Investigations on Superbase Mediated Reactivity of N-Tosylhydrazones with Aza-ortho-Quinone Methide Precursors

We have encountered a superbase-mediated chemoselective reaction of N-tosylhydrazones with aza-ortho-quinone methide precursors. When tosylhydrazone was treated with ortho-aminobenzyl alcohol in super basic conditions (KOH+DMSO), we observed the formation of 2-substituted quinoline. The reaction was found to be general, and by this method, mono-, di- and tri-substituted quinolines could be made. We could prove experimentally and theoretically that the reaction proceeded via the formation of an azine from the basic decomposition of N-tosylhydrazones. Finally, the reaction of tosylhydrazone with N-(2-(chloromethyl)phenyl)-4-methylbenzenesulfonamide (aza-ortho-quinone methide precursor) under super basic conditions afforded hydrazine substituted sulfonamides.