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Equilibres conformationnels de glucides au niveau de liaisons σ sp2-sp3 C-C. III Dérivés d'oximes d'aldéhydo-sucres utilisation de tris-dipivaloylméthanato-europium

✍ Scribed by J. M. J. Tronchet; F. Barbalat-Rey; N. Le-Hong


Publisher
John Wiley and Sons
Year
1971
Tongue
German
Weight
769 KB
Volume
54
Category
Article
ISSN
0018-019X

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✦ Synopsis


Abstract

A series of sugar oximes and O‐methyloximes of the general formula RCHNOR′ (R′  H, CH~3~) have been studied by PMR. spectroscopy. These compounds exist in solution as a mixture of the syn and anti isomers. The conformational equilibrium of the syn isomers seems to consist exclusively of the eclipsed rotamers, whereas for the anti isomers there appears to be a significant contribution from bisecting rotamers. Using tris‐dipivaloylmethanato‐europium it is found that the α proton of the anti oximes is much more deshielded than the corresponding proton of the syn isomers, which means that the downfield shift of a particular proton does not depend exclusively on its distance from the oxygen of the oxyimino group.


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