DEUTERIUM-INDUCED DIFFERENTIAL ISOTOPE SHIFT C-13 NMR .1. RESONANCE RE-ASSIGNMENTS OF MONOSACCHARIDES AND DISACCHARIDES

Previous assignments of natural-abundance 13CNMR chemical shifts of mono-and disaccharides have been reevaluated by use of a newly developed differential isotope shift (DIS) technique. Deuterium-induced 13C isotope shifts were produced through rapid interchange of carbohydrate hydroxyl groups in a D2O environment. The differential shift positions (D2O vs. H2O environments) were measured simultaneously in the magnetic field with a dual coaxial NMR cell. Each isotopic chemical shift position was sharply defined because of rapid OH and OD interchange in the separate, respective solvent environments. The largest induced upfield displacements due to deuterium substitution of OH were noted for those carbons bearing hvdroxyl groups, β shifts (0.14 ppm). (β shifts at C-l were smaller (0.11 ppm) than all other β induced shifts. Shifts due to vicinal OD, γ shifts, were ~0.03-0.06 ppm and additive. Differences in induced 7 shifts directed from cis vs. trans hydroxy! groups at C-l were found to be statistically significant. Isotope shift parameters were calculated from a linear regression analysis of data compiled from 12 structurally different pyranose structures. These parameters were used to calculate the isotope shifts for other pyranose and furanose mono-and disaccharides. DIS analysis was also applied to different substituted carbohydrates in both aqueous and nonaqueous systems as well as α- and β-D-glucuronopyranoses. © 1979, American Chemical Society. All rights reserved.