Electrosynthesis of benzimidazole-fused quinazolinones via a cascade addition-desulfurization-cyclization process

Abstract

The electrosynthesis of benzimidazole-fused quinazolinones from N-substituted o-phenylenediamines and isothiocyanates via a cascade addition-desulfurization-cyclization process was introduced. This electrochemical approach utilizes the mild and efficient non-metal oxidizing agent, NaI in sub-stoichiometric amounts as an electrolyte/mediator under open-flask conditions. A variety of benzimidazole-fused quinazolinones were prepared in moderate to excellent yields (30–98 %, 10 examples). Additionally, the optimal conditions were successfully applied to the synthesis of benzoxazoloquinazolinones and benzothiazolquinazolinones (30–72 %, 6 examples). This electrochemical process is scalable, while maintaining reaction efficiency even at the gram scale.