Empowering strategies of electrochemical N–N bond forming reactions: direct access to previously neglected 1,2,3-triazole 1-oxides

Abstract

Electrochemical synthesis has become one of the emerging and powerful tools to create novel state-of-the-art strategies for the assembly of complex organic molecules. However, electrochemically induced N–N bond forming reactions still remain challenging due to the relatively high electronegativity of nitrogen and various side reactions associated with the oxidation of N–H bonds. Herein, we present a novel green electrochemical approach for the selective intramolecular formation of N–N bonds via the oxidation of readily available oximinohydrazones. Hence, previously neglected nitrogen heterocycles, 1,2,3-triazole 1-oxides, were prepared through a sustainable transition-metal- and exogenous oxidant-free strategy with broad generality. Based on the obtained cyclic voltammograms and DFT calculations, a plausible mechanism for the oxidation of oximinohydrazones was proposed. According to differential scanning calorimetry (DSC) data, the prepared 1,2,3-triazole 1-oxides may be classified as thermally stable species (T_d: 151–242 °C), which are highly valuable for the further development of functional organic materials. Moreover, 1,2,3-triazole 1-oxides were found to exhibit promising NO release properties under physiological conditions, unveiling broad opportunities for the creation of new pharmaceutical ingredients in an environmentally benign fashion.