| Abstract
| - Density functional theory (DFT) calculations show thatinternal electronegative substituents perturb 3JCOCC Karpluscurves by phase shifting them with respect to analogouspathways devoid of this substitution. Thus, the J-couplingmaximum, which normally is observed near 180°, is shiftedby ∼15°. These findings suggest that the two types of inter-residue C−O−C−C coupling pathways observed in manyoligosaccharides cannot be treated using a generalized 3JCOCCKarplus equation. Quantitative interpretations of trans-glycoside J-couplings to evaluate linkage conformations willneed to take this effect into account.
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