Under nitrogen protection, 3-bromo-1H-pyrrolo[2,3-b]pyridine (175 mg, 0.89 mmol), tetrabutylammonium bromide (10 mg, 0.03 mmol), finely ground sodium hydroxide (107 mg, 2.67 mmol), and dichloromethane (5 mL) were added to a dry round-bottomed flask, and mixed by stirring. The reaction mixture was cooled to 0 °C in an ice bath, followed by slow dropwise addition of benzenesulfonyl chloride (0.142 mL, 1.11 mmol). After the dropwise addition, the reaction mixture was gradually warmed up to room temperature and stirred continuously at this temperature for 1 hour. Upon completion of the reaction, the reaction was quenched by the addition of water (6 mL) and extracted twice with dichloromethane. The organic layers were combined, washed sequentially with water and saturated sodium chloride solution and dried over anhydrous magnesium sulfate. The organic layer was concentrated under reduced pressure to give an orange solid crude product. The crude product was ground in pentane, filtered, washed with pentane and dried to give 294 mg of the target compound 3-bromo-1-(phenylsulfonyl)-1H-pyrrolo[2,3-b]pyridine in 98% yield. The product was characterized by 1H NMR (300 MHz, CDCl3) with the following chemical shift δ (ppm): 8.48 (dd, J = 1.5, 4.8 Hz, 1H), 8.24-8.17 (m, 2H), 7.82 (dd, J = 1.5, 8.0 Hz, 1H), 7.79 (s, 1H), 7.60 (dd, J = 7.5 Hz. 1H), 7.54-7.46 (m, 2H), 7.27 (dd, J = 4.8, 8.0 Hz, 1H).
![1-(Benzenesulfonyl)-3-bromo-1H-pyrrolo[2,3-b]pyridine](/CAS/GIF/880769-95-9.gif)