醇(作为糖基受体)与苯基三氟化硅(PhSiF 3)作为催化剂之间的加合物形成允许酸碱催化的糖基化反应,其中O-糖基三氯乙酰胺酸作为糖基供体。这样,可以从各种糖基供体和受体以高异头异构体选择性获得1,2-反式和一些1,2-顺式-糖苷。结果显示,偏爱分子内双分子亲核取代(S N 2型)反应过程,伴有供体和受体激活。
Cooperative Catalysis in Glycosidation Reactions with<i>O</i>-Glycosyl Trichloroacetimidates as Glycosyl Donors
作者:Yiqun Geng、Amit Kumar、Hassan M. Faidallah、Hassan A. Albar、Ibrahim A. Mhkalid、Richard R. Schmidt
DOI:10.1002/anie.201302158
日期:2013.9.16
Thiourea mediates cooperative glycosidation through hydrogen bonding. N,N′‐Diarylthiourea as cocatalyst enforces an SN2‐type acid‐catalyzed glycosidation even at room temperature (see scheme; Bn=benzyl). From O‐(α‐glycosyl) trichloroacetimidates as glycosyldonors and various acceptors, β‐glycosides are preferentially or exclusively obtained.
硫脲通过氢键介导协同糖基化。N,N'-二芳基硫脲作为助催化剂即使在室温下也可增强S N 2型酸催化的糖苷化作用(见方案; Bn =苄基)。从O-(α-糖基)三氯乙酰亚氨酸盐作为糖基供体和各种受体,可以优先或仅从中获得β-糖苷。