper ate-complexes of the type CuX(3)Li(2), e.g. CuI . 2LiCl. In the presence of Me(3)SiCl the corresponding ketone enolsilanes are formed in high yield and selectivity. Diasteroselectivity in the case of chiral ketones is similar to that observed by using stoichiometric amounts of cuprates R(2)CuLi. Thus CuX3Li(2)-catalyzed 1,4-additions of Grignard reagents may be an industrially viable process.