Synthesis of novel pyrazoline-based bis(1,2,3-triazole) scaffolds via click chemistry

Abstract

A series of novel bis(1,2,3-triazoles) derivatives 7a–m were synthe­sized by the 1,3-dipolar cycloaddition (click-reaction) of 1-methyl-3,5-bis(2-(prop-2-yn-1-yloxy)phenyl)-4,5-dihydro-1H-pyrazole (5) with various aralkyl azides 6a–m in the presence of sodium ascorbate and copper sulphate with good yields. The required precursor 5 was synthesized by reacting (E)-1,3-bis(2-hydroxyphenyl)prop-2-en-1-one (3) with methylhydrazine hydrate via 2,2′-(1-methyl-4,5-dihydro-1H-pyrazole-3,5-diyl)diphenol 4, followed by reaction with propargyl bromide. The homogeneity of all the newly synthesized compounds was checked by TLC. The IR, NMR, mass spectral data and ele­mental analysis were in accord with the assigned structure. The title com­pounds were evaluated for their antibacterial activity against various bacterial strains, i.e., Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis; compounds 7f–7h and 7j were found to be mod­erately active against the bacteria, when compared with that of the standard drug. Furthermore, the same library of compounds was evaluated for their anti­oxidant activity using the nitric oxide radical scavenging activity. The results of the study showed that compounds 7e–7h and 7k–7m showed good radical scavenging activity.