Water → (4-{[1-(5-chloro-2-methoxy-benzenesulfonyl)-1H-indole-6-carbonyl]-amino}-phenyl)-acetic acid tert-butyl ester

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Reaction Steps

A solution of {4-[(1H-indole-6-carbonyl)-amino]-phenyl}-acetic acid tert-butyl ester (0.20 g, 0.57 mmol) in toluene (2.90 mL) was treated with tetrabutylammonium hydrogensulfate (0.02 g, 0.05 mmol) and a 50% solution of NaOH in water (0.57 mL, 7.12 mmol). After stirring at room temperature for 5 min, 5-chloro-2-methoxybenzenesulfonyl chloride (0.21 g, 0.85 mmol) was added. The mixture was stirred for 2 hours, then poured over ice. The resulting slurry was extracted with ethyl acetate and the combined organic phases washed with brine, dried over magnesium sulphate and evaporated. The residue was purified by flash chromatography (heptane/ethyl acetate gradient) to yield (4-{[1-(5-chloro-2-methoxy-benzenesulfonyl)-1H-indole-6-carbonyl]-amino}-phenyl)-acetic acid tert-butyl ester as a light yellow oil, 0.26 g (81%), MS (ISP): m/e=555.2 (M+H).

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