The general procedure for the synthesis of tert-butyl (1H-indole-3-methyl)carbamate from di-tert-butyl dicarbonate and indole-3-methylamine was as follows: to a 500 mL four-necked flask were added indole-3-methylamine (21 g, 144 mmol), dichloromethane (200 mL), triethylamine (29 g, 288 mmol) and 4-dimethylaminopyridine (3.5 g, 29 mmol). A tetrahydrofuran solution of di-tert-butyl dicarbonate (35.5 g, 158 mmol) was added dropwise at room temperature. The reaction mixture was stirred at room temperature for 2 hours. Upon completion of the reaction, the mixture was washed with distilled water (100 mL x 2), dried over anhydrous sodium sulfate, concentrated under reduced pressure, and finally purified by column chromatography to afford the target product 3-(N-tert-butoxycarbonylaminomethyl)indole (15.9 g, 46% yield). The structure of the product was confirmed by 1H NMR (300 MHz, DMSO-d6): δ 10.87 (broad peak, 1H), 7.59 (single peak, 1H), 7.34 (single peak, 1H), 7.18-6.99 (multiple peaks, 4H), 4.26 (single peak, 2H), 1.39 (single peak, 9H).
