Fused-Ring Systems Containing 1,2,4-Benzothiadiazines. I. The Reaction of o-Aminobenzenesulfonamides with Dibasic Acid Anhydrides

New Derivatives of 3,4-Polymethylene-1,2,4-benzothiadiazine S,S-Dioxides

“…We then attempted to use another route for synthesizing salts interesting to us. We hoped that the sequential reduction of thiadiazine dioxide 7a, alkylation of the hexahydro derivative in basic medium [3,7], and oxidation of the product obtained would lead to the required quaternary salt. In reality, compound 7a is readily reduced with lithium aluminum hydride to the hexahydro derivative 8, which gives the N-methyl derivative 9 on alkylation with dimethyl sulfate in alkaline medium.…”