Lewis Acid Induced Anomerization of Se-Glycosides. Application to Synthesis of α-Se-GalCer

The TiCl4 induced anomerization of selenium glycosides of galacturonic acid derivatives is reported. The reaction was successful for galacturonic acid when various alkyl, alkenyl, alkynyl, saccharide, steroid, and lipid groups were attached to the anomeric Se atom. An increased amount of TiCl4 and/or higher temperature were needed to ensure completion of the reaction in some cases. Yields were higher for reactions carried out at higher dilution. The reaction was applied to the synthesis of Se-based mimics of the potent immunostimulant alpha-GalCer (KRN7000). The research was supported by the Irish Research Council (PhD Scholarship to A.McD.) and NUI Galway (College of Science PhD scholarship to A.McD.). This publication has also emanated in part from research supported by Science Foundation Ireland (SFI, Grant Number 12/IA/1398) and is cofunded under the European Regional Development Fund under Grant Number 14/SP/2710. peer-reviewed 2017-01-22