General procedure for the synthesis of 4-bromo-8-methylquinoline from 8-methyl-4-hydroxyquinoline: To a 100 mL round-bottomed flask was added 8-methyl-4-hydroxyquinoline (500 mg, 3.14 mmol, 1.00 equiv) and N,N-dimethylformamide (20 mL). Phosphorus tribromide (851 mg, 3.14 mmol, 1.20 eq.) was added slowly and dropwise with stirring at room temperature. The reaction mixture was stirred continuously for 15 hours at room temperature. Upon completion of the reaction, the reaction was quenched with an ice-water mixture (100 mL). Subsequently, the pH of the reaction solution was adjusted to 10 with 2 mol/L NaOH solution.The precipitated solid was collected by filtration to give 660 mg of 4-bromo-8-methylquinoline in 95% yield as a light yellow solid. Mass spectra (electrospray ionization, m/z) [M + 1]: 222 and 224.
