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首页> 外文期刊>Chemistry: A European journal >Neighboring-group participation by C-2 ether functions in glycosylations directed by nitrile solvents
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Neighboring-group participation by C-2 ether functions in glycosylations directed by nitrile solvents

机译：C-2醚功能的邻基参与在腈溶剂指导的糖基化中

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摘要

Ether-protecting functions at C-2 hydroxy groups have been found to play participating roles in glycosylations when the reactions are conducted in nitrile solvent mixtures. The participation mechanism is based on intramolecular interaction between the lone electron pair of the oxygen atom of the C-2 ether function and the nitrile molecule when they are positioned in a cis configuration. A 1,2-cis glycosyl oxazolinium intermediate is formed. This participation, in conjunction with the anomeric effect of the glycosyl donor, confers high 1,2-trans selectivities on glycosylations. Further application of this concept has led to efficient preparations of α-(1→5)-arabinan oligomers.
机译：当在腈溶剂混合物中进行反应时，已发现在C-2羟基上的醚保护功能在糖基化中起参与作用。参与机制基于C-2醚功能的氧原子的孤电子对和腈分子以顺式排列时的分子内相互作用。形成1，2-顺式糖基恶唑啉鎓中间体。这种参与，再加上糖基供体的异头作用，赋予糖基化较高的1，2-反式选择性。该概念的进一步应用导致了α-（1→5）-阿拉伯聚糖低聚物的有效制备。

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