The search for d-glucose derivatives suitable for the study of natural hydrogen isotope fractionation

Abstract

In order to apply Site-specific Natural Isotope Fractionation (SNIF) to chemical, biochemical, and environmental studies of d-glucose, there is a need for readily prepared compounds which give 2H NMR spectra with all or most signals resolved. Changing substituents of C-1 and/or C-6 of α- d-glucopyranose pentaacetate improved the dispersion of deuterium signals, the best results being achieved with 1,2,3,4-tetra- O-acetyl-6-deoxy-6-thiocyanato-α- d-glucopyranose, for which only the 2H-2 and 2H-4 signals were not resolved, and with 2,3,4-tri- O-acetyl-6-bromo-6-deoxy-α- d-glucopyranosyl bromide, for which only the 2H-6a and 2H-6b signals were not resolved. Periodate oxidation of methyl 4,6- O-benzylidene-α- d-glucopyranoside and 4,6-dichloro-4,6-dideoxy- d-galactose was also examined as a possible source of useful compounds. Products obtained from the benzylideneglucoside gave inadequate resolution and broad deuterium signals. The oxidation of 4,6-dichloro-4,6-dideoxy- d-galactose was not straightforward. The α anomer was oxidised more rapidly than the β anomer. The oxidation product, 2,4-dichloro-2,4-dideoxy-3- O-formyl- d-threose, was too labile to be isolated pure and its hydrolysis to 2,4-dichloro-2,4-dideoxy- d-threose was accompanied by a slow elimination to form 2,4-dichlorobut-2-enal.