Neighboring-Group Participation by C-2 Ether Functions in Glycosylations Directed by Nitrile Solvents
作者:Chin-Sheng Chao、Ching-Yu Lin、Shaheen Mulani、Wei-Cheng Hung、Kwok-kong Tony Mong
DOI:10.1002/chem.201100732
日期:2011.10.17
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
当在腈溶剂混合物中进行反应时,已发现在C-2羟基处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。形成一个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)-阿拉伯低聚物的高效制备。