Facile synthesis of 1, 2‐benzisothiazole‐3‐one‐1,1 ‐dioxide methylsulfonyl derivatives

An improved and general synthesis of saccharin methylthio and methylsulfone derivatives from chlorosubstituted saccharins is presented. A large‐scale procedure for preparation of chloro‐substituted saccharins was developed. Treatment of the saccharin chlorides with sodium thiomethoxide and t‐BuOK in DMF gave the saccharin methyl sulfides, which upon chromium(VI) oxide catalyzed oxidation with periodic acid afforded the corresponding saccharin methylsulfones in high yields.