Rhodium-Catalyzed Intramolecular Transannulation Reaction of Alkynyl Thiadiazole Enabled 5,n-Fused Thiophenes.

A method for the synthesis of a wide range of fused thiophenes, including those fused with lactams, lactones, or cyclic ethers, was developed from a rhodium-catalyzed intramolecular transannulation reaction of alkynyl thiadiazoles. This transannulation reaction provides an efficient platform for the construction of a variety of 5,n-fused thiophenes from readily available starting materials together with the release of molecular nitrogen.