Antagonistic Effect of Acetates in C–N Bond Formation with In Situ Generated Diazonium Salts: A Combined Theoretical and Experimental Study

Abstract

The mechanism of the copper-catalyzed arylation of nitrogen heterocycles using anilines via diazonium salts has been studied by combining DFT and experimental data. A CuI/CuIII redox mechanism is proposed. Our study has revealed the multiple roles of the acid/base couple AcOH/AcO–. An in situ formed triazene species maintains a low concentration of diazonium salts in the reaction medium, which ensures limited formation of decomposition products. The results of DFT calculations have explained the lower reactivity of imidazole nucleophiles as compared with pyrazole in the arylation reaction.