Chemo- and Enantioselective Arylation and Alkenylation of Aldehydes Enabled by Nickel/N-Heterocyclic Carbene Catalysis

Herein, we report the first highly enantioselective Ni-catalyzed arylation and alkenylation of simple aldehydes using readily available and stable organoboronic esters. This protocol provides various chiral secondary alcohols in high yields and enantioselectivities (up to 97% ee) with a broad scope of substrates, functional groups, and heterocycles. The use of a bulky N-heterocyclic carbene (NHC) ligand for nickel catalyst is the key to high enantiocontrol. The competitive Ni-catalyzed transformations, including Tishchenko reaction, dehydrogenation/hydrogenation reaction, and Suzuki-Miyaura couplings, are avoided. The excellent chemoselectivity is likely due to the application of mild base CsF and eta(2)-coordination of aldehydes with nickel. [GRAPHICS] .