To a solution of 2-chloro-5-fluorophenol (959 mg, 6.54 mmol) in N,N-dimethylformamide (DMF, 15 mL) was added 60% sodium hydride (NaH, 496 mg, 12.4 mmol) in batches at 0 °C. After the hydrogen bubbling stopped, iodomethane (0.43 mL, 6.91 mmol) was added and the reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, the mixture was slowly poured into a beaker containing water and crushed ice, alkalized with saturated aqueous sodium bicarbonate (NaHCO3) and extracted with dichloromethane (DCM). The organic phases were combined, washed with brine, dried over anhydrous sodium sulfate (Na2SO4) and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography using hexane:ethyl acetate (9:1) as eluent to afford 1-chloro-4-fluoro-2-methoxybenzene (600 mg) as a colorless oil. High performance liquid chromatography (HPLC, 254 nm) retention time (Rt): 6.15 min. 1H nuclear magnetic resonance (NMR, 600 MHz, DMSO-d6) δ ppm: 3.86 (s, 3H), 6.76-6.85 (m, 1H), 7.10 (dd, J = 10.90, 2.84 Hz, 1H), 7.45 (dd, J = 8.70, 6.14 Hz, 1H).
