5-Bromo-4-chloro-7H-pyrrolo[2,3-d]pyrimidine (3.0 g, 13 mmol) was dissolved in DMF (40 mL) at 0 °C and NaH (60% w/w in mineral oil, 720 mg, 18.1 mmol) was added slowly. The reaction mixture was stirred at 0 °C for 30 min under nitrogen protection. Subsequently, benzenesulfonyl chloride (1.7 g, 13 mmol) was added dropwise, and the reaction mixture was warmed to room temperature and stirring was continued for 2 hours. Upon completion of the reaction, water (200 mL) was added to induce precipitation. The precipitate was collected by filtration and dried under vacuum to afford 7-benzenesulfonyl-5-bromo-4-chloro-7H-pyrrolo[2,3-d]pyrimidine (4.9 g, 100% yield) as a white solid. The product was characterized by 1H NMR (DMSO-d6, 400 MHz): δ 8.85 (1H, s), 8.45 (1H, s), 8.19 (2H, d, J=8.7Hz), 7.81 (1H, t, J=7.4Hz), 7.70 (2H, t, J=7.8Hz).
![5-Bromo-4-chloro-7H-pyrrolo[2,3-d]pyrimidine](/CAS/GIF/22276-95-5.gif)
![7-Benzenesulfonyl-5-bromo-4-chloro-7H-pyrrolo[2,3-d]pyrimidine](/CAS/GIF/252723-17-4.gif)