A New Synthesis of Benzimidazolones, Benzoxazolones and Benzothiazolone from o-Substituted Nitrobenzenes Using Sulfur and Carbon Monoxide

Abstract

Selective and facile synthesis of benzene ring-substituted benzimidazolones, benzoxazolones and benzothiazolone was successfully accomplished in good yield by reductive carbonylation of the corresponding o-substituted nitrobenzenes with elemental sulfur, carbon monoxide and water in the presence of triethylamine.
The reaction of elemental s u lfur with carbon monoxide in the presence of triethylamine may initially afford carbonyl sulfide, which reacts with water to give the mixture of hydrogen sulfide and carbon dioxide under the reaction conditions.
Therefore, the present reactions probably took plac e through initial reduction of the starting nitrobenzenes with hydrogen sulfide followed by intermolecular cycloaddition of the resulting aniline derivatives with carbonyl sulfide generated in situ under the reaction conditions.
The reaction did not occur in the absence of either triethylamine or water.