13C-13C spin-spin coupling constants in structural studies:: XXXV.: Stereochemical study of the furanose ring

Theoretical conformational analysis and calculation of C-13-C-13 spin-spin coupling constants of aldofuranoses of the D-series were performed in terms of the self-consistent finite perturbation theory in the INDO approximation. All the examined furanoses were found to prefer an envelope conformation. The main factor responsible for the stereo specificity of the (1)J(1,2) coupling constant is mutual orientation of the hydroxy groups on C-1 and C-2: s-trans isomers are characterized by greater (1)J(1,2) values (by 2-4 Hz) than the corresponding s-cis isomers.