Ring formation from 2-arylazo-3-aminocrotononitriles to 1,2,3[2 H]-triazole-4-carbonitriles and pyrazoles by anodic oxidation

Abstract

Arylazo substituted enamines are converted at room temperature into 2-aryl]-1,2,3[2 H]-triazoles by galvanostatic anodic oxidation in acetonitrile in fair yields without the use of metal ions. Pyrazoles are formed as side products. Their yield can be increased in methanol as solvent, employing potentiostatic reaction conditions. Reaction mechanisms for the formation of the products are proposed, where the triazole formation constitutes a new intramolecular pathway for the anodic oxidation of enamines, while the pyrazole formation includes the participation of a non-oxidized enamine molecule.