920966-03-6

885500-55-0

920966-03-6

General procedure for the synthesis of 4-chloro-1H-pyrrolo[2,3-b]pyridine-5-carboxylic acid from ethyl 4-chloro-1H-pyrrolo[2,3-b]pyridine-5-carboxylate: to a solution of 4-chloro-1H-pyrrolo[2,3-b]pyridine-5-carboxylic acid ethyl ester (10.5 g, 46.7 mmol) in ethanol (84 mL), was added an aqueous 1 M sodium hydroxide solution ( 140 mL, 140 mmol) and the reaction mixture was stirred at 60 °C for 1.5 hours. Upon completion of the reaction, the mixture was cooled to 4 °C and acidified with 1 M aqueous hydrochloric acid to pH < 7. The precipitated solid was collected by filtration and washed with deionized water to afford 4-chloro-1H-pyrrolo[2,3-b]pyridine-5-carboxylic acid (9.0 g, 98% yield). The structure of the product was confirmed by 1H-NMR (DMSO-d6) δ: 6.62-6.64 (1H, m), 7.67-7.70 (1H, m), 8.71 (1H, s), 12.32 (1H, br s), 13.22 (1H, br s) and mass spectra (ESI) m/z: 195 (M-H)-.