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Angular dependence of vicinal carbon-proton coupling constants for conformational studies of the hydroxymethyl group in carbohydrates

✍ Scribed by Igor Tvaroška; Jan Gajdoš

Publisher
Elsevier Science
Year
1995
Tongue
English
Weight
624 KB
Volume
271
Category
Article
ISSN
0008-6215

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✦ Synopsis

A theoretical study is presented of the dependence on the hydroxymethyl group conformation of vicinal carbon-proton coupling constant 3Jc, n in a series of 16 hexopyranoses. Calculated 3Jc, H values for both anomers of o-glucopyranose (1), D-mannopyranose (2), D-allopyranose (3), D-altropyranose (4), o-galactopyranose (5), o-talopyranose (6), o-gulopyranose (7), and Didopyranose (8) are based on the FTP formulation in the semi-empirical approximation of INDO. The dependence of the coupling constants on the dihedral angle to c between the coupling carbon atom C-4 and protons H-6 is represented by a trigonometric function of the form3Jc.H = 5.8cos2toc --1.6costoc+0.28sin2to c --0.02sintoc+0.52. It was found that the configuration at the anomeric and C-4 carbon atoms does not show any significant influence on 3Jc, n values. Agreement of calculated and experimental values available for mono-and oligo-saccharides is satisfactory. Based on these results, it is concluded that proposed equation for 3Jc, H values can be used as a tool for estimation of the conformational properties of the hydroxymethyl group in monosaccharides and of (1 ~ 6)-linked oligosaccharides in solution.

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