Iodide catalyzed synthesis of 2-aminobenzoxazoles via oxidative cyclodesulfurization of phenolic thioureas with hydrogen peroxide

A convenient and efficient oxidative cyclodesulfurization of o-phenolic thioureas to 2-aminobenzoxazoles employing TBAI (tetrabutylammonium iodide)/H₂O₂ catalyst/reagent system is reported. The protocol utilizes and offers a number of desired features such as metal-free, base-free, simple operation, room temperature, low cost catalyst/reagent, no need for anhydrous and inert conditions. The approach is also applicable to a one-pot synthesis of 2-aminobenzoxazoles in an excellent yield starting directly from o-aminophenols and aryl isothiocyanates.