Preparation of N-Substituted Diaza[12]annulenes

Significance

A simple one-pot synthesis of N-substituted diaza[12]annulenes has been devised. The reaction is brought about by refluxing N-(2,4-dinitrophenyl)pyridinium chloride with various amines (examples include six anilines and one aliphatic amine) in ethanol for 12 hours. Product yields range from modest to high. The proposed mechanism involves an initial nucleophilic addition of amine to the pyridinium ring, and subsequent ring opening of the dihydropyridyl ring. Substitution of the 2,4-dinitroaniline moiety by another equivalent of amine, followed by a second round of analogous mechanistic steps, results in cyclization. Proton NMR studies indicate that a diamagnetic current is present in the 12-membered ring, and cyclic voltammetry measurements showed the compounds to be electrochemically active in solution.