Silver-Catalyzed\nThio-Claisen Rearrangement of Aryl\nSulfoxides with AIBN

The Pummerer reaction represents a well-known transformation\nof\nsulfoxides. Mechanistically, this reaction is initiated by the generation\nof the thionium ion, whereas forming such intermediates typically\nrequires the use of a stoichiometric amount of activating reagent.\nIn this regard, we report the activator-free Pummerer-type transformation,\na silver-catalyzed thio-Claisen rearrangement of aryl sulfoxides with\nAIBN. Facilitated by silver catalyst, AIBN is transformed into highly\nreactive ketenimine <i>in situ</i>, which directly captures\nthe sulfoxides to generate thionium ion intermediates.