K2S2O8 mediated metal free oxidative coupling of alcohols with 1,2-diaminobenzenes for synthesis of benzimidazoles, photophysical and DFT studies

Abstract

We report the K2S2O8 catalyzed oxidative coupling of 1,2-diaminobenzenes and primary alcohols for the synthesis of benzimidazoles under metal-free conditions by utilizing oxygen from air as terminal oxidant and water in reaction medium. Also, the challenging aliphatic alcohols showed good performance in synthesis of benzimidazoles. We also carried out a detailed exploration of the mechanism. The metal-free conditions, commercially available oxidant and good functional-group tolerance are the advantages of the present strategy. Further, we have studied the light emitting properties of benzimidazoles. The absorption and emission spectra's of the compounds 5a and 6m were experimentally and computationally analysed. Also, HOMO/LUMO distributions of compound 5a and 6m were elucidated theoretically. © 2023 Elsevier B.V.