Direct Synthesis of 2,6-Dideoxy-β-glycosides and β-Rhamnosides with a Stereodirecting 2-(Diphenylphosphinoyl)acetyl Group.

作者：Xianglai Liu, Yetong Lin, Wenyi Peng, Zhaolun Zhang, Longwei Gao, Yueer Zhou, Zhe Song, Yingjie Wang, Peng Xu, Biao Yu, Haopeng Sun, Weijia Xie, W. Li · 发表于：Angewandte Chemie · 年份：2022 · 被引用次数：28 · 研究领域：Medicine

Anomeric stereocontrol is usually one of the major issues in the synthesis of complex carbohydrates, particularly those involving β-configured 2,6-dideoxyglycosides and D/L-rhamnoside moieties. Herein, we report that 2-(diphenylphosphinoyl)acetyl is highly effective as a remote stereodirecting group in the direct synthesis of these challenging β-glycosides under mild conditions. A deoxy-trisaccharide as a mimic of the sugar chain of landomycin E was prepared stereospecifically in high yield. The synthetic potential was also highlighted in the synthesis of Citrobacter freundii O-antigens composed of a [→4)-α-D-Man p -(1→3)-β-D-Rha p -(1→4)-β-D-Rha p -(1→] repeating unit, wherein the convergent assembly up to a nonasaccharide was realized with a strongly β-directing trisaccharide donor. Variable-temperature NMR studies indicate the presence of intermolecular H-bonding between the donor and the bulky acceptor as direct spectral evidence in support of the concept of hydrogen-bond-mediated aglycone delivery.