A novel, highly stereoselective intermolecular cycloaddition reaction of simple and enantiopure cyclic nitrones to glucose and galactose-derived 1,2-glycals offers a direct access to a new class of pseudoaza-C-disaccharides with isoxazolidine structure, potential glycosidase inhibitors. The synthesis of new (1-->2)-linked aza-disaccharides is accomplished by simple reductive ring-opening of the isoxazolidine. (C) 1997 Elsevier Science Ltd.