Stereodivergent syntheses of altro and manno stereoisomers of 2-acetamido-1,2-dideoxynojirimycin

Abstract

A stereoselective synthesis of 2-acetamido-1,2-dideoxyaltronojirimycin (8) and its manno epimer 9 is described. The synthetic approach is based on key bicyclic carbamate 7, which is easily accessible with high enantiomeric purity on a multigram scale by Sharpless asym. epoxidn. of 1,4-pentadien-3-ol or 2,4-pentadien-1-ol. This procedure completes an efficient stereodivergent approach to five isomers of 2-acetamido-1,2-dideoxyiminosugars in high overall yields starting from the same key intermediate 7. The approach described in this paper is based on control of the stereoselectivity of the sulfite ring-opening reaction to give retention of configuration through anchimeric assistance from the endocyclic amine.