Copper(I) iodide dimethyl sulfide catalyzed 1,4-addition of alkenyl groups from alkenyl-alkylzincate reagents

The presence of catalytic quantities of the copper(I) iodide dimethyl sulfide complex {(CuI)4(SMe2)3} with alkenyl-alkylzincate reagents allows for the complete chemoselective 1,4-addition of various alkenyl groups to a number of α,β-unsaturated carbonyl compounds in CH2Cl2 at +35 °C. The 1,4-addition of the mixed vinylzincate reagent is more efficient than the corresponding vinylzirconocene reagent in CH2Cl2 or THF. By employing CH2Cl2 as a medium, the asymmetric copper-catalyzed addition of the vinyl groups to α,β-unsaturated imides is facilitated by the presence of TMSOTf to give excellent yields and up to 95:5 diastereomeric ratios (dr).