Glycosyl iodides are highly efficient donors under neutral conditions
作者:Michael J. Hadd、Jacquelyn Gervay
DOI:10.1016/s0008-6215(99)00146-9
日期:1999.7
Abstract Glycosyliodides have been prepared and subjected to glycosylation underneutralconditions. The reactions are highly efficient, giving α glycosides even with sterically demanding glycosyl acceptors. Glucosyl iodides react with allyl alcohol slowest and require refluxing conditions. Galactosyl iodides are intermediate in reactivity, providing the allyl glycoside in 3 h at room temperature
A straightforward and scalable method for the synthesis of protected 2-hydroxyglycals is described. The approach is based on the chlorination of carbohydrate-derived hemiacetals, followed by an elimination reaction to establish the glycal moiety. 1,2-dehydrochlorination reactions were studied on a range of glycosyl chlorides to provide suitable reaction conditions for this transformation. Benzyl ether
A privileged Glycon! A radical‐addition Meerwein–Ponndorf–Verley (MPV) reduction sequence provides access to functionalizedα‐CF2‐galactosides (see scheme). Introduction of a CF2Br group in the pseudo‐anomeric position aided the transfer of an aglycon chain from O‐2 to C‐1′ through an intramolecular addition–reduction sequence, which involved a Br–Li exchange. This methodology gives access to a wide
Synthesis and immunological evaluation of fluorinated α-C-galactosylceramide analogs
作者:Sophie Colombel、Nathalie Van Hijfte、Thomas Poisson、Xavier Pannecoucke、Fanny Monneaux、Eric Leclerc
DOI:10.1016/j.jfluchem.2015.02.014
日期:2015.5
A synthesis of difluorinated α-C-galactosylceramides analogs featuring an extra hydroxy group in 1′-position is reported. These compounds were prepared according to unprecedented and unusual methodologies that were previously reported by the authors on simpler substrates. Unfortunately, all four compounds, which feature different lipidic chain lengths, failed to activate iNKT cells. The question whether
Addition of Electrophilic Radicals to 2-Benzyloxyglycals: Synthesis and Functionalization of Fluorinated α-<i>C</i>-Glycosides and Derivatives
作者:Sophie Colombel、Nathalie Van Hijfte、Thomas Poisson、Eric Leclerc、Xavier Pannecoucke
DOI:10.1002/chem.201302070
日期:2013.9.16
A new method for the synthesis of fluorinated α‐C‐glycosides is described. The reactions between highly electrophilicradicals (fluorinated or unfluorinated) and a 2‐benzyloxyglucal or galactal provide 2‐keto‐D‐arabino‐ or 2‐keto‐D‐lyxo‐hexopyranosides through an addition/fragmentation process. Sodium borohydride mediated or Meerwein–Ponndorf–Verley (MPV) reduction of these compounds provides α‐C‐glycosides
描述了一种合成氟化α- C-糖苷的新方法。高亲电子基团(氟化或未氟化)与2-苄氧基葡萄糖或半乳糖之间的反应通过加成/分解过程提供了2-酮基-D-阿拉伯糖基或2-酮基-D-己基-吡喃吡喃糖苷。这些化合物的硼氢化钠介导的或Meerwein-Ponndorf-Verley(MPV)还原可提供具有适当锚定基团的α- C-糖苷,以进行进一步的合成修饰。CF 2 CO 2 i Pr或CF 2的存在假异头位置的Br基团可实现有效的还原/烯化或Br / Li交换/亲核加成序列。这些转变为糖缀合物的氟化C糖苷类似物的合成开辟了道路。