Synthesis
To the reaction solution, 4-aminoindole (2 g, 15.2 mmol), bis(2-chloroethyl)amine hydrochloride (3.2 g, 18.2 mmol) and potassium carbonate (4.2 g, 30.4 mmol) were added sequentially to isopropanol (30 mL). The reaction mixture was stirred at 90 °C for 48 hours. Upon completion of the reaction, the mixture was diluted by adding dichloromethane (50 mL) and methanol (50 mL) to the mixture. The reaction mixture was filtered to remove insoluble matter and the filtrate was concentrated under reduced pressure and dried by rotary evaporator. Finally, the residue was purified using silica gel column chromatography (eluent ratio of dichloromethane/methanol (v/v) = 10/1) to afford the target product 4-(1-piperazinyl)-1H-indole as a brown solid (2.78 g, 90.8% yield).
References
[1] Patent: CN105367472, 2016, A. Location in patent: Paragraph 0179; 0180; 0181; 0182
[2] Patent: US2008/318941, 2008, A1. Location in patent: Page/Page column 19-20
