954255-04-0

169674-01-5

954255-04-0

General procedure for the synthesis of 5,6-difluoroindoline from 5,6-difluoroindole: 0.30 g (1.8 mmol) of 5,6-difluoroindole was dissolved in 10 mL of tetrahydrofuran (THF) under the protection of argon gas and 3.0 mL of 1 M borane-THF solution was added slowly and dropwise. Subsequently, the reaction mixture was heated to 70 °C and maintained for 2 h, after which it was cooled to room temperature. To the reaction mixture, 3 mL of methanol was added, followed by 5 mL of aqueous 4N hydrochloric acid solution, and the mixture was refluxed for 1 hour. Upon completion of the reaction, the organic phase was removed by evaporation and the aqueous phase was washed with dichloromethane (DCM) and then alkalized with 4N aqueous sodium hydroxide solution, followed by multiple extractions with ethyl acetate (EtOAc). The organic phases were combined, dried over anhydrous sodium sulfate, filtered and concentrated. The product was obtained as 160 mg in 47% yield. eSI-MS: m/z = 156 (M + H)+; HPLC-MS retention time (Method C): 0.73 min.