Deprotection of pinacolyl boronate esters via hydrolysis of intermediate potassium trifluoroborates

An efficient two-step procedure for the deprotection of pinacolyl organoboronate esters is described. Reaction with excess potassium hydrogen fluoride produces the corresponding stable, crystalline potassium organotrifluoroborate salts. Treatment of the trifluoroborates with either inorganic base or trimethylsilyl chloride and water affords the corresponding organoboronic acid in high yield. (c) 2005 Elsevier Ltd. All rights reserved.