2-(2-thienyl)-6-methyl-6H-imidazo[4,5-g][1,3]benzothiazole: Synthesis and some transformations

Oxidation of N-(1-methylbenzimidazol-5-yl)thiophene-2-carbothioamide with potassium ferricyanide in an alkaline medium by Jacobson’s method afforded 2-(thien-2-yl)-6-methyl-6H-imidazo[4,5-g][1,3]benzothiazole. The latter enters into the electrophilic substitution reaction (nitration, bromination, formylation, acylation) exclusively at the position 5 of the thiophene ring. Characteristic reactions of nucleophilic substitution occurred at the imidazole ring. Quaternization with methyl iodide in benzene furnished the corresponding quaternary salt, whereas the Chichibabin amination with an excess of sodium amide in xylene gave negative result.