Preparation of N‐Glycosylhydroxylamines and Their Oxidation to Nitrones for the Enantioselective Synthesis of Isoxazolidines

N‐benzyl‐ and N‐methyl‐N‐glycosylhydroxylamines 3a−i were conveniently obtained by reaction of sugars with N‐substituted hydroxylamines according to a novel procedure. Subsequent oxidation occurred at the alkyl group, selectively affording the corresponding C‐phenyl‐ and C‐unsubstituted N‐glycosylnitrones. C‐phenyl‐N‐glycosylnitrones 10 and 13 underwent highly stereoselective 1,3‐dipolar cycloaddition with dimethyl maleate, with the sugar moiety acting as a chiral auxiliary. Final removal of the glycosyl moiety afforded enantiopure enantiomeric isoxazolidines 17 and ent‐17 which are oxa‐analogues of proline diester derivatives. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)