A new approach for the ortho-substitution of anilines and for the synthesis of indolines

Intermolecular radical addition of a xanthate to a vinyl sulfanilide is followed by ring closure to the aromatic ring to give a dihydrobenzoisothiazole dioxide structure, which upon heating loses sulfur dioxide to give a 2-substituted aniline; in some examples, the presence of DBU during heating induces the formation of an indoline.