General procedure: 300 mg (1.9 mmol) of 7-methoxyquinolin-2(1H)-one was dissolved in 1.1 mL of phosphorus oxychloride (POCl3, 12 mmol) and the reaction was heated to reflux for 3 hours. Upon completion of the reaction, the reaction mixture was slowly poured into ice water, neutralized to neutral with saturated sodium bicarbonate (NaHCO3) solution and subsequently extracted with ethyl acetate. After treatment, the target product 2-chloro-7-methoxyquinoline was obtained in 98% yield. The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 8.01 (d, J = 8.5 Hz, 1H), 7.68 (d, J = 8.9 Hz, 1H), 7.35 (d, J = 2.4 Hz, 1H), 7.25 (d, J = 8.3 Hz, 1H), 7.20 (dd, J = 8.9, 2.5 Hz, 1H), and 3.93 (s, 3H).
