Synthesis and in vitro cytotoxic activity of novel pyrazolo[1,5-a]pyrimidines and related Schiff bases

The reaction of 5-amino 3 (4 methoxyphenylamino)-N-aryl-1H-pyrazole-4-carboxamides 1a-c with ethyl acetoacetate 2 and 2-(4-fluorobenzylidene)malononitrile 6 yielded pyrazolo[1,5-a]pyrimidines 5a-c and 9a-c, respectively. On the other hand, Schiff bases 11a-f were obtained upon treatment of carboxamides 1a-c with some selected aldehydes 10a and b. The newly synthesized compounds were characterized and confirmed by analytical and spectroscopic data (IR, MS, H-1 NMR, and C-13 NMR). Pyrazolo[1,5-a]pyrimidines 5a-c and 9a-c and Schiff bases 11b-f were investigated for their cytotoxicity against four human cancer cell lines (colon HCT116, lung A549, breast MCF-7, and liver HepG2) according to SRB assay and the structure activity relationship was discussed.