Phthaloyl Dichloride–DMF Mediated Synthesis of Benzothiazole‐based 4‐Formylpyrazole Derivatives: Studies on Their Antimicrobial and Antioxidant Activities

Benzothiazole-based pyrazole derivatives prepared by a molecular hybridization approach with an aim to influence the biological activity significantly. Efficient conversion of hydrazones 3a-k derived from their corresponding methyl ketones to 4-formylpyrazoles 4a-k was carried out at 60 degrees C in dioxane, using the Vilsmeier-Haack reagent isolated from phthaloyl dichloride and N,N-dimethylformamide. The newly synthesized compounds 4a-k and hydrazones 3a-k were screened in vitro for their antimicrobial activities using the broth macrodilution method. The compounds 4a-k were also screened for their antioxidant activities using the DPPH radical scavenging assay. Some of the synthesized compounds showed significant antibacterial and antifungal activities as evident from their minimum inhibitory concentrations. Compound 4d showed remarkable antioxidant activity.