Selective Cleavage of tert-Butyldimethylsilylethers ortho to a Carbonyl Group by Ultrasound

A general method for the selective cleavage of tert-butyldimethylsilylethers ortho to a carbonyl group is established by sonication of a 0.1 M solution of the substrate in 1/1 (v/v) CH3OH/CCl4. Other phenolic tert-butyldimethylsilylethers are unaffected. This reaction performed on flavanoids is completed within 3 h and no special workup is required. Other substrates are also investigated and a mechanism is proposed.