Research on the chemistry of 2-hetarylbenzimidazoles. 4. Oxidation of 1-methyl-2-(5′-methyl-2′-hetaryl)benzimidazoles

The methyl group in 1-methyl-2-(5-methyl-2-hetaryl)benzimidazoles (hetaryl = furyl and thienyl) was oxidized. It was found that a salt of a carboxylic acid, which in an acidic medium loses carbon dioxide to give 1-methyl-2-(2-furyl)-benzimidazole, is formed when 1-methy1-2-(5-methyl-2-furyl)benzimidazole is treated with an aqueous solution of potassium permanganate. The carboxy derivative of thiophene is considerably more stable. Oxidation by means of selenium dioxide leads to the corresponding 5-formyl derivative. The structures of the compounds obtained were confirmed by data from the IR and PMR spectra.See 1] for Communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1089–1091, August, 1982.