28737-33-9

91348-45-7

28737-33-9

General procedure for the synthesis of 3-bromoindole-2-carboxylic acid from ethyl 3-bromoindole-2-carboxylate: ethyl 3-bromoindole-2-carboxylate (54.40 g, 203 mmol) was dissolved in ethanol (600 mL), and a solution of water (50 mL) and sodium hydroxide (20.20 g, 505 mmol) was added, and the reaction was carried out at reflux for 1 hour. After completion of the reaction, the mixture was cooled and the sodium salt of the title compound was collected by filtration. The sodium salt was dissolved in water, acidified with aqueous 3N hydrochloric acid to pH < 7 and then extracted with ethyl acetate. The organic phases were combined, washed sequentially with water and saturated saline, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The resulting crude product was recrystallized with ethyl acetate to give the white solid product 3-bromoindole-2-carboxylic acid (47.1 g, 88% yield). Melting point 201-203°C.