Gold‐Catalyzed Formal Cyclisation/Dimerization of Thiophene‐Tethered Diynes

A new pathway in dual gold-catalyzed reaction of thiophene-tethered diynes has been identified. A series of fully conjugated alkynyl-substituted benzothiophenes and benzofurans was obtained by a formal cyclisation/dimerization sequence. All the products are fluorescent, owing to their extended conjugation. The mechanistic studies have been carried out, suggesting that gold acetylides take part in this transformation.