Methyl iodide → 6-bromo-5-fluoro-1-methyl-1H-indole

To the solution of 6-bromo-5-fluoro-1H-indole (0.92 g, 4.28 mmol) in dry DMF (10 mL) was added sodium hydride as 60% in oil (0.26 g, 6.41 mmol) at 0° C. The mixture was stirred at 0° C. for 30 min, and then iodomethane (0.32 mL, 5.14 mmol) was added. The mixture was stirred for 1 hour at room temperature, and then quenched with ice and extracted with EtOAc (50 mL). The organic layer was washed with water, brine, dried over MgSO4, filtered, and concentrated. The residue was purified by column chromatography (EtOAc-hexane, 1:9) give 6-bromo-5-fluoro-1-methyl-1H-indole as a colorless solid (0.97 g, 99%). 1H NMR (CDCl3, 400 MHz): 3.66 (s, 3H), 6.43 (d, J=2.7 Hz, 1H), 7.05 (d, J=2.7 Hz, 1H), 7.34 (d, J=9.3 Hz, 1H), 7.44 (d, J=5.4 Hz, 1H).