SYNTHESIS, NMR, AND CONFORMATIONAL STUDIES OF SOME 1,2-LINKED AND 1,3-LINKED DISACCHARIDES

Eight 1,2- and 1,3-linked disaccharides have been synthesized in which the glycosidic linkages have different stereochemical environments. 1H and 13C NMR studies and conformational analysis, using the HSEA-approach, indicate a number of proton-oxygen and proton-proton interactions, resulting, inter alia, in downfield and upfield shifts of signals from protons involved in the glycosidic linkages and upfield shifts of signals from carbons which have their protons in γ-gauche contact. The differences of glycosylation shifts induced by a mannopyranosyl versus a glucopyranosyl group have been investigated.