Spectroscopy and Conformational Features of Carbohydrates

Bochkov, V. M. Dashunin, A. S. Shashkov, and N. K. Kochetkov, Izoest. Akad. Nauk 

Grindley and Szarek have deduced the conformations of the seven-membered ring in 2,5-G-methylene- and l,3 2,5-di-0-methylene-D-mannitoland 1,6-di-0-benzyl-2,5-0-methylene-D- raZ)/ o-hex-3-ulose in solution from the geminal and vicinal proton coupling constants. 

Reviews have appeared on the conformations of mono- and poly-saccharides (in Russian) and the use of n.m.r. spectroscopy for determining the anomeric configuration of monosaccharides and their derivatives.  

Angyal s group has reported a detailed n.m.r. study of the tautomeric equilibria of the 2-hexuloses and some of their derivatives in aqueous solution -all the resonances in the n.m.r. spectra were assigned with the aid of specifically deuteriated compounds. The proportions of the anomeric furanoses and pyranoses present in solutions of the 2-hexuloses at equilibrium in deuterium oxide at 27 °C are shown in the Table (cf. Volume 8, p. 172), and the results were discussed in terms of conformational analysis. 

The use of n.m.r. spectroscopy in an automated procedure for the quantitative or qualitative analysis of mixtures of monosaccharides and cyclitols is referred to in Chapter 2. The technique was applied to the analysis of components extracted from various tissues of Pinus radiata and gave results comparable with those obtained by other analytical techniques. 

Medium effects (corrected for the bulk-susceptibility effect) have been reported for four commonly used solvent-internal reference systems in a paper by Stephen and his co-workers, who point out that the difference in chemical shifts between internal and external reference signals may be as great as 0.54 p.p.m. A novel type of noise-modulated, heteronuclear decoupling has been used by Evelyn and Hall to simplify the n.m.r. spectra of sugar derivatives containing the — CHgF group. By suitable adjustment of the modulation bandwidth and the radio-frequency intensity, the resonances of the coupled nuclei are broadened sufficiently 

spectra of some of the components of the nebramycin complex have been reported. Resonances of the individual nitrogen nuclei were assigned by comparison of the spectra with those of structurally similar compounds. Substituent effects and the effects of pH on the N chemical shifts were also examined. 

A simple modification of a conventional Fourier transform n.m.r. spectrometer has made it feasible to apply selective, radiofrequency pulses at the resonance frequency of one or more proton resonances and to monitor the effects of these perturbations in the usual way. 2, 3 -0-Isopropylideneuridine was used to illustrate how this technique can be used to measure selective spin-4attice relaxation rates, to eliminate unwanted resonances by selective saturation or by selective partial relaxation, and to carry out the pulse equivalent of a INDOR 

Both H and n.m.r. measurements have indicated that a solution of o-hamamelose (2-C-hydroxymethyl-D-ribose) in either deuterium oxide or DMSO contains two furanose and two pyranose ( C ) forms.  

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Carbohydrate Chemistry, Royal Society of Chemistry, vol. 31, 2000 R41 Anonymous (U.K.), NMR Spectroscopy and Conformational Features , p. 312... 

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