10075-50-0

61350-62-7

143322-56-9

General procedure for the synthesis of benzyl (R)-2-(5-bromo-1H-indole-3-carbonyl)pyrrolidine-1-carboxylate from 5-bromoindole and benzyl (R)-2-(chlorocarbonyl)pyrrolidine-1-carboxylate: 5-bromoindole (15.7 g, 80.4 mmol) was added to a 500 mL four-necked flask with dichloromethane (140 mL). The temperature of the reaction system was lowered to 0 °C under cooling in an ice bath, and aluminum trichloride solid (16.1 g, 120.6 mmol) was slowly added, taking care to add it in batches and controlling the internal temperature between 0 and 5 °C. After addition, the reaction was continued to be stirred at 0~5°C for 1 hour. Subsequently, a dichloromethane solution of N-benzyloxycarbonyl prolyl chloride prepared in Example 1 was slowly added dropwise under the same temperature conditions. After the dropwise addition was completed, the reaction was continued to be stirred for 6 hours by keeping 0~5°C. At the end of the reaction, the reaction system was placed in an ice bath and the reaction was quenched by slowly dropping 90 mL of saturated ammonium chloride solution. The reaction mixture was filtered, the filtrate was separated and the organic phase was washed with saturated sodium bicarbonate solution and saturated brine sequentially. After the solvent was removed by concentration under reduced pressure, the resulting crude product was purified by recrystallization using a solvent mixture of ethyl acetate and n-heptane (1:1, v/v). The purified product was dried under vacuum at 60 °C for 8 h to afford (R)-3-(N-benzyloxycarbonylpyrrolidin-2-ylcarbonyl)-5-bromo-1H-indole (14.2 g) as a white solid in 83% yield and 99.2% HPLC purity.