Fused Triazolopyridazines: Synthesis, Characterization, Molecular Docking, and Anticancer Evaluation Against Breast Cancer Cell Line MDA‐MB‐231

A series of fused [1,2,4]triazolo[4,3‐b]pyridazine derivatives was synthesized via hypervalent iodine‐mediated oxidative cyclization of hydrazone intermediates using iodobenzene diacetate under mild, metal‐free conditions. This method was applied to diverse 6‐(4‐nitrophenyl)‐substituted triazolopyridazines with various aryl and heteroaryl groups, producing the target compounds in good to excellent yields with broad substrate tolerance. All compounds were characterized by FT‐IR, 1 H NMR, 13 C NMR, and HRMS. Their antiproliferative activity was tested against the human triple‐negative breast cancer cell line MDA‐MB‐231 using the sulforhodamine B (SRB) assay. Compound 3c, containing a 3,4‐dimethoxyphenyl substituent, showed the highest activity, suggesting a beneficial effect of electron‐donating groups. Molecular docking against cancer‐related proteins showed favorable binding, especially with Topoisomerase IIα, though these computational results are preliminary and don't confirm the exact molecular target. This study presents an efficient synthesis strategy and identifies compound 3c as a promising lead for further biological and medicinal chemistry research.