6-Bromo-1H-indol-4-amine

Synthesis

To 6-bromo-1H-indol-4-amine (3 g, 9.49 mmol) was added HCl solution (61.20 g, 167.86 mmol) of TiCl3 (7.32 g, 47.45 mmol). The reaction mixture was stirred at 25 °C for 16 hours. After completion of the reaction, the mixture was slowly poured into 2N aqueous NaOH solution (150 mL) and extracted with EtOAc (150 mL). The organic phase was dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (eluent: petroleum ether to petroleum ether/ethyl acetate = 5/1) to afford 6-bromo-1H-indol-4-amine (2 g, 36% yield) as a gray solid.1H NMR (CDCl3, 400 MHz) δ 8.10 (br s, 1H), 7.09-7.08 (m, 1H), 7.02 (d, J = 1.4Hz , 1H), 6.54 (d, J = 1.4Hz, 1H), 6.44-6.43 (m, 1H), 3.98 (br s, 2H).

References

[1] Patent: WO2016/168682, 2016, A2. Location in patent: Paragraph 0256
[2] European Journal of Medicinal Chemistry, 2001, vol. 36, # 2, p. 165 - 178