Nickel/N-Heterocyclic Carbene Complex-Catalyzed Enantioselective Redox-Neutral Coupling of Benzyl Alcohols and Alkynes to Allylic Alcohols

The nickel-catalyzed enantioselective redox-neutral coupling of alcohols and alkynes to access chiral allylic alcohols is reported. The reaction proceeds via a hydrogen transfer process under ambient temperature, converting abundant feedstock alcohols and alkynes to chiral allylic alcohols with high stereoselectivities in one chemical step. Key to the success of this process was the development of a bulky chiral N-heterocyclic carbene, (R,R,R,R)-SIPE, a chiral version of SIPr, as the ligand for nickel. Notably, we found that the utilization of P(OPh)3 as secondary ligand for nickel was crucial to inhibit the isomerization of products.