A significant rate enhancement was observed in the preparation of allyl and allenyl-C-glycosides from glycosyl acetate or methyl O-glycoside precursors when ultrasound irradiation was employed as an energy source. The C-glycosides were obtained in 77–96% yields in <20 min using TMSOTf as promoter. These results show that sonication provides rapid and efficient access to useful C-glycoside-based building blocks.
