Synthesis of Sulfonylthiophenes through [3+2] Cycloaddition of Pyridinium 1,4-Zwitterionic Thiolates with (<i>E</i>)-β-Iodovinyl Sulfones or Bromoallylsulfones

A novel metal-free [3+2] cycloaddition strategy involving (<i>E</i>)-β-iodovinyl sulfones or bromoallylsulfones and pyridinium 1,4-zwitterionic thiolates for the efficient synthesis of sulfonylthiophenes is presented. This method exhibits good substrate tolerance, metal-free catalysis, and easily prepared bench-stable substrates. The findings highlight a practical metal-free protocol for accessing sulfonyl-substituted thiophenes with significant biological and chemical relevance, serving as an alternative to traditional metal catalysis and the oxidation of aryl/heteroaryl sulfides.