A Homodinuclear Mn(III)2-Schiff Base Complex for Catalytic Asymmetric 1,4-Additions of Oxindoles to Nitroalkenes

Catalytic asymmetric 1,4-additions of 3-substituted oxindoles to beta-aryl, beta-heteroaryl, and beta-alkenyl nitroalkenes are described. A new homodinuclear Mn-2(OAc)(2)-Schiff base 1 complex was required to realize high diastereo- and enantioselectivity. Mn-2(OAc)(2)-1 (1-5 mol %) promoted the 1,4-additions in 99-83% yield, 96-85% ee, and >30:1-5:1 dr at room temperature, providing useful chiral building blocks for the synthesis of beta-aminooxindoles with vicinal quaternary/tertiary carbon stereocenters.