Synthesis and Antiproliferative Activity in vitro of New 2-Aminobenzimidazole Derivatives. Part 3 [1]. Reactions of 2-Arylideneaminobenzimidazole with Selected 1,3-Diketones

A series of pyrimido[1,2-a]benzimidazole derivatives has been synthesized in the reactions of 2-aminobenzimidazole Schiff bases 1-6 with selected β-diketones; acetylacetone 7-12 or benzoylacetone 13-18. The structures 4, 7-18 were confirmed by the results of elemental analysis and their IR, 1 H NMR and MS spectra. Compounds 4, 7-18 were examined for their antiproliferative activity in vitro against 3 cancer cell lines: P338 (mice leukemia), A549 (non-small cell lung carcinoma), SW707 (rectal adenocarcinoma), using SRB (sulphorhodamine B) or MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) technique. The Schiff base 4 and tricyclic derivatives 9, 14, 16 exhibited the highest cytotoxic activity in vitro.