766557-02-2

General procedure for the synthesis of 6-chloroindole-3-carboxylic acid from 1-(6-chloro-3-indolyl)-2,2,2-trifluoroethanone: b) 21.6 g (87.2 mmol) of 1-(6-chloro-1H-indol-3-yl)-2,2,2-trifluoroethanone was dissolved in 110 mL of aqueous 4 M potassium hydroxide solution and heated to reflux for 2 hours. Upon completion of the reaction, the reaction solution was cooled to 0 °C and neutralized with 36.7 mL of concentrated aqueous hydrochloric acid, at which point a white solid precipitated from the solution. The solid product was collected by filtration and washed with deionized water. Finally, the product was dried under high vacuum at 80 °C to give 16.4 g (96% yield) of 6-chloroindole-3-carboxylic acid as a light yellow solid. Mass spectrometry result: m/e 194 (M-H+, 100%).

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