5-Nitroisatin

In the synthetic route, the nitro group at the 5-position provides a handle for subsequent reduction to an amino group, which is then functionalized to form the heterocyclic core of Tucatinib. The isatin scaffold contributes to the fused-ring system critical for HER2 receptor binding. Following these transformations, additional coupling reactions and functional group modifications are carried out to generate the final Active Pharmaceutical Ingredient. 5-Nitroisatin is a key intermediate employed to synthesize Tucatinib.