10.1080/00397910903318591
Indirubin derivatives are known for their high activity against various experimental solid tumors and their ability to inhibit cyclin-dependent kinases (CDKs) and glycogen synthase kinases-3 (GSK-3), which play important roles in diseases like cancers. The study explores a simple and convenient route involving oxidation and subsequent condensation of indoxyl and isatin. Acidic reaction conditions are crucial for the condensation of 4-substituted derivatives due to steric hindrance, while both acidic and basic conditions work well for 6-substituted derivatives. The authors successfully synthesized a range of 4- and 6-substituted indirubin derivatives and confirmed their structures using various spectroscopic techniques. The findings provide a novel approach to synthesizing these potentially therapeutic compounds, which could have significant implications for cancer treatment and other related diseases.