General procedure for the synthesis of 5-chloro-2-trifluoromethylbenzaldehyde from (5-chloro-2-trifluoromethylphenyl)methanol: (5-chloro-2-trifluoromethylphenyl)methanol (347 mg, 1.66 mmol) was dissolved in dichloromethane (10 mL). Pyridinium chlorochromate (717 mg, 3.32 mmol) was added to the solution and the reaction mixture was stirred for 2 hours at room temperature. After the reaction was completed, the reaction solution was diluted with ether and stirring was continued for 1 hour. Subsequently, the reaction mixture was filtered to remove insoluble impurities and the filtrate was concentrated to remove solvent. Finally, the crude product was purified by silica gel column chromatography using a hexane solution of 10% ethyl acetate as eluent to afford 5-chloro-2-trifluoromethylbenzaldehyde as a colorless oil (285 mg, 82% yield).1H NMR (400 MHz, MeOH-d4) δ 10.33 (s, 1H), 7.90 (s, 1H), 7.69 (d, 1H, J = 8.4 Hz), 7.54 (d, 1H, J = 8.4 Hz).
