Comparative H-1 NMR study of hydroxy protons in galabioside and its S-linked 4-thiodisaccharide analogue in aqueous solution

The NMR data obtained from hydroxy protons have been used to investigate th e presence and absence of intramolecular hydrogen bonding in aqueous soluti ons of 2-(trimethylsilyl)ethyl galabioside (alpha-D-Galp-(1 --> 4)-beta-D-G alp-O(CH2)(2)SiMe3) and the S-linked 4-thiodisaccharide analogue. The data show that there is a weak hydrogen bond interaction between O-6H and O-2'H in galabioside, but not in the thio-analogue. The results are in good agree ment with those reported for the substances in a Me2SO-d(6)solution. It is also shown that the existence of a hydrogen bond can be quite easily monito red by comparing the NMR data of the hydroxy protons. (C) 1999 Elsevier Sci ence Ltd. All rights reserved.