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-1$H$-pyrazole-4-carboxamides \textbf{1a}--\textbf{c} with ethyl acetoacetate \textbf{2} and 2-(4-fluorobenzylidene)malononitrile \textbf{6} yielded pyrazolo[1,5-$a$]pyrimidines \textbf{5a}--\textbf{c} and \textbf{9a}--\textbf{c}, respectively. On the other hand, Schiff bases \textbf{11a}--\textbf{f} were obtained upon treatment of carboxamides \textbf{1a}--\textbf{c} with some selected aldehydes \textbf{10a }and\textbf{ b}. The newly synthesized compounds were characterized and confirmed by analytical and spectroscopic data (IR, MS, $^{1}$H NMR, and $^{13}$C NMR). Pyrazolo[1,5-$a$]pyrimidines \textbf{5a}--\textbf{c} and \textbf{9a}--\textbf{c} and Schiff bases \textbf{11b}--\textbf{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.