Methyl 3-bromo-2-(bromomethyl)benzoate (5.27 g, 17 mmol) obtained in Step 2 was dissolved in 50 mL of tetrahydrofuran and 40% aqueous methylamine solution (7.5 mL, 86 mmol) was added. The reaction mixture was stirred at room temperature for 2 hours. After completion of the reaction, the solvent was evaporated under reduced pressure. The resulting residue was diluted with water and extracted with ethyl acetate. The organic layers were combined, washed with saturated aqueous sodium chloride and dried over anhydrous magnesium sulfate. After filtration, the solvent was removed by concentration under reduced pressure. The residue was purified by silica gel column chromatography to afford 4-bromo-2-methylisoindolin-1-one (3.36 g, 87% yield).1H NMR (300 MHz, CDCl3) δ 7.68 (d, 1H, J = 7.9 Hz), 7.53 (dd, 1H, J = 7.9, 0.9 Hz), 7.26 (t, 1H, J = 7.9 Hz), 7.26 (t, 1H, J = 7.9 Hz) 4.20 (s, 2H), 3.11 (s, 3H).
