Synthesis of Thiophene-Fused π-Systems from Diarylethylenes via C–H Thienannulation and Mechanistic Studies

Abstract A facile, catalyst- and additive-free C–H thienannulation for the construction of thiophene-fused π-systems has been reported. This efficient protocol utilizes diarylethylenes and elemental sulfur to furnish diverse products in up to 98% yield with broad functional group tolerance and low-cost. A thiolate anion-participated domino mechanism was proposed, and gram-scale synthesis validated its good scalability and practicability.