Synthesis of β‐Glucosides with 3‐
<i>O</i>
‐Picoloyl‐Protected Glycosyl Donors in the Presence of Excess Triflic Acid: Defining the Scope
作者:Michael P. Mannino、Alexei V. Demchenko
DOI:10.1002/chem.201905278
日期:2020.3.2
Excellent β-stereoselectivity for the glycosylation with glucosyl donors equipped with the 3-O-picoloyl (Pico) group, without the use of participating group, was achieved in the presence of NIS/excess TfOH promoter system. A complete investigation of the scope of this reaction was performed, revealing all important attributes of successful glycosylation. While altering the halogen source was tolerated
在存在NIS /过量TfOH启动子系统的情况下,在不使用参与基团的情况下,对于配备有3-O-picoloyl(Pico)基团的葡萄糖基供体的糖基化具有出色的β-立体选择性。对该反应范围进行了全面研究,揭示了成功糖基化的所有重要属性。在容忍改变卤素源的同时,三氟甲磺酸根阴离子的取代导致立体选择性的完全丧失。经确定,Pico基团的质子化在该反应中至关重要。还发现质子化吡啶环的稳定性或程度是获得高立体选择性的另一个重要关键因素。发现受体的亲核性与所获得的立体选择性成正比,暗示了类似于SN 2的机制。