The base-catalysed anomerization of dinitrophenyl glycosides: evidence for a novel reaction mechanism
作者:Leise A. Berven、David Dolphin、Stephen G. Withers
DOI:10.1139/v90-288
日期:1990.10.1
The mechanism of base-catalysed anomerization of per-O-acetylated 2,4-dinitrophenyl-β-D-glucopyranoside in dimethylsulfoxide has been investigated using a variety of techniques. A mechanism involving proton abstraction at C-1 was eliminated by the absence of proton exchange at that center and the measurement of a secondary deuterium kinetic isotope effect for the 1-deuterio substrate. A mechanism involving
已使用多种技术研究了二甲基亚砜中过氧乙酰化 2,4-二硝基苯基-β-D-吡喃葡萄糖苷的碱催化异构化机制。由于在该中心不存在质子交换以及对 1-氘底物的二次氘动力学同位素效应的测量,消除了涉及 C-1 处质子提取的机制。基于对反应速率的远程取代基影响以及苯基部分与添加的酚盐没有任何交换,使得涉及酚盐脱离和重组的机制不太可能。涉及由二甲基亚磺酰基阴离子的攻击引发的亲核芳族取代生成葡萄糖氧基阴离子中间体的机制与反应性芳基中间体异头化和重组与观察结果一致。观察到紫色的迈森海默复合中间体和观察到的底物之间的交换进一步支持了这种机制……