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Determination of the Karplus relationships for the C-2, H-1′ and C-6, H-1′ vicinal coupling paths of uridine derivatives

✍ Scribed by David B. Davies; Pramila Rajani; Malcolm MacCoss; Steven S. Danyluk

Publisher
John Wiley and Sons
Year
1985
Tongue
English
Weight
581 KB
Volume
23
Category
Article
ISSN
0749-1581

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✦ Synopsis

A number of uracil cyclo-nucleosides with known glycosidic bond conformations have been synthesized as model compounds for evaluating the Karplus parameters of vicinal carbon-proton coupling across the glycosidic bond. The magnitudes of "J( C-2, H-1') and'J(C-6, H-1') were determined from proton-coupled C NMR measurements, and both coupling constants showed an approximate Karplus dependence with dihedral angle. Carem analysis of the results on model compounds reveals that the C-2, H-1' and C-6, H-1' coupling paths are not equivalent, and so the magnitudes of Karplus parameters have been determined for each coupling path for the Karplus relationship in the form "J= A cosz 0 + B cos 0 + C, i.e. & = 6.2, B6 = -2.4 and C, = 0.1 Hz and Az = 5.0, & = -2.1 and C, = 0.1 Hz. Comparison is made between proton-carbon coupling magnitudes in nucleoside and peptide coupling paths.

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