Complete assignments of the 1H and 13C chemical shifts and JH,H coupling constants in NMR spectra of D-glucopyranose and all D-glucopyranosyl-D-glucopyranosides

Complete assignment of the H-1 and C-13 NMR spectra of all possible D-glucopyranosyl-D-glucopyranosides was performed and the H-1 chemical shifts and proton-proton coupling constants were refined by computational spectral analyses (using PERCH NMR software) until full agreement between the calculated and experimental spectra was achieved. To support the experimental results, the H-1 and C-13 chemical shifts and the spin-spin coupling constants between the non-hydroxyl protons of alpha- and P-D-glucopyranose (1a and 1b) were calculated with density functional theory (DFT) methods at the B3LYP/pcJ-2//B3LYP/ 6-31G(d,p) level of theory. The effects of different glycosidic linkage types and positions on the glucose ring conformations and on the alpha/beta-ratio of the reducing end hydroxyl groups were investigated. Conformational analyses were also performed for anomerically pure forms of methyl D-glucopyranosides (13a and 13b) and fully protected derivatives such as 1,2,3,4,6-penta-O-acetyl-Dglucopyranoses (14a and 14b). (c) 2007 Elsevier Ltd. All rights reserved.