1‐Picolinyl‐5‐azido Thiosialosides: Versatile Donors for the Stereoselective Construction of Sialyl Linkages

作者：Jian Chen, Thomas Hansen, Qingju Zhang, De‐Yong Liu, Yao Sun, Hao Yan, Jeroen D. C. Codée, Richard R. Schmidt, Jiansong Sun · 发表于：Angewandte Chemie International Edition · 年份：2019 · DOI：10.1002/anie.201909177 · 被引用次数：41 · 研究领域：Carbohydrate Chemistry and Synthesis、Glycosylation and Glycoproteins Research、Chemical Synthesis and Analysis

thiosialyl donor was designed and synthesized, based on which a new sialylation protocol was established. In comparison to conventional sialylation methods, the new protocol exhibited obvious advantages, including excellent α-stereoselectivity in the absence of a solvent effect, broad substrate scope encompassing the challenging sialyl 8- and 9-hydroxy groups of sialic acid acceptors, flexibility in sialoside derivative synthesis, high temperature tolerance and easy scalability. In particular, the applicability to the synthesis of complex and bioactive N-glycan antennae when combined with the MPEP glycosylation protocol via the "latent-active" strategy has been shown. Mechanistically, the excellent α-stereoselectivity of the novel sialylation protocol could be attributed to the dramatic electron-withdrawing effect of the protonated Pic groups, which was supported by control reactions and DFT calculations.