Catalytic asymmetric Mannich reaction of glycine Schiff bases with α-amido sulfones as precursors of aliphatic imines.

A general and practical Cu(I)-Fesulphos-catalyzed Mannich reaction of glycinate Schiff bases with aliphatic imines generated in situ from α-amido sulfones is described. Imines with linear and branched alkyl chains, including substrates bearing functional groups, can be efficiently applied. The resulting syn-configured orthogonally protected β-alkyl-α,β-diamino acid derivatives are produced with excellent levels of diastereo- (typically syn/anti >90 : <10) and enantioselectivity (generally ≥90% ee).