172078-33-0

1953-54-4

172078-33-0

General procedure for the synthesis of 5-hydroxyindoline from 5-hydroxyindole: 0.34 g of sodium cyanoborohydride was added in batches to a 6.0 mL solution of glacial acetic acid containing 0.60 g (4.5 mmol) of 5-hydroxyindole under nitrogen protection. The reaction mixture was stirred at room temperature for 60 minutes. Subsequently, the reaction mixture was poured into 4 N aqueous sodium hydroxide solution and extracted with ethyl acetate (EtOAc). The combined organic phases were washed several times with saturated sodium bicarbonate solution, dried over anhydrous sodium sulfate and subsequently concentrated under reduced pressure. The product 265 mg was obtained in 35% yield of the theoretical value. The product was detected by ESI-MS, m/z = 136 (M + H)+; HPLC-MS retention time (Rt): 0.38 min (Method C).