CALCULATION OF NMR CHEMICAL-SHIFTS AND SPIN-SPIN COUPLING-CONSTANTS IN THE MONOSACCHARIDE METHYL-BETA-D-XYLOPYRANOSIDE USING A DENSITY-FUNCTIONAL THEORY APPROACH

Density functional theory based approaches were used to calculate chem ical shieldings and spin-spin coupling constants in a monosaccharide, methyl-beta-D-xylopyranoside. Excellent agreement was found between th e computed and experimental data for this monosaccharide both in solut ion and in solid state. The effect of torsion around the C1-O1 bond sh owed that chemical shifts of the anomeric proton, both ring and OI oxy gens as well as C1, C2, and the methyl carbons, strongly depend on the dihedral angle. Similarly, both one-bond and three-bond proton-carbon coupling constants among anomeric proton and anomeric and methyl carb ons[(C(1)JC1-H1) and ((3)JC(Me)-H1), respectively] showed a dependence on the torsion angle Phi.