ISSN:
0749-1581
Schlagwort(e):
N-Acetylneuraminic acid
;
Configurational assignment
;
1H and 13C NMR spectra
;
Geminal C,H coupling constants
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
High field 1H and 13C NMR spectra were recorded of N-acetylneuraminic acid, its methyl ester and its per-O-acetylated methyl ester. The sign and the magnitudes of the geminal coupling constants between the H-3 protons and the C-2 quaternary anomeric carbon were determined by heteronuclear 2D-experiments. The C-2,H-3ax coupling in the α anomers (-8 Hz) was significantly more negative than that in the β anomers (-3 to -4 Hz). Therefore, the determination of 2J(C-2,H-3ax) offers a unique criterion for anomeric assignment in sialic acid ketosides. The geminal coupling constants are discussed in terms of the number and orientation of the oxygen substituents. Due to their 3-deoxy function adjacent to the quaternary anomeric centre, sialic acids give novel contributions to the correlation of carbon-proton coupling constants with molecular geometries in carbohydrates.
Zusätzliches Material:
9 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/mrc.1260281011
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