General procedure for the synthesis of 4-methoxy-2-quinolinone from 2-hydroxyquinolin-4(1H)-one: to a suspension of 2,4-dihydroxyquinoline (3.00 g, 18.6 mmol) and potassium carbonate (5.14 g, 37.2 mmol) in acetone (500 mL) was added dropwise dimethyl sulfate (2.1 mL). The reaction mixture was heated to reflux for 5 hours. Upon completion of the reaction, the solvent was removed by vacuum distillation and the residue was ground with an appropriate amount of water. The crude product was collected by filtration, washed with water and subsequently purified by grinding with methanol to afford 4-methoxy-2-quinolinone (1.76 g, 54% yield) as a white solid. The 1H NMR data of the product were in agreement with literature reports (Reisch et al., Arch. Pharm., 1980, 313, 751-755).
