The syntheses of a series of 1,3-dithiole-2-thione derivatives (3-6), bearing fused terthiophene or bis(2-thienyl)-2,5-furan units, are reported. These novel heterocycles are readily polymerized electrochemically to give stable electroactive materials. The target compounds were obtained in moderate to high yield via the cyclization of the corresponding diketones or hydroxyketones, using phosphorus pentasulfide or acidic conditions. The ketones 12 and 17 were prepared directly from their hydroxy precursors by treatment with MnO2. The trans configuration of diketone 20 was confirmed by X-ray crystallography.
Skabara, P. J., Serebryakov, I. M., Roberts, D. M., Perepichka, I. F., Coles, S. J., & Hursthouse, M. B. (1999). Novel terthiophene and bis(thienyl)furan derivatives as precursors to highly electroactive polymers. Journal of Organic Chemistry, 64(17), 6418-6424. https://doi.org/10.1021/jo990198+