preparation | pyridine (0.30mL,3.54mmol) was added to the suspension of 5-bromo-1H-indole (2.72mmol) in anhydrous THF(6mL) at 0 ℃, trichloroacetyl chloride (0.40mL) was added dropwise through the feeding funnel within 1 hour, 3.54mmol) of THF(6mL) solution, then warm the reaction mixture to room temperature and stir overnight. The reaction mixture was quenched in 1MHCl, dried by Na2SO4, and concentrated under vacuum. The resulting solid was then dissolved in MeOH(54mL), and KOH was added, the reaction mixture was heated to reflux for 5 hours, then stirred at ambient temperature for 1 hour, and then concentrated under vacuum. The solids were purified by chromatography (SiO2,25% EtOAc/hexane) to give methyl 5-bromoindole-3-carboxylate, a white solid. |