A Highly Efficient Copper-Catalyzed Method for the Synthesis of 2-Hydroxybenzamides in Water

An efficient copper-catalyzed synthetic method for the preparation of 2-hydroxybenzamides is described for the first time from 2-chlorobenzamide substrates using copper iodide/1,10-phenanthroline and a base, potassium hydroxide, in neat water. By using this reaction, a series of 2-hydroxybenzamides with functional groups such as fluoro, chloro, iodo, methoxy, amide, and alcohol have been obtained in 33-96% yield. Other aromatic 2-chloroarylamides such as naphthalene, pyridine, and thiophene are found to be equally compatible to the reaction. It is proposed that the reaction proceed via formation of copper-amide complex, which may facilitate the hydroxylation in water. Overall, the first report on copper-catalyzed hydroxylation reaction in water and first catalytic route for the synthesis of 2-hydroxybenzamides is presented. Simple purification procedure and convenience of employing low-cost reagents in neat water make this method practical and economical for the synthesis of 2-hydroxybenzamides.