36132-08-8

5,7-Dibromo-1H-indole is an indole compound with two bromine atoms as substituents on the benzene ring. 5,7-Dibromo-1H-indole can participate in metalation reactions, the most common of which is lithiation. Other metals used in direct metalation or transmetalation of indoles include magnesium, zinc, tin, and boron. The structure is also known for directed metalation of nitrogen functional groups, directed orthorhombic metalation of substituents other than nitrogen, and halogen metal exchange.

Vinylmagnesium bromide (21.0 g, 160 mmol) was slowly added to a solution of 2,4-dibromo-1-nitrobenzene (15.0 g, 53.3 mmol) in tetrahydrofuran (THF, 150 mL) at -40°C and the reaction was stirred for 30 min maintaining the temperature at -40°C. Upon completion of the reaction, the reaction mixture was carefully poured into saturated ammonium chloride (NH4Cl, 300 mL) solution and extracted with ethyl acetate (EtOAc, 3 x 300 mL). The organic layers were combined, washed with saturated brine (200 mL), dried over anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure. The resulting crude product was purified by silica gel column chromatography (100-200 mesh, eluent 0 to 8% ethyl acetate in hexane solution) to afford 5,7-dibromo-1H-indole (5.90 g, 41% yield) as a brown solid.1H NMR (400 MHz, DMSO-d6) δ 6.56 (d, J=2.4 Hz, 1H), 7.43-7.52 (m 2H), 7.78 (s, 1H), 11.57 (brs, 1H).

[1] Patent: WO2017/20010, 2017, A1. Location in patent: Paragraph 0211