{sup 13}C-{sup 1}H spin-coupling constants in the {beta}-D-ribofuranosyl ring: Effect of ring conformation on coupling magnitudes
- Univ. of Notre Dame, IN (United States)
Experimental and computational methods have been used to examine the behavior of one-, two-, and three-bond {sup 13}C-{sup 1}H spin-coupling constants ({sup 1}J{sub CH}, {sup 2}J{sub CH} and {sup 3}J{sub CH}, respectively) within the {beta}-D-ribofuranosyl ring 1 that may be potentially affected by ring conformation. Ab initio molecular orbital (MO) calculations at the HF/6-31G{sup *} and MP2/6-31G{sup *} levels of theory were employed to assess the effect of ring conformation on molecular parameters (i.e.,bond lengths, angles, and torsions) of {beta}-D-ribofuranose (2) and methyl {beta}-D-ribofuranoside (3), and these data were validated through comparison to corresponding parameters obtained by X-ray crystallography. The MO-derived structural data were subsequently used to compute {sup 1}J{sub CH}, {sup 2}J{sub CH} and {sup 3}J{sub CH} values in 2 as a function of ring conformation. This predicted behavior was then tested experimentally through the measurement of J{sub CH} values in conformationally-rigid model compounds (aldopyranosides) containing {sup 13}C-{sup 1}H coupling pathways similar to those found in specific conformers of 2 and was examined for consistency with previously-derived empirical rules correlating J{sub CH} with structure in carbohydrates. Available J{sub CH} data obtained on several biologically-important compounds containing {beta}-D-ribofuranosyl rings have been interpreted in light of the new correlations with ring conformation. 52 refs., 12 figs., 6 tabs.
- OSTI ID:
- 226723
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 6 Vol. 118; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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