tetraalkylammonium salts containing xyloside- and xylobioside-based anionic moieties have been prepared. Two stereoselective routes have been developed: i) a chemical pathway in four steps from D-xylose, and ii) a chemoenzymatic pathway directly from biomass-derived xylans. These salts displayed interesting properties as ionic liquids. Their structures have been correlated to their thermal properties (melting
Anomeric alkylations and acylations of unprotected mono- and disaccharides mediated by pyridoneimine in aqueous solutions
作者:Kalyan Dey、Narayanaswamy Jayaraman
DOI:10.1039/d1cc07056h
日期:——
A site-specific deprotonation followed by alkylations and acylations of sugar hemiacetals to the corresponding alkyl glycosides and acylated sugars in aqueoussolutions is disclosed herein. Pyridoneimine as a new base is developed to mediate the deprotonation of readily available sugar hemiacetals and further reactions with alkylation and acylation agents.
Synthesis of bio-based molecules from plant biomass with chemoenzymatic pathways represents a challenging task for the development of green chemistry. In this context, an efficient two-step chemoenzymatic sequence has been achieved for the preparation of triazole-linked xylosides and xylobiosides from biomass-derived xylans. The synthesis of propargyl xyloside and xylobioside catalysed by a xylanase in an aqueous medium was first studied and improved according to different reaction parameters. Cycloaddition reactions between the terminal alkyne moiety of these xylosides or xylobiosides and various aliphatic, aromatic or functionalized azides (âclick chemistryâ) afforded various triazole-linked O-xylosides and O-xylobiosides in high yields. These molecules are of interest for different biological applications.