Synthesis, DFT and biological studies of novel 3,6-dimethyl-1,8-diphenyl-diazocino[3,4-c:7,8-c’]bispyrazole

Abstract

The condensation reaction of 5-amino-3-methyl-1-phenylpyrazole-4-carboxaldehyde with enol lactone was carried out to get the expected compound involving translactonization type rearrangement. However, the reaction did not proceed as visualized and afforded rather unexpected compound 3,6-dimethyl-1,8-diphenyl-diazocino [3,4-c:7,8-c’]bispyrazole as a result of Friedlander condensation. The structure was confirmed by spectroscopic determination and further studied using density functional theory (DFT) calculations. The FT-IR and 1H NMR values were calculated and compared with those experimentally obtained in spectra. The frontier molecular orbitals (HOMO and LUMO) and molecular electrostatic potential were computed to determine the distribution of charge density and possible site for electrophilic and nucleophilic reactions. The newly synthesized compound was screened for their anti-inflammatory and antibacterial activities using formalin-induced paw edema and agar diffusion methods respectively. It was found to possess significant activities on animals models and against Gram-positive and Gram-negative bacteria.