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

A copper-catalyzed C-S bond-forming reaction of <i>o</i>-halophenylacetylenes selectively affords <i>anti</i>-bisbenzo[<i>b</i>]thieno[2,3-<i>b</i>:2',3'-<i>e</i>][1,4]dithiins (<i>anti</i>-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, <i>anti</i>-BBTD derivatives with benzoyl substituents exhibit strong fluorescence and redox reversibility, which indicates their potential as optoelectronic materials.