A series of glycosyl hemiacetal derivatives have been transformed into thioglycosides and glycosyl thiols in a one-pot two-step reaction sequence mediated by Appel reagent (carbon tetrabromide and triphenylphosphine). 1,2-trans-Thioglycosides and β-glycosyl thiol derivatives were stereoselectively formed by the reaction of the in situ generated glycosyl bromides with thiols and sodium carbonotrithioate. The reaction conditions are reasonably simple and yields were very good.
visible-light-induced palladium-catalyzedHeckreaction for bromine sugars and aryl olefins with high regio- and stereochemistry selectivity for the preparation of C-glycosyl styrene is described. This reaction takes place in one step at room temperature by using a simple and readily available starting material. This protocol can be scaled up to a wide range of glycosyl bromide donors and aryl olefin substrates
Cyanide-Free Synthesis of Glycosyl Carboxylic Acids and Application for the Synthesis of Scleropentaside A
作者:Liang-Jing Zou、Qiang Pan、Cai-Yi Li、Ze-Ting Zhang、Xiao-Wei Zhang、Xiang-Guo Hu
DOI:10.1021/acs.orglett.0c02949
日期:2020.11.6
We have developed a cyanide-free strategy for the synthesis of glycosyl carboxylic acids, which can provide 1,2-trans or 1,2-cis glycosyl carboxylic acids and is compatible with common protecting groups. The synthetic utility was demonstrated by the synthesis of 12 unreported glycosyl acids and the total synthesis of scleropentaside A.
我们开发了一种用于合成糖基羧酸的无氰化物策略,它可以提供 1,2-反式或 1,2-顺式糖基羧酸,并且与常见的保护基团兼容。合成效用通过 12 种未报告的糖基酸的合成和 sclerpentaside A 的全合成得到证明。
Glycosyl-Radical-Based Synthesis of <i>C</i>-Alkyl Glycosides via Photomediated Defluorinative <i>gem</i>-Difluoroallylation
作者:Cai-Yi Li、Yue Ma、Zhi-Wei Lei、Xiang-Guo Hu
DOI:10.1021/acs.orglett.1c03390
日期:2021.11.19
We have developed a stereoselective, glycosyl radical-based method for the synthesis of C-alkyl glycosides via a photomediated defluorinative gem-difluoroallylation reaction. We demonstrate for the first time that glycosyl radicals, generated from glycosylbromides, can readily participate in a photomediated radical polar crossover process, affording a diverse array of gem-difluoroalkene containing
Total synthesis of phenylpropanoid glycoside osmanthuside-B<sub>6</sub> facilitated by double isomerisation of glucose–rhamnose orthoesters
作者:Duc Thinh Khong、Zaher M. A. Judeh
DOI:10.1039/c7ob00198c
日期:——
A convenientsynthesis of phenylpropanoid glycoside osmanthuside-B6 is disclosed. The key steps involved regioselective coumaroylation and rhamnosylation of unprotected phenylethyl-β-D-glucopyranoside to give 2- and 3-O-rhamnosyl orthoester glucopyranosides. Rearrangement of these orthoesters followed by selective removal of their acetyl and allyl groups gave osmanthuside-B6 in 22% overall yield. The