Synthesis
A catalytic amount of 4-dimethylaminopyridine (DMAP) and di-tert-butyl dicarbonate (Boc2O, 5.9 g, 27.1 mmol) were sequentially added to a stirred solution of 4-nitroindole (4.0 g, 24.6 mmol) in dichloromethane (50 mL) at 0 °C. The reaction mixture was continued to be stirred at room temperature for 3 hours. After completion of the reaction, the reaction mixture was diluted with dichloromethane and washed with deionized water. The organic phase was separated and dried over anhydrous magnesium sulfate. The solvent was removed by concentration under reduced pressure to give 1-Boc-4-nitroindole as a white solid (6.14 g, 95% yield). Mass spectrum (ESI) m/z 262.1.
References
[1] Patent: US2009/227575, 2009, A1. Location in patent: Page/Page column 20
[2] Patent: US2010/36123, 2010, A1. Location in patent: Page/Page column 4; 5; 7; 8
