Asymmetric Ketone Diene Coupling via Stereodivergent Copper Catalysis.

We report herein the stereodivergent and enantioselective coupling of ketones with dienes. Under the developed conditions, the reactions of 1,3-butadienyltriisopropylsilane with ketones provide syn-(E)-adducts with excellent enantioselectivities via an α-silyl-(Z)-allylcopper intermediate. By contrast, the reactions between 1,3-dienylboronate and ketones involve an α-boryl-(E)-allylcopper intermediate to give anti-(Z)-adducts with excellent optical purity. The stereodivergence and enantioselectivity of the reactions originate from the distinct allylcopper species involved in the ketone addition step. DFT computational studies provide further evidence to support the analyses.