Synthesis of azobenzenes with high reactivity towards reductive cleavage: Enhancing the repertoire of hypersensitive azobenzenes and examining their dissociation behavior

Abstract

Trifluoromethyl (CF3), cyano (CN), and nitro (NO2) groups were demonstrated to be effective acceptors in the molecular design of triple-donor/acceptor-based hypersensitive azobenzenes. The synthesis of these reactive scaffolds requires only two steps with overall yields ranging from 70 to 73%. UV–Vis absorption spectroscopy indicated that in all cases, a few seconds of exposure to mild reducing conditions is sufficient for complete cleavage of the azo bond. Liquid chromatography coupled with mass spectrometry (LC-MS) established the formation of two aniline fragments in the case of the CF3 and CN-substituted azobenzenes. In the case of the NO2-substituted compound, however, partial reduction of the nitro group results in the formation of three different anilines.