Sodium Hydroxide → (5-Chloro-2-fluoro-4-((6-fluoro-1-methyl-3-indolylcarbonyl)amino)phenyl)acetic acid

In THF (17 ml) was dissolved ethyl (5-chloro-2-fluoro-4-((6-fluoro-1-methyl-3-indolylcarbonyl)amino)phenyl)acetate (665 mg, 1.63 mmol). To the resulting solution was added 0.25N NaOH (9.81 ml, 2.45 mmol) and the mixture was stirred at room temperature for 14 hours. The reaction mixture was poured in 1N HCl (3.0 ml). The crystals thus precipitated were collected by filtration under reduced pressure, washed with water, and dried under reduced pressure to give (5-chloro-2-fluoro-4-((6-fluoro-1-methyl-3-indolylcarbonyl)amino)phenyl)acetic acid (600 mg, 97%) as a brown solid.