Synthesis of 1-Halophenyl-pyrazolophthalazine derivatives and evaluation of their antimicrobial activity.

Background: Multi-component reactions for the preparation of pyrazolophthalazine derivatives under microwave irradiation from different aromatic aldehydes with a mixture malononitrile and phthalhydrazide derivatives were established. The antimicrobial activity of the target compounds was evaluated against four bacteria and two fungi using standard antibiotics Ampicillin and mycostatine as reference drugs. The structure-activity relationship studies reported that the substitution at 2,4, and 2,5-positions in the 1H-pyrazolo nucleus with the specific halogen atom increases the ability of the molecule against the antimicrobial activity. The structures of the synthesized compounds were established based on spectral data, IR, 1H NMR, 13C NMR and MS data.

Objectives: Design a series of new pyrazolophthalazine moieties and study the antimicrobial activity of these compounds Materials and Methods: pyrazolophthalazine derivatives 4a-j were synthesized by reaction of phthalhydrazide (1) with malononitrile (2), and various halogen aromatic aldehydes 3a-j in and EtOH/ Pip. Solution under microwave irradiation settings for two minutes at 140 °C Results: In this study, the antimicrobial activity of the synthesized compounds 4a-j was examined for their in vitro antimicrobial activity by using the agar diffusion method using Mueller-Hinton agar medium for bacteria and Sabouraud's agar medium for fungi. Ampicillin and mycostatine were included in the experiments as reference drugs.

Conclusion: A series of new pyrazolophthalazine derivatives were synthesized in this work. All compounds were evaluated for antimicrobial activity.