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首页> 外文期刊>Bulletin of the Chemical Society of Japan >Selective 3-O-and/or 6-O-glycosidation of unprotected O-and S-Glycosides promoted by an intramolecularly coordianted arylboronic compound
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Selective 3-O-and/or 6-O-glycosidation of unprotected O-and S-Glycosides promoted by an intramolecularly coordianted arylboronic compound

机译：分子内配位芳基硼化合物促进的未保护的O-和S-糖苷的选择性3-O-和/或6-O-糖基化

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摘要

Arylboronic compound 1 that has intramolecular coordination promotes highly regioselective 3-O-and/or 6-O-glucosidation and -galactosidation of methyl fucopyanoside,methyl galactopyranoside,methyl mannopyranoside,rho-methylphenyl 1-thiogalactopyranoside,and rho-methylphenyl 1-thiomannopyranoside with peracetylated glucopyranosyl bromide or galactopyranosyl bromide as a glycosyl donor in the presence of Ag_2CO_3,Et_4NI,and molecualr sieves 4A in THF.Glycosylacceptors and promoter 1 form cyclic boronates at cis-vicinaldiol (3,4-diol or 2,3-diol) and/or 4,6-diol moieties with concomitant activation of the less hindered 3-O (equatorial) and/or 6-O(primary)nucleophiles via intramolecular O->B coordiantion.This reaction provides a novel method of simultaneous one-pot 3,6-O-double glycosidation(glucosidation and galactosidation) to give trisaccharides.however,attempted mannosidation with peracetylated mannopyranoxyl bromide only gives rise to orthoesters.
机译：具有分子内配位作用的芳基硼化合物1促进甲基岩藻糖苷，甲基吡喃半乳糖苷，甲基甘露吡喃糖苷，rho-甲基苯基1-硫代吡喃半乳糖苷和rho-甲基苯基1-硫代吡喃葡糖苷的高度区域选择性的3-O-和/或6-O-葡萄糖苷化和-半乳糖苷化在Ag_2CO_3，Et_4NI和分子筛4A在THF中存在的情况下，过乙酰化的吡喃葡萄糖基溴化物或吡喃半乳糖基溴化物作为糖基供体。糖基内酯和助催化剂1在顺式-邻位二醇（3,4-二醇或2,3-二醇）和/或4,6-二醇部分，并通过分子内O-> B配位作用同时激活受阻较少的3-O（赤道）和/或6-O（伯）亲核试剂。该反应提供了一种同时进行一锅法的新方法3,6-O-双糖苷化（葡萄糖苷化和半乳糖苷化）产生三糖。但是，过乙酰化的甘露吡喃并溴化甘露糖苷尝试仅生成原酸酯。

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