Xu Huanfang, Chen Long, Zhang Qi, Feng Yingle, Zu Yujia, Chai Yonghai
Key Laboratory of Applied Surface and Colloid Chemistry, Shaanxi Normal University, 620 West Chang'an Avenue, Xi'an, Shaanxi, 710119, China.
Chem Asian J. 2019 May 2;14(9):1424-1428. doi: 10.1002/asia.201801740. Epub 2019 Mar 13.
Stereoselective β-mannosylation has been recognized as one of the greatest challenges of carbohydrate chemistry. Herein, we described a practical method for stereoselective construction of β-mannosides by using a 2,6-lactone-bridged thiomannosyl donor through the remote acyl-group participation as well as the steric effect of O-4 substituent. The two effects are enabled through the conversion of a regular mannopyranosyl C conformation into a 2,6-lactone bridged conformation. The lactone donor could be readily prepared in three steps on a gram scale and the β-mannosylation proceeded smoothly with high stereoselectivity for primary, secondary and tertiary alcohol acceptors. In addition, this strategy was successfully applied to the synthesis of a naturally occurring trisaccharide.
立体选择性β-甘露糖基化反应已被公认为碳水化合物化学领域最具挑战性的课题之一。在此，我们描述了一种实用的方法，通过使用2,6-内酯桥连的硫代甘露糖基供体，利用远程酰基参与以及O-4取代基的空间效应，立体选择性地构建β-甘露糖苷。这两种效应是通过将常规甘露吡喃糖基的C构象转化为2,6-内酯桥连构象来实现的。内酯供体可以通过三步反应轻松地以克级规模制备，并且β-甘露糖基化反应能够顺利进行，对伯醇、仲醇和叔醇受体均具有高立体选择性。此外，该策略已成功应用于天然三糖的合成。
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