Access to β-acetoxyselenides, perhydroindolones and anticancer piperidinones via blue LED-driven selenylation of unsaturated carboxamides.

Blue LED-initiated selenylation of unsaturated acid amides with diorganyl diselenides in acetic and formic acids was shown to proceed either through a three-component conjugate addition to the double C=C bond, or via selenocyclization, depending on the N-substituent and solvent. The latter occurs as O-cyclization via the exo-trig mode to give iminolactones/lactones or as N-cyclization via the 5-exo-trig and 6-endo-trig modes to give selenyl-functionalized perhydroindolones and piperidinones, respectively. Among the synthesized compounds, the piperidinone derivative 12ea exhibited the greatest antiproliferative potency in human cervical carcinoma (HeLa) and human colorectal carcinoma (HCT-116) cells, with half-maximal inhibitory concentration (IC50) values in the micromolar range. Mechanistic studies revealed induction of apoptosis, confirmed by caspase-3/7 activation, Annexin V/propidium iodide staining, and nuclear abnormalities with γH2AX foci, consistent with DNA damage and mitotic stress. In three-dimensional spheroid models, 12ea effectively suppressed tumor-like growth and promoted apoptotic cell death. These findings identify 12ea as a promising and selective lead compound for further development in anticancer drug discovery.