Ultrasound promoted protection of alcohols: An efficient solvent-free pathway for the preparation of silyl ethers in the presence of no additive

Various types of alcohols and phenols were rapidly protected by hexamethyldisilazane in good to excellent yields at room temperature using high-intensity ultrasound irradiation in the presence of no solvent or any additive. Good to excellent chemoselectivity was observed for competitive protection of hydroxyl groups in favor of sterically less hindered alcohols. Exclusive protection of phenols in the presence of aromatic amines was also demonstrated successfully.