Ethylene glycol, an efficient and recoverable medium for copper-catalyzed <i>N</i>-arylation of diazoles under microwave irradiation

<p>Ethylene glycol was used as an efficient and recoverable medium for the reaction of diazoles with aryl iodides and aryl bromides in the presence of CuCl<sub>2</sub> as the catalyst and K<sub>2</sub>CO<sub>3</sub> as the base. Consequently, imidazole, benzimidazole, and pyrazole reacted readily under microwave irradiation to give good to excellent yields of their corresponding <i>N</i>-arylated products in relatively short time periods. Apparently, ethylene glycol plays a dual role by activating the catalyst and also providing a homogenous medium for the processes. The reaction medium consisting of the solvent, the base, and the copper salt was recovered and reused successfully in the next several reactions.</p>