(1-13C)alditols: elimination of magnetic equivalence in 1H- and 13C-n.m.r. spectra of symmetric compounds through (13C)-substitution.
(1-13C)Glycerol, D-(1-13C)arabinitol, D-(1-13C)ribitol, D-(1-13C)xylitol, D-(1-13C)glucitol, D-(1-13C)mannitol, and D-(1-13C)talitol have been prepared by NaBH4 reduction of the corresponding (1-13C)aldoses. A comparison of the 1H- (300 and 620 MHz) and 13C (75 MHz) n.m.r. spectra of natural and (1-13C)-substituted dissymmetric alditols has permitted the unequivocal assignments of their hydroxymethyl proton and carbon signals and the measurement of several 13C-1H and 13C-13C spin-coupling constants. Similar spectra of (1-13C)-substituted symmetric alditols, however, are more difficult to interpret since they are composed of overlapping 13C-coupled and 13C-noncoupled subspectra. In some cases, 1H difference spectra and 1H-coupled 13C spectra may be used to extract the 13C-1H and 13C-13C spin couplings from the 13C-coupled component. These couplings have been examined in light of conformational models previously proposed, permitting a preliminary evaluation of standard 3JCH and 3JCC values for specific coupling pathways in these compounds.
Garrett
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Department of Chemistry and Biochemistry, University of Notre Dame, IN 46556.
Serianni
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D002236:Carbohydrate Conformation; D002247:Carbon Isotopes; D005990:Glycerol / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008280:Magnetics; D015394:Molecular Structure; D011522:Protons; D012255:Ribitol / Q000737:chemistry; D013402:Sugar Alcohols / Q000737:chemistry*; D014993:Xylitol / Q000737:chemistry
D002247:Carbon Isotopes; D011522:Protons; D013402:Sugar Alcohols; D012255:Ribitol; D005990:Glycerol; D014993:Xylitol