Unexpected “reverse” cyclization of 2-mercaptobenzimidazole with chlorotrifluoroethylene and hexafluoropropene

[Display omitted] •The unusual behavior of fluorinated alkenes was observed.•New fluorinated hererocycles - benzimidazo[4,5b]thiazoles-1,3 were isolated.•The structures were supported by X-ray diffraction.•The possible reaction route was proposed. The unusual cyclization mode of 2-mercaptobenzimidazole with chlorotrifluoroethylene and hexafluoropropene has been found. Such unexpected products as 2-chloro-2,3,3-trifluoro-2,3-dihydrobenzimidazo[4,5b]thiazole-1,3 and 2-trifluoromethyl-2,3,3-trifluoro-2,3-dihydrobenzimidazo[4,5b]thiazole-1,3 were isolated. The structures of obtained compounds were supported by single crystal X-ray diffraction analysis and the possible reaction route was proposed.