Copper‐Catalyzed Enantioselective Conjugate Addition of Grignard Reagents to α,β‐Unsaturated Esters

Stable dinuclear Cu complexes have been used to catalyze the conjugate addition of inexpensive and readily available Grignard reagents to acyclic α,β-unsaturated esters. The method provides the corresponding β-substituted optically active esters in high yields and with excellent enantioselectivities (see scheme). R3=cyclohexyl, R4=Ph or R3=Ph, R4=cyclohexyl.