Copper-Catalyzed Direct C2-Silylation of Glycals: Application in the Synthesis of 2-Silyl Ferrier Glycosides.

We present here a copper-catalyzed, radical-mediated silylation of glycals as the first general method for direct, regioselective C2 silylation, providing unprecedented access to C2-silylated sugar scaffolds under mild conditions. The inexpensive protocol accommodates diverse protecting groups and glycosides. Also, a wide range of commercially available silyl groups could be incorporated under the current protocol. The resulting C2-silylated glycals serve as versatile platforms for Ferrier-type O-, C-, and S-glycosylations, retaining the silyl functionality and enabling steric and conformational control. The utility of this new class of compounds has been demonstrated through further transformations, including epoxidation, dihydroxylation, hydrogenation, and others. This new class of glycosides with a silicon functionality at the C2 position can serve as a structurally novel class of glycomimetics.