Methyl iodide → 1-Methyl-1H-indole-5-carboxylic acid

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Reaction Conditions

Reaction Steps

Under nitrogen atmosphere, a solution of indole-5-carboxylic acid (1.05 g) in DMF (40 mL) was cooled to 0° C., and thereto was added NaH (544 mg, 60%), and the mixture was stirred at the same temperature for 10 minutes, and stirred at room temperature for 30 minutes. The mixture was cooled to 0° C., and thereto was added iodomethane (3.68 g), and the mixture was stirred at room temperature for 48 hours. Water was added to the mixture, and the mixture was extracted three times with ethyl acetate-toluene, and dried over MgSO4. The solvent was evaporated under reduced pressure to give a crude methyl 1-methylindole-5-carboxylate. To a solution of the crude methyl 1-methylindole-5-carboxylate in THF (50 mL)-MeOH (50 mL) was added a 6N NaOH solution (5.4 mL), and the mixture was stirred at room temperature for 144 hours. The solvent was evaporated under reduced pressure. The residue was washed with ethyl acetate, and thereto was added a 6N aqueous hydrochloric acid solution to adjust the pH value thereof to pH=5-6. The mixture was extracted twice with ethyl acetate, and dried over MgSO4. The solvent was evaporated under reduced pressure to give 1-methyl-1H-indol-5-carboxylic acid (1.08 g, 96%).

Provenance & Evidence