Synthesis and antitumor activity studies of some new fused 1,2,4-triazole derivatives carrying 2,4-dichloro-5-fluorophenyl moiety

A series of 3-(2,4-dichloro-5-fluorophenyl)-6-(substituted phenyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines (4) (Fig. 1) have been synthesized by the cyclization of 3-(2,4-dichloro-5-fluorophenyl)-1,2,4-triazol-5-thiol (3) with substituted phenacyl bromides. All the newly synthesized compounds were confirmed by IR, ¹H NMR and mass spectral studies. Among the compounds tested for their antitumor activity three compounds exhibited in vitro antitumor activity with moderate to excellent growth inhibition against a panel of sixty cancer cell lines of leukemia, non-small cell lung cancer, melanoma, ovarian cancer, prostate and breast cancer. The compound 4d showed promising antiproliferative activity with GI₅₀ values in the range of 1.06-25.4 μM.