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Pyridazinones are widely recognized as versatile scaffolds with a wide spectrum of biological activities. In the present work, a series of new 4-chloro-2-(3-chloro-4-fluorophenyl)-5-(aliphatic/cyclic saturated amino)pyridazin-3(2H)-one derivatives 4a-i were synthesized and characterized by spectral techniques. The inhibitory effects of the synthesized compounds 4a-i on the viability of three human cancer cell lines, HEP3BPN 11 (liver), MDA 453 (breast), and HL 60 (leukemia), were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay. Among the compounds 4a-i screened, 4g and 4i exhibited inhibitory activity very close to the standard methotrexate; therefore, these lead compounds were further tested for their potential to inhibit the proangiogenic cytokines involved in tumor progression. Compound 4g was found to be a potent antiangiogenic agent against TNFα, VEGF, FGFb, and TGFβ, whereas 4i showed potent antiangiogenic activity against TNFα, VEGF, FGFb, and leptin. All the compounds 4a-i were screened for their antioxidant activities using 2,2-diphenyl-1-picryl hydrazine (DPPH), OH, and superoxide anion radicals. Compound 4f showed better OH radical scavenging activity than the standard ascorbic acid.

A catalytic method was developed to synthesize thiol esters from the reaction of acyl chlorides and thiols using zinc oxide as a catalyst under solvent-free conditions at room temperature. Mild reaction conditions, short reaction time, excellent yields of products and recyclability of the catalyst are noteworthy features of this methodology.

2,4,6-Trichloro-1,3,5-triazine-catalyzed convenient and efficient ring opening of epoxides with thiols under solvent-free conditions is described. Short reaction time, mild reaction conditions, inexpensive and readily available catalyst, and excellent yields of products are attractive features of this methodology.