13C-13C Spin-Spin Coupling Constants in Structural Studies: XXXVII. Rotational Conformations of Hydroxy Groups in Pyranose, Furanose, and Septanose Rings

Rotational surfaces for 13C-13C coupling constants with respect to two dihedral angles at C1 and C2 in model structures of aldopyranoses, aldofuranoses, and aldoseptanoses of the D-series were calculated in terms of the self-consistent finite perturbation theory. Internal rotation of the hydroxy groups exerts an appreciable effect (within 2.5 Hz) on the 13C-13C coupling constants of all cyclic forms of monosaccharides, which provides the possibility for performing conformational analysis of carbohydrates and their metabolites containing pyranose, furanose, and septanose fragments.