Synthesis of compound 1.2. 2-Bromo-4-fluoroanisole (100 g, 487.75 mmol, 1.00 equiv) and THF (1.5 L) were added to a 3000 mL three-necked round-bottomed flask under nitrogen protection. With stirring at -78 °C, n-butyllithium (n-BuLi, 215.6 mL) was added slowly and dropwise. The reaction mixture was continued stirring at -78 °C for 1 hour. Subsequently, N,N-dimethylformamide (DMF, 71.54 g, 978.79 mmol, 2.01 eq.) was added slowly and dropwise at the same temperature. The reaction system was warmed up to room temperature and stirred for 1 hour. Upon completion of the reaction, the reaction was quenched by the addition of 800 mL of aqueous ammonium chloride (NH4Cl aq.). The reaction mixture was extracted with 500 mL of ethyl acetate, the organic layers were combined and concentrated under reduced pressure. The crude product was purified by column chromatography to afford 65.7 g (87% yield) of 5-fluoro-2-methoxybenzaldehyde (1.2) as a light yellow solid.
