Due to the wide presence of carbohydrates in nature and their crucial roles in numerous important biological processes, oligosaccharides have attracted a lot of attention in synthetic organic chemistry community. Many innovative synthetic methods have been developed for oligosaccharide synthesis, among which the pre-activation based glycosylation is particularly noteworthy. Traditionally, glycosylation reactions are carried out when the glycosyl donor and the acceptor are both present when the promoter is added. In comparison, the pre-activation based glycosylation is unique, where the glycosyl donor is activated by the promoter in the absence of the acceptor. Upon complete donor activation, the acceptor is added to the reaction mixture enabling glycosylation. The key step in any oligosaccharide synthesis is the stereoselective formation of the glycosidic bond. As donor activation and acceptor glycosylation are temporally separated, pre-activation based glycosylation can bestow unique stereochemical control. This review systematically discusses factors impacting the stereochemical outcome of a pre-activation based glycosylation reaction including substituents on the glycosyl donor, reaction solvent, and additives. Applications of pre-activation based stereoselective glycosylation in assembly of complex oligosaccharides are also discussed.

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基于预激活的立体选择性糖基化

由于碳水化合物在自然界中的广泛存在及其在众多重要生物过程中的关键作用，低聚糖在合成有机化学界引起了广泛关注。已经开发了许多创新的合成方法用于寡糖合成，其中基于预活化的糖基化尤其值得注意。传统上，当添加启动子时糖基供体和受体都存在时，会进行糖基化反应。相比之下，基于预激活的糖基化是独一无二的，其中糖基供体在没有受体的情况下被启动子激活。供体完全活化后，受体被添加到反应混合物中，从而实现糖基化。任何寡糖合成的关键步骤是糖苷键的立体选择性形成。由于供体激活和受体糖基化在时间上是分开的，基于预激活的糖基化可以赋予独特的立体化学控制。本综述系统地讨论了影响基于预活化的糖基化反应立体化学结果的因素，包括糖基供体上的取代基、反应溶剂和添加剂。还讨论了基于预激活的立体选择性糖基化在复杂寡糖组装中的应用。本综述系统地讨论了影响基于预活化的糖基化反应立体化学结果的因素，包括糖基供体上的取代基、反应溶剂和添加剂。还讨论了基于预激活的立体选择性糖基化在复杂寡糖组装中的应用。本综述系统地讨论了影响基于预活化的糖基化反应立体化学结果的因素，包括糖基供体上的取代基、反应溶剂和添加剂。还讨论了基于预激活的立体选择性糖基化在复杂寡糖组装中的应用。