Catalytic enantioselective conjugate addition of Grignard reagents to cyclic α,β-unsaturated carbonyl compounds

A catalytic asymmetric conjugate addition reaction of organocopper reagents, generated from copper salt, a chiral phosphine, and Grignard reagent, with cyclohexenone is highly dependent on the counter anion of copper species, solvents, Grignard reagents, and the structure of the chiral phosphine. The reaction using the combination of 8 mol% of copper iodide, 32 mol% of the amidophosphine 3, and 1.2 equiv of organomagnesium chloride with cyclohexenone in ether at -78 degrees C gave the 3-substituted cyclohexanone in up to 92% ee and 90% yield. (C) 1999 Elsevier Science Ltd. All rights reserved.