Solvent dependence of the rotamer population around the interglycosidic C(5)C(6) bond of (1→6)‐β‐linked digalactopyranosides

Abstract

Abstract A 300‐MHz 1 H NMR study of the rotamer population around the interglycosidic C(5)C(6) bond of methyl 2,3, 4 ‐tri‐ O ‐methyl‐6‐ O ‐(2,3,4,6‐tetra‐O‐acetyl‐β‐ D ‐galactopyranosyl)‐β‐ ( 1 ) and ‐α‐ D ‐galactopyranoside ( 2 ) is reported. The existence of the (1→6)‐β‐linkage in these compounds is established by homo‐ and heteronuclear 2‐D NMR techniques. It is shown that the dependence on solvent polarity of the population around the C(5)C(6) bond for the dissaccharides is almost identical to that for monosaccharides. The influences of stereoelectronic effects and solute–solvent interactions on the conformational properties of the interglycosidic linkage are discussed briefly.