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

Abstract 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 3 a , 3 aa and 3 ab have obvious effects on both HCT116 and A549 cancer cell lines.