Stereoselective syntheses of chiral heterocycles and alkaloids using carbohydrate auxiliaries

N-Glycosyl imines show an efficient diastereofacial differentiation in thei r reactions with nucleophiles. Coordination to suitable Lewis acids enhance s this effect, which is demonstrated in the enantioselective syntheses of a lpha-amino acids, homoallylamines and beta-amino acids. Asymmetric aza Diel s-Alder and tandem Mannich-Michael reactions have been applied for the enan tioselective synthesis of chiral piperidine derivatives including alkaloids , e.g. anabasin, gephyrotoxin 167B, pumiliotoxin C and its 4a-epimer.