Silver-Catalyzed Thio-Claisen Rearrangement of Aryl Sulfoxides with AIBN

The Pummerer reaction represents a well-known transformation of sulfoxides. Mechanistically, this reaction is initiated by the generation of the thionium ion, whereas forming such intermediates typically requires the use of a stoichiometric amount of activating reagent. In this regard, we report the activator-free Pummerer-type transformation, a silver-catalyzed thio-Claisen rearrangement of aryl sulfoxides with AIBN. Facilitated by silver catalyst, AIBN is transformed into highly reactive ketenimine in situ, which directly captures the sulfoxides to generate thionium ion intermediates.