One-Pot Enantioselective Syntheses of Iminosugar Derivatives Using Organocatalytic anti-Michael−anti-Aza-Henry Reactions

Organocatalyst-controlled asymmetric anti-Michael reactions of (tert-butyldimethylsilyloxy)acetaldehyde with a range of nitroolefins, followed by an intermolecular aza-Henry reaction with imine, provided iminosugar derivatives with five contiguous stereocenters in very high enantiomeric excess in one pot. The stereochemistry of the aza-Henry reaction was substrate controlled and is explained by a six-membered cyclic transition-state model.