Unusual difluoromethylation of 2-mercaptoazoles

The conditions for difluoromethylation of 2-mercaptobenzimidazoles with difluorocarbene (CHClF2 in alkaline medium) at the sulfur atom or at two reaction centres — sulfur and nitrogen or two nitrogen atoms — were found. In the similar reaction, 2-mercapto-4(5)-(4-nitrophenyl)imidazole gives the product of bis(difluoromethylation) at the sulfur and nitrogen atoms. Benzimidazoles with two fluorinated alkyl substituents at the two nitrogen atoms were prepared for the first time. The N-difluoromethyl derivative of benzothiazole-2-thione was obtained by this procedure.