General procedure for the synthesis of 2-chloro-4-methoxybenzonitrile from 2-chloro-4-hydroxybenzonitrile and iodomethane: To a stirred solution of 2-chloro-4-hydroxybenzonitrile (2.5 g, 16 mmol) in DMF (25 mL) was slowly added NaH (0.431 g, 18.0 mmol) at 0 °C. After 30 min, iodomethane (3.47 g, 24.4 mmol), followed by continued stirring of the reaction mixture for 1 h at room temperature. After completion of the reaction, the reaction mixture was quenched with ice water and extracted with ether. The organic layer was washed sequentially with water and saturated NaCl solution, dried over Na2SO4 and concentrated in vacuum to afford the target product 2-chloro-4-methoxybenzonitrile as a brown solid (2.7 g, 98% yield).
