Stereoselective Synthesis of a Tetrasaccharide Fragment from Rhamnogalacturonan
<scp>II</scp>
Side Chain A
作者:Jin‐Cai Lei、Yuan‐Yuan Jiang、Yi‐Fei Xia、Qing Fang、Shi‐Chao Duan、Yu‐Xiong Ruan、Jin‐Song Yang
DOI:10.1002/cjoc.202200177
日期:2022.8
An efficient synthesis of a complex tetrasaccharide fragment 1 structurally related to rhamnogalacturonan II side chain A has been accomplished through a stepwise glycosylation strategy. Challenges involved in the synthesis include the facile construction of the sterically crowded l-fucopyranose core and the stereoselective formation of two 1,2-cis-glycosidic linkages. The 3,4-disubstituted l-fucopyranoside
已通过逐步糖基化策略实现了与鼠李糖半乳糖醛酸 II 侧链 A 结构相关的复杂四糖片段1的有效合成。合成中涉及的挑战包括空间拥挤的l- fucopyranose 核心的简单构建和两个 1,2- cis-糖苷键的立体选择性形成。通过“逆时针”糖基化序列成功构建了3,4-二取代的L-岩藻糖苷结构,即中心岩藻糖单元的反应性较低的轴向4-OH基团首先被糖基化,然后是3-OH。此外,还开发了一种 2-吡啶羰基辅助的 α- d-木糖基化合成 α - d-xylopyranosidic 键和 3,4- O-苯甲酰基控制的 α- l-半乳糖基化反应用于立体选择性合成相应的 α - l -galactopyranosidic键。