Ionic liquid-assisted catalysis for glycosidation of two triterpenoid sapogenins

In order to both investigate the universality of ionic liquid-based catalytic systems for synthesis of triterpene saponins and explore their effective application methods together with the catalytic behaviors of ionic liquids in related reactions by comparison between different initiators, oleanolic acid and ursolic acid were selected to establish a catalytic system for glycosylation in this study as typical representatives of pentacyclic triterpene sapogenins. As a result, it was found that the system of [C4mim][OTf] + TMSOTf in the reactions between the glycosyl receptors and donors showed obvious catalytic effects; also, the system was stable and could be recycled. The functions of IL include solvent, cocatalyst and stabilizer, simultaneously; thus, the current catalytic system is greener, simpler and more efficient. The reaction time was short, and only β-type products were obtained. This study offers a reference for developing a new glucoside synthesis technology and provides sufficient preliminary exploration and basic data for further large-scale applications.