Microwave-assisted synthesis of pyrazolyl bistriazines

Reaction of 6-chloro-N,N′-bispyrazolyl-1,3,5]triazine-2,4-diamines with 4-aminobenzylamine under microwave irradiation produces bistriazines in excellent yields. The use of a diamine bearing amino groups with different reactivities allowed the reaction to be carried out in two steps and selectively gave monotriazines, bistriazines with identical substituents and differently substituted bistriazines. The structures of these new compounds have been studied by NMR spectroscopy, mass spectrometry and in one case by X-ray crystallogrphy. These new bistriazines have promising applications in supramolecular chemistry based on hydrogen bonds and/or complexation with metals. The presence of a rigid linker can be used for the efficient preparation of extended supramolecular polymers with interesting fluorescence properties by complexation with cyanuric and barbituric acid derivatives.