Step 2: Synthesis of 2-hydroxy-4-(trifluoromethyl)benzaldehyde
2-Fluoro-4-(trifluoromethyl)benzaldehyde (5.00 g, 26.0 mmol, 1.00 equiv), water (5 mL), potassium carbonate (10.8 g, 78.1 mmol, 3.00 equiv), and DMSO (50 mL) were added to a reaction flask under nitrogen protection. The reaction mixture was stirred at 100 °C overnight. Upon completion of the reaction, the reaction was quenched with deionized water (70 mL). The reaction mixture was extracted with dichloromethane (3 x 100 mL), the organic phases were combined, washed with saturated saline (200 mL), dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography with the eluent of ethyl acetate/petroleum ether (6/94, v/v) to give 3.07 g of 2-hydroxy-4-(trifluoromethyl)benzaldehyde in 62% yield as a yellow oil.
