Anodic coupling reactions and the synthesis of C-glycosides

A convenient, two-step procedure has been developed for converting sugar derivatives into C-glycosides containing a masked aldehyde functional group. The chemistry takes advantage of an anodic coupling reaction between an electron-rich olefin and an alcohol. The sequence works for the formation of both furanose and pyranose derivatives if less polarized vinyl sulfide derived radical cation intermediates are used. With more polarized enol ether derived radical cations, the cyclizations work best for the formation of furanose derivatives where the rate of five-membered ring formation precludes elimination reactions triggered by the radical cation.