Synthesis of Polytetrazines, Pyrazoles and Polypyrazoles Based on 1,3-Dipolar Cycloaddition

Background: The chemistry of tetrazine has gained an increased attention in the last decades due to their applications materials science and coordination chemistry. 1,3-Dipolar cycloaddition of nitrile imines to C60 is the standard method for annelating the pyrazoline ring to the fullerene sphere. The interest in the chemistry of hydrazonoyl halides is a consequence of the fact that they undergo a wide variety of reactions, which provide routes heterocyclic compounds. Results: A facile synthesis of polytetrazines based on bishydrazonoyl halides is described. Bis(pyrazolino[60] fullerenes) were synthesized from the reaction of bishydrazonoyl halides with [60]fullerene. Moreover, an efficient synthesis of new polypyrazoline-maleimide is reported. The synthetic methods involves 1,3-dipolar cycloaddition reactions of bisnitrilimines (generated in situ by the effect of the triethylamine on bishydrazonoyl halides) to give the final products. Structures of the newly synthesized products were elucidated via elemental analyses and spectral data (FT-IR, MS, 1H and 13C NMR). Conclusion: Novel heterocycles of polytetrazines, bis(pyrazolino[60]fullerenes) and Polypyrazoline-maleimide based on 1,3-dipolar cycloaddition reaction are reported.