Alkyl and aryloxyacetaldehydes add enantioselectively to various nitroalkenes. Addition products were isolated in good yield and high enantiomeric purity (up to 96 % ee) but only mediocre synlanti ratios were achieved. The course of the reaction was investigated by mass spectrometry and by DFT calculations.
One-Pot Enantioselective Syntheses of Iminosugar Derivatives Using Organocatalytic <i>anti</i>-Michael−<i>anti</i>-Aza-Henry Reactions
作者:Ritsuo Imashiro、Hisatoshi Uehara、Carlos F. Barbas
DOI:10.1021/ol102292a
日期:2010.11.19
Organocatalyst-controlled asymmetric anti-Michael reactions of (tert-butyldimethylsilyloxy)acetaidehyde 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.