Various Glycosyl Donors with a Ketone or Oxime Function next to the Anomeric Centre: Facile Preparation and Evaluation of their Selectivities in Glycosidations
作者:Frieder W. Lichtenthaler、Ulrich Kläres、Matthias Lergenmüller、Sabine Schwidetzky
DOI:10.1055/s-1992-34167
日期:——
An efficient one-pot procedure is described for the conversion of a variety of hydroxyglycal esters to their 2-oxoglycosyl bromides which simply comprises of brief treatment with N-bromosuccinimide/methanol at ambient temperature. Exhibiting comparably low anomeric reactivity in glycosidation reactions, these ulosyl bromides, as well as their 2-benzoyloxyimino analogs, can readily be transformed into a range of more reactive glycosyl donors with iodine, pentenyloxy, ethylthio and dithiocarbamoyl residues at the anomeric centre, such that any ß-selective glycosidation may be successfullv achieved.
A convenient and efficient method for the synthesis of 2-hydroxy glycals
作者:Bin Qian、Qi-Dong You
DOI:10.1016/j.tetlet.2012.05.016
日期:2012.7
A convenient and efficientmethod for preparing 2-hydroxy glycals was developed from thioglycosides by using 1,4-dioxane–bromine complex/DMAP as an efficient promoter with good yield (61–85%). In this synthetic method, a wide range of sugar thioglycosides could be used as substrates.
Biomimetic Synthesis of a Leaf-opening Factor, Potassium Isolespedezate, by Direct Formation of Enol-glycoside
作者:Takanori Sugimoto、Minoru Ueda
DOI:10.1246/cl.2004.976
日期:2004.8
However, 1 was synthesized via an indirect route because of the difficulty of directformation of the enol-glycosidic linkage. More efficiency is desired for the preparation of 1 and 2 which are necessary for the synthesis of probe compounds. In this paper, we report the biomimetic synthesis of 1 containing directformation of an enol-glucosidic linkage. This efficient route makes it possible to prepare
AbstractMetabolically stable C‐glycosides are an essential family of compounds in bioactive natural products, therapeutic agents, and biological probes. For their application, development of synthetic methods by connecting glycosides and aglycons with strict stereocontrol at the anomeric carbon, as well as with high functional‐group compatibility and environmental compatibility is a pivotal issue. Although Suzuki–Miyaura‐type C(sp3)−C(sp2) cross‐coupling using glycosyl boronates is a potential candidate for the construction of C‐glycosides, neither the cross‐coupling itself nor the facile synthesis of the coupling precursor, glycosyl boronates, have been achieved to date. Herein, it was succeeded to develop a copper‐catalyzed stereoselective one‐step borylation of glycosyl bromides to glycosyl boronates and palladium‐catalyzed stereospecific cross‐coupling of β‐glycosyl borates with aryl bromides to give aryl β‐C‐glycosides, in which the β‐configuration of the anomeric carbon of the glycosyl trifluoroborates is stereoretentively transferred to that of the resulting aryl C‐glycosides.