Step 1: Synthesis of 3-bromo-5-chloro-1H-pyrrolo[2,3-b]pyridine. N-bromosuccinimide (1.08 g, 6.1 mmol) was slowly added to a solution of N,N-dimethylformamide (DMF, 25 mL) containing 5-chloro-1H-pyrrolo[2,3-b]pyridine (0.85 g, 5.5 mmol) and the reaction was stirred for 4 h at room temperature. Upon completion of the reaction, the reaction was quenched by the addition of water (100 mL) to the reaction mixture, followed by extraction with ethyl acetate (EtOAc, 3 x 50 mL). The organic phases were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure to remove the solvent. The crude product was purified by silica gel column chromatography (eluent: hexane/ethyl acetate gradient elution) to afford the title compound 3-bromo-5-chloro-1H-pyrrolo[2,3-b]pyridine (1.28 g, quantitative yield). The product was characterized by 1H NMR (400 MHz, DMSO-d6): δ 12.3 (br.s, 1H), 8.30 (d, J = X Hz, 1H), 7.93 (d, J = X Hz, 1H), 7.84 (s, 1H).
![3-bromo-5-chloro-1H-pyrrolo[2,3-b]pyridine](/CAS/GIF/866546-09-0.gif)