3-hydroperoxy-, 3-hydroxy- and 3-oxoisothiazole 1,1-dioxides have been synthesized by the sequence of oxidation reactions from N,N′-linked isothiazolium perchlorates with hydrogenperoxide, MMPP, and pyridinium dichromate. Isothiazolium salts without acceptor substituents did not give N-substituted sultams. Novel N,N′-bisazaheterocycles were investigated as inhibitors of acetylcholinesterase (AChE) and human leukocyte