A novel heterocycloaddition merges 2-thiono-3-ketolactones with carbohydrate glycals to afford materials which resemble disaccharides with an O-glycosidic linkage at the anomeric center and a thioether linking both C-2 and C-2′, thus creating a third heterocyclic ring. Upon desulfurization, these novel cycloadducts afford materials which are models for 2- deoxydisaccharides. Studies with two keto lactones and seven glycals are described.