4-fluoro-1H-indole-7-carboxylic acid

313337-33-6

313337-34-7

Step B: Potassium hydroxide (13.04 g, 0.232 mol) was dissolved in a 14% water/ethanol mixture (50 ml) and 4-fluoro-1H-indole-7-carbonitrile (900 mg, 5.60 mmol) was added. The reaction mixture was refluxed for 12 h followed by slow cooling to room temperature and concentrated under vacuum to about 30 ml. The residue was acidified to pH 2 with an aqueous hydrochloric acid solution of about 5.5 N. The precipitate was collected by filtration, washed with excess water and dried under high vacuum to give 4-fluoro-7-carboxyindole as a white solid (100% conversion). The resulting product can be used in subsequent reactions without further purification.