Direct C-Glycosylation of Organotrifluoroborates with Glycosyl Fluorides and Its Application to the Total Synthesis of (+)-Varitriol

A mild, stereoselective, and quick approach to accessing alkynyl and alkenyl C-glycosides via BF3 center dot Et2O promoted coupling of organotrifluoroborates and glycosyl fluorides is reported. The application of this method was further demonstrated by the concise and efficient total synthesis of (+)-varitriol in only seven steps.