Synthesis and cytotoxic evaluation of some new phthalazinylpiperazine derivatives

A new series of 1,4‐disubstituted phthalazinylpiperazine derivatives 7a–f , 12a–f and 20a–f were designed and synthesized in order to develop potent and selective antitumor agents. The target compounds were screened for their cytotoxic activities against A549, HT‐29 and MDA‐MB‐231 cancer cell lines in vitro. Among them, compounds 7a–f exhibited excellent selectivity for MDA‐MB‐231 with IC₅₀ values ranging from 0.013 µM to 0.079 µM. The most promising compound, 7e (IC₅₀ = 2.19 µM, 2.19 µM, 0.013 µM), was 9.3, 10, and 4.9 × 10³ times more active than vatalanib (IC₅₀ = 20.27 µM, 21.96 µM, 63.90 µM), respectively.