Synthesis of and nuclear magnetic resonance and conformational studies on some 1,2-linked disaccharide methyl glycosides containing D-mannose and L-rhamnose

Abstract

Syntheses have been performed of eight 1,2- linked disaccharide methyl glycosides in which the glycosidic linkages have different stereochemical surroundings. A factor in common has been that the substituted hydroxy group is axial. 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 at or near the glycosidic linkage, and upfield shifts of signals from carbons with their attached protons in -γ-gauche contact.