Direct Catalytic Asymmetric Vinylogous Mannich-Type and Michael Reactions of an α,β-Unsaturated γ-Butyrolactam under Dinuclear Nickel Catalysis

Direct catalytic asymmetric vinylogous reactions of an alpha,beta-unsaturated gamma-butyrolactam as a donor are described. A homodinuclear Ni-2-Schiff base complex promoted a vinylogous Mannich-type reaction of N-Boc imines as well as a vinylogous Michael reaction to nitroalkenes selectively at the gamma-position under simple proton-transfer conditions. Vinylogous Mannich adducts were obtained in 5:1 -> 30:1 dr and 99% ee, and vinylogous Michael adducts were obtained in 16:1 -> 30:1 dr and 93-99% ee.