A B-11 AND C-13 NMR DETERMINATION OF THE STRUCTURES OF BORATE COMPLEXES OF PENTOSES AND RELATED SUGARS
A B-11 AND C-13 NMR DETERMINATION OF THE STRUCTURES OF BORATE COMPLEXES OF PENTOSES AND RELATED SUGARS
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DOI：
10.1016/s0040-4020(01)86149-4
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发表时间：
1988-01-01
期刊：
影响因子：
2.1
通讯作者：
VERCHERE, JF
中科院分区：
文献类型：
--
作者：
CHAPELLE, S;VERCHERE, JF
一项11B核磁共振研究表明，这四种戊糖和己糖一样，在水溶液中同时形成1:1和1:2硼酸盐络合物，与先前的报道相反。它还表明，在这两个物种中，硼酸盐离子与邻近的二醇位点结合。用电位法测定了相应的稳定性常数。大多数1:2配合物的结构通过13C核磁共振光谱得到了精确的结构，因为携带螯合二醇基团的碳原子被明显地去屏蔽，并增加了1JCH值。通过将糖按一系列相关的结构分组，结果变得合理。所有的糖都以呋喃糖的形式络合。阿拉伯糖-半乳糖-果糖系列和木糖-山梨糖系列得到的配合物类型相同，包括头端羟基和最近的CHOH环。非常稳定的1:2的d -核糖络合物被证明是两种物质以恒定比例的混合物，硼酸盐被结合在C-1， C-2或C-2， C-3上。同样具有两个顺式CHOH基团的lyxo-tagato系列糖也得到了相同的结果。
A 11B NMR study demonstrated that the four pentoses, like hexoses, form concurrently 1:1 and 1:2 borate complexes in aqueous solution, contrary to earlier reports. It also showed that in both species, the borate ion was bound to a vicinal diol site. The corresponding stability constants were determined by a potentiometric method. The structures of most 1:2 complexes were precised by 13C NMR spectroscopy, since the carbon atoms which bear the chelating diol group were clearly deshielded and had increased 1JCH values. The results were rationalised by grouping the sugars in series of related configurations. All sugars were complexed in furanose form. Those of the arabino-galacto-fructo series and of the xylo-gluco-sorbo series gave the same type of complex involving the anomeric hydroxyl group and the nearest ring CHOH. The very stable 1:2 complex of D-ribose was shown to be a mixture of two species in constant ratio, borate being bound either at C-1, C-2 or at C-2, C-3. The same result was obtained with the sugars of the lyxo-tagato series, which also possessed two cis CHOH groups.