The general procedure for the synthesis of tert-butyl 5-amino-3-iodo-1H-indole-1-carboxylate from 3-iodo-1H-indole-5-cyano and di-tert-butyl dicarbonate was as follows: 5-cyano-3-iodoindole (0.700 g, 2.61 mmol) was dissolved in dichloromethane (40 mL), and di-tert-butyl dicarbonate (0.627 g, 2.87 mmol) was added sequentially, triethylamine (1.09 mL, 7.83 mmol) and 4-dimethylaminopyridine (32.0 mg, 0.261 mmol). The reaction mixture was stirred at room temperature for 40 min. After completion of the reaction, the reaction mixture was diluted with ethyl acetate and washed sequentially with 1 mol/L hydrochloric acid and saturated brine. The organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give 1-tert-butoxycarbonyl-5-cyano-3-iodoindole (0.958 g, quantitative yield). esi-ms: m/z 369 [M + H]+.
