Total Synergistic Effect between Triflic Acid and Bismuth( III ) or Antimony( III ) Chlorides in Catalysis of the Methanesulfonylation of Arenes

A total synergistic effect between bismuth(III) or antimony(III) chlorides and triflic acid has been observed in the Friedel−Crafts methanesulfonylation of arenes and has resulted in the development of the first efficient catalytic systems usable for the methanesulfonylation of both activated and deactivated arenes. A proposed mechanism to explain the observed effects is also discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)