Synthesis, Characterization and Biological Evaluation of Heterocycles

A facile synthesis of pyrazole based 1,2,4,5-tetrazino[1,6-a]quinoline derivatives 11a-o have been synthesized through the reaction of compounds 9a-c and substituted hydrazines 10a-e in presence of conc. H2SO4 as a solvent under reflux at 80° for 3-4.5 hr. The reaction proceeded efficiently to get the desire product in excellent yields (74-86%). The structures of the title compounds were confirmed by FT-IR, 1H NMR, 13C NMR and mass spectrometry. The newly synthesized compounds were screened for their preliminary in vitro antibacterial activity against a panel of pathogenic strains of bacteria and fungi, antituberculosis activity against Mycobacterium tuberculosis H37Rv and antimalarial activity against Plasmodium falciparum. Most of them exhibited significant antibacterial activity as compared to the first line drugs. This work is useful for the research students and academia educations.