Rhodium-catalyzed synthesis of diaryl sulfides using aryl fluorides and sulfur/organopolysulfides

Substituted pentafluorobenzenes react with sulfur to give bis(4-substituted 2,3,5,6-tetrafluorophenyl) sulfides in the presence of RhH(PPh ₃)₄, 1,2-bis(diphenylphosphino)benzene (dppBz), and tributylsilane. The reaction proceeds efficiently between room temperature and 80 °C. A comparative study of the reactivities of an organic trisulfide and a tetrasulfide showed notable substrate specificity. Di-tert-butyl tetrasulfide reacted with reactive aryl monofluorides and substituted pentafluorobenzenes. Di-tert-butyl trisulfide reacted with aryl monofluorides. The reactivity was explained on the basis of the difference in S-S bond energy.