Two-bond C-13-H-1 NMR spin-spin coupling constants ((2)J(CCH)) between C2 and HI of alclopyranosyl rings depend not only on the relative orientation of electronegative substituents on the C1-C2 fragment but also on the C-O torsions involving the same carbons. The latter dependencies were elucidated theoretically using density functional theory and appropriate model pyranosyl rings representing the four relative configurations at C1 and C2, and a 2-deoxy derivative, to probe the relationship between (2)J(C2.H1) magnitude and sign and the C1-O1 (phi, phi) and C2-O2 (alpha) torsion angles. Related calculations were also conducted for the reverse coupling pathway, (2)J(C1.H2). Computed J-couplings were validated by comparison to experimentally measured couplings. (2)J(CCH) displays a primary dependence on the C-O torsion involving the carbon bearing the coupled proton and a secondary dependence on the C-O torsion involving the coupled carbon. These dependencies appear to be caused mainly by the effects of oxygen lone pairs on the C-H and C-C bond lengths along the C-C-H coupling pathway. New parameterized equations are proposed to interpret (2)J(C1.H2) and (2)J(C2.H1) in alclopyranosyl rings. The equation for (2)J(C2.H1) has particular value as a potential NMR structure constraint for the C1-O1 torsion angle (0) comprising the glycosidic linkages of oligosaccharicles.