The general procedure for the synthesis of ethyl 4-chloroquinoline-6-carboxylate from the compound (CAS:127286-04-8) was as follows: intermediate 41 (3 g, 13.8 mmol) was mixed with phosphorus trichloride (8 mL) and the reaction was stirred at 120 °C for 3 hours. Upon completion of the reaction, the solvent was removed by vacuum evaporation and subsequently quenched by adding crushed ice to the residue. Next, saturated aqueous sodium bicarbonate solution with ethyl acetate was added to the mixture to form a two-phase system. The organic and aqueous phases were separated and the aqueous phase was then extracted with ethyl acetate. All organic phases were combined, dried with anhydrous sodium sulfate, filtered to remove the desiccant, and the filtrate was evaporated under vacuum to remove the volatile components. Finally, the target product ethyl 4-chloroquinoline-6-carboxylate (2.19 g, 67% yield) was purified by silica gel column chromatography.
