摘要用三氟甲磺酸三甲基甲硅烷基酯(NMR)和气相色谱法研究了全甲基化的甲基d-吡喃葡萄糖苷的三元甲硅烷基化反应。初始速率分析表明,在不同的催化剂浓度下,β到α的异化速率要快于相反的速率。底物的总消失速率比相反的端基异构体的出现速率快,这是因为形成了yl型化合物。后者的结构是基于1 H和13 C NMR光谱提出的,尽管它是不可分离的。环状和无环的氧鎓离子似乎都是异构化的中间体。前者似乎是形成吡啶型化合物以及α-糖苷键的异构化的关键中间体。
Anomerization and transglycosylation reactions of permethylated methyl d-glycopyranosides
作者:Chang Kiu Lee、Eun Ju Kim、In-Sook Han Lee
DOI:10.1016/0008-6215(93)84183-7
日期:1993.2
Abstract The anomerization reactions of permethylatedmethyl d -glycopyranosides in the presence of various Lewis acid catalysts, such as Me3SiOTf, Me3SiOMs, BF3·OEt2, or TiCl4 were examined in dichloromethane solution. β Anomers of the glycosides anomerized to the α anomer very rapidly, but the anomerizations in the opposite direction were slower. Transglycosylationreactions of the glycosides in the