Addition to Sulfur in Benzothiophenes

Benzomiophenium salts are produced by me reaction of me sulfur heterocycle with powerful alkylating reagents such as Meerwein salts benzomiophenium salts can themselves act as powerful alkylating agents 

5-Oxidation produces 1,1-dioxides, which readily undergo cycloadditions as dienophiles, or photodi-merisation, me head-to-head dimer being me major product. 5-Oxidation of me sulfur using a microbiological method gives the 5-oxide. ° 

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