Nickel‐Catalyzed Regioselective Three Component Coupling Reaction of Alkyl Halides, Butadienes, and Ar‐M (M=MgX, ZnX)

Abstract
A new method for the regioselective three component cross‐coupling reaction of alkyl halides, 1,3‐butadienes, and aryl‐Grignard reagents has been developed by the use of a nickel catalyst. This reaction proceeds efficiently at 25 °C using (dppf)NiCl2 as a catalyst. Alkyl chlorides, bromides, and iodides can be used as suitable alkylating reagents. The reaction also proceeds when arylzinc halides are used instead of Grignard reagents. Competitive reactions of a mixture of primary, secondary, and tertiary alkyl bromides showed that the reactivities of the halides increase in the order primary<secondary<tertiary. A possible reaction pathway involving single electron transfer from a nickelate complex to alkyl halides is proposed.