Electrochemical Synthesis of 4-Aryl-2-styryl-1H-benzo[b][1,4]diazepines from o-Phenylenediamine and 1,5-Diarylpenta-2,4-dien-1-ones

Diazepine is a seven-membered heterocyclic compound with two nitrogen atoms. Some ofdiazepine derivatives are psychoactive drugswhose core chemical structure is the diazepinering system. The first such drug, chlordiazepoxide (Librium), was discovered accidentallyin 1955, and they are usually useful for insomnia [1]. The common procedure for the synthesisof these compounds is a one pot condensation between o-phenylenediamines and α,β-unsaturated carbonyl compounds in the presence of catalysts[2, 3]. In this study, we report asynthesis of 1,4-diazepine derivatives under mild conditionsvia a metal and oxidant-free anodicoxidation in an undivided cell at room temperature. This environmentally benign approachafforded 4-aryl-2-styryl-1H-benzo[b][1,4]diazepines in satisfactory yields by using acheap pencil graphite and a Nickel electrode. The structure of products was characterized byNMR, IR, and mass spectral data.