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Conformational dependence of the one-bond carbon–proton coupling constants in oligosaccharides

✍ Scribed by Miloš Hricovíni; Igor Tvaroška

Publisher
John Wiley and Sons
Year
1990
Tongue
English
Weight
411 KB
Volume
28
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

A study is presented of the dependence on conformation of one‐bond carbon‐proton coupling constants in three 1‐4‐linked disaccharides. Calculated ^1^J(CH) values are based on the FPT formulation in the semi‐empirical INDO MO method. The configuration at the anomeric carbon influences the ^1^J(CH) value, and the ^1^J(C‐1′, H‐1′) values are 20–30 Hz higher than the ^1^J(C‐4, H‐4) values. The conformational dependence of ^1^J(CH) on the dihedral angle about the CO bonds is satisfactorily expressed in the analytical form ^1^J(CH) = A cos 2ϕ + B cos ϕ. The constants A‐E are different for the α‐ and β‐anomers. Calculated average values 〈^1^J(C‐1′, H‐1′)〉 = 163.7 Hz and 〈^1^J(C‐4, H‐4)〉 = 146 Hz for methyl β‐xylobioside using PCILO‐calculated abundances of conformers agree well with the experimental values of 162.7 and 147.5 Hz, respectively.

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