Selective Synthesis of anti -Bisbenzo[ b ]thieno[2,3- b :2′,3′- e ][1,4]dithiin via Copper-Catalyzed Domino Formation of Eight C–S Bonds

A copper-catalyzed C-S bond-forming reaction of o-halophenylacetylenes selectively affords anti-bisbenzo[b]thieno[2,3-b:2',3'-e][1,4]dithiins (anti-BBTDs). This approach features a domino thienannulation reaction, a mild temperature, an inexpensive copper catalyst, efficient formation of C-S bonds, and excellent functional group compatibility. A domino thienannulation mechanism involving sulfur anions has been elucidated by an intermediate trapping experiment and X-ray photoelectron spectroscopy measurements. Furthermore, anti-BBTD derivatives with benzoyl substituents exhibit strong fluorescence and redox reversibility, which indicates their potential as optoelectronic materials.