据报道,一种精制的四糖的合成涉及到从希玛诺罗海分离出的具有细胞生长抑制作用的三萜皂苷。在相转移条件下,已实现了后期的2,2,6,6-四甲基哌啶基氧基(TEMPO)介导的伯羟基氧化为羧酸的反应。立体选择性糖基化反应是通过使用硫糖苷或糖基三氯乙酰亚胺酸酯活化法进行的,该方法分别与固定在二氧化硅(H 2 SO 4-二氧化硅)上的硫酸与N-碘代琥珀酰亚胺共同使用或单独使用。
据报道,一种精制的四糖的合成涉及到从希玛诺罗海分离出的具有细胞生长抑制作用的三萜皂苷。在相转移条件下,已实现了后期的2,2,6,6-四甲基哌啶基氧基(TEMPO)介导的伯羟基氧化为羧酸的反应。立体选择性糖基化反应是通过使用硫糖苷或糖基三氯乙酰亚胺酸酯活化法进行的,该方法分别与固定在二氧化硅(H 2 SO 4-二氧化硅)上的硫酸与N-碘代琥珀酰亚胺共同使用或单独使用。
Stereocontrolled Synthesis of α-Xylofuranosides Using a Conformationally Restricted Donor
作者:Li Zhang、Ke Shen、Hashem A. Taha、Todd L. Lowary
DOI:10.1021/acs.joc.8b00410
日期:2018.8.3
the use of thioglycoside donors possessing a conformationally restricting xylylene protecting group. The method was shown to provide the desired targets in good to excellent yield and stereoselectivity. Computational investigations support the proposal that the protecting group locks the electrophilic intermediate in these reactions into a conformation that leads to the high selectivity. The power
β-Selective Arabinofuranosylation Using a 2,3-<i>O</i>-Xylylene-Protected Donor
作者:Akihiro Imamura、Todd L. Lowary
DOI:10.1021/ol101520q
日期:2010.8.20
Reported is a novel stereoselective beta-arabinofuranosylation that makes use of a conformationally restricted 2,3-O-zylylene-protected arabinofuranosyl donor. Optimization of the reaction conditions showed that factors including the structure of the acceptor alcohol, substrate concentration, and protecting group on O-5 of the donor affect the stereochemical outcome of the glycosylation. To demonstrate the utility of the methodology, the synthesis of an oligosaccharide fragment from the mycobacterial cell wall polysaccharide lipoarabinomannan was carried out.