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。
Silicon Fluorides for Acid-Base Catalysis in Glycosidations
作者:Amit Kumar、Yiqun Geng、Richard R. Schmidt
DOI:10.1002/adsc.201100933
日期:2012.5.21
Adduct formation between alcohols as glycosyl acceptors and phenylsilicon trifluoride (PhSiF3) as catalyst permits acid‐base‐atalyzed glycosidations with O‐glycosyl trichloroacetimidates as glycosyl donors. In this way, from various glycosyl donors and acceptors 1,2‐trans‐ and some 1,2‐cis‐glycosides could be obtained with high anomeric selectivity. A preference for an intramolecular bimolecular nucleophilic
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。