PPh₃/I₂ Promoted Synthesis of Unsymmetrical Disulfides from Sodium Sulfites and 2‑Mercaptobenzo Heterocyclics

A simple and efficient method for the synthesis of unsymmetrical disulfides is reported. Using sodium sulfites and 2-mercaptobenzo heterocyclic compounds as starting materials, the unsymmetrical sulfur–sulfur bonds could be quickly constructed in the PPh₃/I₂ reaction system under transition–metal-free conditions. This protocol has the advantages of mild reaction conditions, easily available starting materials, and wide substrate scope, showing potential synthetic value for the synthesis of a diversity of biologically or pharmaceutically active compounds.