Diaminooxosulfonium salts were prepared by alkylation of aminosulfoximines. Their reactions with dimsyl sodium gave the corresponding ylides and sulfoximines. The intramolecular rearrangement of the ylide led to ortho substitution bia an intermediate cyclohexadienoneimine. Hydrogen transfer, accompanying rearomatization and the subsequent action of a base gave a dihydrobenzoisothiazole derivative.