Straightforward synthesis of a novel ring-fused pyrazole-lactam and in vitro cytotoxic activity on cancer cell lines

In this paper a straightforward synthesis of a novel pyrazole derivative is reported. Prominent feature of this synthetic process is a 1,3-Dipolar Cycloaddition of a suitable nitrile imine with an activated α,β-unsaturated lactam to afford directly and regioselectively the corresponding ring-fused pyrazole. Having obtained the central core of the synthetic target, a double stepwise functionalization with a "side chain" characterized by a terminal cyclic aliphatic amine was carried out. This molecular structure was designed to interact strongly with typical biological residues, and indeed it showed potent anticancer capability: in vitro cytotoxicity test on five different cancer cell lines showed interesting IC50 values in the range of 15-60 μM for exposure time of 24-72 h, thus resulting comparable with commercially available and nowadays therapeutically exploited anticancer compounds, such as 5-FU and NVP-BEZ235.