2-Chloro-6-ethoxyquinoline-3-carboxaldehyde is a useful research chemical for the preparation of coumarin hydrazide-?hydrazone derivatives as it is being studied and has shown to have antitumor activities against resistant pancreatic carcinoma (Panc-?1)?, hepatocellular carcinoma (HepG2) and leukemia (CCRF) cell lines.