1215-59-4

24424-99-5

170147-29-2

Step 1: To a solution of 5-benzyloxyindole (2 g, 8.98 mmol) in dichloromethane (DCM, 20 mL) was added sequentially triethylamine (EtsN, 3.7 mL, 26.91 mmol) and 4-dimethylaminopyridine (DMAP, 328 mg, 2.68 mmol) at 0 °C, followed by the addition of di-tert-butyl dicarbonate (Boc2O. 2.9 g, 13.45 mmol). After the addition was completed, the reaction mixture was stirred at room temperature for 16 hours. After completion of the reaction, the reaction mixture was diluted with dichloromethane, washed with water and saturated saline in turn, the organic phase was dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated to dryness. The crude product was purified by silica gel column chromatography (eluent: petroleum ether/ethyl acetate=50:1) to afford tert-butyl 5-(benzyloxy)-1H-indole-1-carboxylate (2.5 g, yield 86.08%) as a white solid. lC/MS (ESI) m/z: 268 ([M-Boc+H]+).