Anodic oxidation of organic nitrogen compounds. Part I. Cyclization of 1-arylmethylenesemicarbazides

Abstract

The anodic oxidation of a number of 1-arylmethylenesemicarbazides (I) has been examined in acetonitrile–acetic acid containing sulphuric acid. The reactions were very sensitive to the concentration of water; under ordinary conditions the oxadiazole being formed in high yield, while stringent exclusion of water by introducing acetic anhydride into the solvent system resulted in the formation of the corresponding triazolinones. Rapid-sweep cyclic voltammetry showed that the cyclizations are extremely rapid. The ease of oxidation of the compounds (I) was sensitive to the para-substituent in the aryl group, electron-donating groups facilitating oxidation in the expected manner.