Catalytic asymmetric direct Mannich-type reactions of α-substituted nitroacetates using a new bench-stable homodinuclear Ni2-Schiff base 1b complex are described. The Ni2-1b complex gave Mannich products, precursors for anti-α,β-diamino acids with an α-tetrasubstituted carbon stereocenter, in >99-91% ee. The Ni2-1b complex was also applicable to direct Mannich-type reactions of malonates and β-keto ester, giving products in high stereoselectivity (up to 99% ee, dr >97:3). Preliminary mechanistic studies suggested that the dinuclear Ni metal centers had key roles to achieve good reactivity and high stereoselectivity.
All Science Journal Classification (ASJC) codes
- 化学 (全般)