The general procedure for the synthesis of 7-bromo-2-chloroquinolin-2(1H)-one from 7-bromo-2-chloroquinoline was as follows: 7-bromo-2-chloroquinoline (5.0 g, 20.6 mmol) was dissolved in a mixed solvent of 5 M aqueous hydrochloric acid (133 mL) and 1,4-dioxane (14 mL) with stirring and heated to reflux for 2 hours. After completion of the reaction, it was cooled to room temperature, the precipitate precipitated was collected by filtration and washed with deionized water to afford 7-bromoquinolin-2(1H)-one as a colorless solid (4.3 g, 93% yield). The product was characterized by 1H NMR (400 MHz, DMSO-d6): δ 11.80 (s, 1H), 7.91 (d, J=8.0 Hz, 1H), 7.63 (d, J=8.0 Hz, 1H), 7.48 (d, J=8.0 Hz, 1H), 7.34 (dd, J=8.0, 4.0 Hz, 1H), 6.53 (d, J= 4.0 Hz, 1H).
