Thermolysis of 3-azidophenalen-1-ones to naphtho[8,1-ab]carbazolones and naphtho[8,1-ab]-8a-azonia-9-λ2-azafluoren-7-ones

Synthesis of blue light emitting heterocycles via cyclization of 2-pyridine derived 4-azido-r1,2,3-triazoles

An efficient synthesis of 2-pyridine derived 4-azido-1,2,3-triazoles was elaborated using the corresponding dichlorodiazadienes as precursors. The reaction of the prepared 2-azine substituted diazadienes with sodium azide permits the preparation of target triazoles isolated in up to 92% yield. Subsequent thermal cyclization was studied. Elimination of molecular nitrogen promoted the cyclization of nitrene at the azine nitrogen. As a result, a family of 2H-[1,2,3]triazolo[4',5':3,4]pyrazolo[1,5-a]pyridin-5-ium-4-ides was prepared. The synthesized compounds are members of a new heterocyclic system. Moreover, these compounds are new attractive blue light emitting molecules.

Study of the thermal behavior of azidohetarenes with differential scanning calorimetry

Thermal properties of azidohetarenes without reactive ortho-substituents, obtained by DSC analysis, were compared with the DSC data of ortho-phenyl and ortho-acyl substituted azidohetarenes, which give ring closure reactions either to indoles or to five-membered heterocycles such as isoxazoles. The reaction temperatures and reaction enthalpies give both information to prepare the reaction conditions and important safety information and were, in addition, used to find out relations between the temperatures or enthalpies with the three different reaction mechanisms.