Catalytic Asymmetric Nazarov Cyclization of Heteroaryl Vinyl Ketones through a Crystallographically Defined Chiral Dinuclear Nickel Complex

A Ni(NTf2)(2) and tetradentate bisimino-bisquinoline ligand complex catalyzed the enantioselective Nazarov cyclization of heteroaryl vinyl ketones. An X-ray-quality crystal was obtained from a mixture of the Ni complex and the substrate, which was the dinuclear chiral Ni complex. From information regarding the structure of the complex, the substrate was distorted to form a helical shape, and the carbon atoms involved in bond formation were close to each other. In addition, mechanistic studies revealed that the configuration of the olefin moiety was isomerized before bond formation.