Metal-free and VOC-free Synthesis of O-Glycosides in Supercritical CO2

Identifier:  PC:3121

Handle: https://hdl.handle.net/20.500.11797/PC3121

Authors:  Castillón, S.; Cardona, A.; Boutureira, O.; Díaz, Y.; Matheu, M. I.

Abstract:
Supercritical carbon dioxide (scCO2) is a suitable medium to perform transition metal-free glycosylations in the absence of volatile organic solvents (VOCs) using glycosyl halides as glycosyl donors. The methodology here described can be applied for obtaining O-glycosides in a totally green reaction, as well as orthoesters, depending on the reaction conditions. The process is much more sensitive to temperature changes than to pressure modification, glycosyl chlorides requiring higher temperatures to be activated than glycosyl bromides. Pivaloyl groups act as good CO2-philic units and showed to be the best choice to obtain good stereoselectivities. The relevance of the fluid nature and supercritical conditions was also evidenced.