An unusual glycosylation product from a partially protected fucosyl donor under silver triflate activation conditions
作者:Robin Daly、Eoin M. Scanlan
DOI:10.1039/c3ob42073f
日期:——
Partially protected glycosyl donors are extremely useful reagents for oligosaccharide synthesis allowing more facile deprotection and enhanced activity due to lower steric restraints. A partially protected fucosyl donor containing tert-butyldimethylsilyl (TBDMS) protecting groups was activated under bromine–silver triflate conditions in the presence of primary alcohols and found to give difucoside products exclusively, in good yield with excellent diastereoselectivity. The dimerisation reaction appears to require a conformational relaxation of steric crowding, induced upon activation of the glycosyl donor. The scope and limitations of this unusual glycosylation methodology are reported.
部分保护的糖基供体是合成寡糖的极佳试剂,由于空间位阻较小,脱保护反应更加容易,活性也更高。在溴-银三氟甲磺酸盐条件下,含有叔丁基二甲基硅烷(TBDMS)保护基团的半保护型岩藻糖基供体在伯醇存在下被活化,并发现仅生成二岩藻糖苷产物,且收率较高,具有优异的立体选择性。二聚化反应似乎需要糖基供体活化后引起的构象松弛,以消除空间位阻。本文报告了这种不同寻常的糖基化方法的应用范围和局限性。