A novel promoter, heteropoly acid, mediated chemo- and stereoselective sulfoxide glycosidation reactions
摘要:
The chemo- and stereoselective glycosidations of sulfinylglycosides and alcohols using a heteropoly acid, H3PW12O40, as a new promoter have been developed. (C) 2000 Elsevier Science Ltd. All rights reserved.
to covalently bind Lewis basic fluoride ions in a relatively stable fluorosulfite anion (FSO2−). Herein we report the application of liquid SO2 as a promoting solvent for glycosylation with glycosyl fluorides without any external additive. By using various temperature regimes, the method is applied for both armed and disarmed glucose and mannose-derived glycosyl fluorides in moderate to excellent yields
液态SO 2是一种极性溶剂,可溶解共价和离子化合物。二氧化硫也具有路易斯酸性质,包括在一个相对稳定的fluorosulfite阴离子的能力共价结合路易斯碱性氟化物离子(FSO 2 - )。在本文中,我们报道了液态SO 2作为促进剂用于糖基氟化物的糖基化而没有任何外部添加剂的应用。通过使用各种温度方案,该方法可用于中等和极高产率的武装和解除武装的葡萄糖和甘露糖衍生的糖基氟化物。一系列新戊酰基保护的O-和S-甘露糖苷,以及C的一个实例合成甘露糖苷以证明糖基受体的范围。通过19 F NMR光谱证实了在液体SO 2中与糖基氟糖基化的过程中,亚硫酸氢盐物质的形成。提出了通过溶剂分离的离子对进行的二氧化硫辅助的糖基化机制,而观察到的α,β-选择性是受底物控制的,并且取决于热力学平衡。
Strained olefin enables triflic anhydride mediated direct dehydrative glycosylation
Tf2O mediated dehydrative glycosylation was enabled by strained olefins, including beta-(−)-pinene, and inhibited by other typical bases.
Tf2O介导的脱水糖基化反应是由受限烯烃实现的,包括β-(−)-蒎烯,并受到其他典型碱的抑制。
Direct Dehydrative Glycosylation Catalyzed by Diphenylammonium Triflate
作者:Mei-Yuan Hsu、Sarah Lam、Chia-Hui Wu、Mei-Huei Lin、Su-Ching Lin、Cheng-Chung Wang
DOI:10.3390/molecules25051103
日期:——
dehydrative glycosylations of carbohydrate hemiacetals catalyzed by diphenylammonium triflate under microwave irradiation are described. Both armed and disarmed glycosyl-C1-hemiacetal donors were efficiently glycosylated in moderate to excellent yields without the need for any drying agents and stoichiometric additives. This method has been successfully applied to a solid-phase glycosylation.
A versatile glycosylation strategy via Au(<scp>iii</scp>) catalyzed activation of thioglycoside donors
作者:Amol M. Vibhute、Arun Dhaka、Vignesh Athiyarath、Kana M. Sureshan
DOI:10.1039/c6sc00633g
日期:——
Among various methods of chemical glycosylations, glycosylation by activation of thioglycoside donors using a thiophilic promoter is an important strategy. Many promoters have been developed for the activation of thioglycosides. However, incompatibility with substrates having alkenes and the requirement of a stoichiometric amount of promoters, co-promoters and extreme temperatures are some of the limitations