General procedure for the synthesis of 1-iodo-2-naphthol from 2-hydroxy-1-naphthalenecarboxylic acid: 2-hydroxy-1-naphthalenecarboxylic acid (37.6 mg, 0.2 mmol), N-iodosuccinimide (NIS, 47.3 mg, 0.21 mmol), palladium acetate (0.9 mg, 0.002 mmol), and a stirrer were added to the reaction tube. Under the protection of inert gas, 1 mL of N,N-dimethylformamide (DMF) was added to the reaction tube as a solvent, followed by sealing the reaction tube. The reaction tube was placed in an oil bath at 80°C and the reaction was stirred for 3 hours. Upon completion of the reaction, the reaction mixture was cooled to room temperature and the pH was adjusted to 10 with 2 mol/L sodium hydroxide solution.The reaction mixture was diluted with 5 mL of water and extracted with ethyl acetate (5 mL x 3). The organic phases were combined, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure. The crude product was purified by column chromatography using ethyl acetate and petroleum ether (0:1 to 1:30, v/v) as eluent to give pure 1-iodo-2-naphthol (33.0 mg, 61% yield).
