Derivatives of 2,4-diazaspiro[5.5]undecane-1,5,9-trione (or 1,3,5,9-tetraone) (3a-j) were synthesized via the condensation of N,N-dimethyl barbituric acid (1a) and 1,3-diethylthiobarbituric acid (1b) with penta-1,4-diene3-one derivatives (2a-e) using a microwave-assisted method. In this study, we aim to synthesize novel 2,4diazaspiro[5.5]undecane-1,5,9-trione (or 1,3,5,9-tetraone) derivatives and conduct in vitro anticancer experiments to assess the biological activity of the newly synthesized compounds and previously reported ones from the literature. Optimal reaction conditions were determined for both traditional and microwave methods, showing that the microwave-assisted approach provides short reaction times and high yields (7892%). The synthesized compounds were characterized using 1 H-NMR, 13 C-NMR, LC-MS, and elemental analyses, confirming their structures and all these compounds showed anti-cancer effects on liver adenocarcinoma cells at different levels.