Synthesis of Polysubstituted Thiophenes via Base‐Induced [2+2+1] Cycloaddition Reaction of Alkynes and Elemental Sulfur

A simple approach to polysubstituted thiophene derivatives is demonstrated. The synthesis is highlighted by the direct [2+2+1] cycloaddition reaction to construct carbon‐sulfur and carbon‐carbon bonds, without adding oxidizing, reducing and noble metal agents. All tested substrates provided their corresponding thiophene products in high isolated yields under the optimized conditions. magnified image