catalytic amounts of several amines, N,N′-thiodiphthalimide has been allowed to react with one or two equiv. of arenesulfinicacids in dichloromethane, thus giving N-(arylsulfonylthio)phthalimides or bis(arenesulfonyl) sulfides respectively in good yields. The arenesulfinate anion seems to be a better nucleophile against N,N′-thiodiphthalimide than arenesulfinicacid. The mechanism of the catalytic reaction