76-02-8

183208-35-7

849068-61-7

The general procedure for the synthesis of 5-bromo-1H-pyrrolo[2,3-B]pyridine-3-carboxylic acid using 5-bromo-7-azaindole and trichloroacetyl chloride as starting materials was as follows: 5-bromo-7-azaindole (10.00 g, 50.75 mmol) was dissolved in dichloromethane (200 mL), followed by the addition of aluminum chloride (34.00 g, 254.99 mmol). stirred for 10 minutes at room temperature. Next, trichloroacetyl chloride (8.6 mL, 77 mmol) was added slowly and the reaction continued to be stirred at room temperature overnight. After completion of the reaction, the reaction mixture was slowly poured into ice water and filtered to collect the white solid. The filtrate was extracted with ethyl acetate (200 mL x 3). The organic phases were combined and concentrated to give a white solid. The solid was dissolved in water (125 mL), triethylamine (50 mL) was added and stirred at room temperature for 24 hours. At the end of the reaction, the solvent was concentrated to remove the solvent, the pH was adjusted to 5-6 with 1.0 M dilute hydrochloric acid, the product was collected by filtration and dried at 50 °C to give the final 5-bromo-1H-pyrrolo[2,3-B]pyridine-3-carboxylic acid (8.20 g, off-white solid) in 67.0% yield.