6-bromo-5-chloro-indole

16588-26-4

1826-67-1

1191028-50-8

1191028-48-4

A tetrahydrofuran (THF) solution of 1.0 M vinylmagnesium bromide (0.13 L, 130 mmol) was slowly added dropwise to a 140 mL THF solution of 10 g (43 mmol) of 3-bromo-4-chloronitrobenzene at -40 °C. After the dropwise addition was completed, the reaction mixture was continued to be stirred at -40 °C for 1 hour. Subsequently, the reaction mixture was slowly warmed to room temperature and extracted with ethyl acetate (EtOAc). The organic phases were combined, washed with saturated brine, dried over anhydrous magnesium sulfate (MgSO), filtered and concentrated. The crude product was purified twice by column chromatography (eluent: hexane solution of 33% ethyl acetate) to give 0.95 g (9.7% yield) of 4-bromo-5-chloro-1H-indole and 0.77 g (7.9% yield) of 6-bromo-5-chloro-1H-indole, respectively. Each indole product was dissolved in acetonitrile (MeCN) and the reaction was carried out by adding 1.1 equiv. of di-tert-butyl dicarbonate (BocO) and 0.2 equiv. of 4-dimethylaminopyridine (DMAP). Upon completion of the reaction, the mixture was concentrated and the residue was purified by column chromatography (eluent: 10% hexane solution of ethyl acetate) to give 1-011 (32% yield) and 1-012 (48% yield).