Synthesis, Characterization and Biological Evaluation of 3‐Oxo‐pyrimido[1,2‐b]indazoles

The synthesis of substituted 3‐oxo‐pyrimido[1,2‐b]indazoles from 3‐aminoindazoles and ketones has been established. It involves one molecule of 3‐aminoindazoles and two molecules of ketones via a [3+2+1] three‐component annulation process. 3‐Oxo‐pyrimido[1,2‐b]indazoles exhibit strong yellow fluorescence in various solvents. A wide range of products have anti‐oxidant activities. Cytotoxicity studies indicate that compounds 3a, 3aa and 3ab have obvious effects on both HCT116 and A549 cancer cell lines.