3-bromo-1H-pyrrolo[3,2-b]pyridine

272-49-1

23688-47-3

Example 3 Synthesis of 3-bromo-4-azaindole: 0.9707 g (8.21 mmol) of 4-azaindole was dissolved in 50 mL of acetonitrile in a 250 mL three-necked, round-bottomed flask equipped with a magnetic stirrer, a thermocouple, a nitrogen inlet, and an ice bath cooling device. At 170 °C, 5.5187 g (24.7 mmol, 3 eq.) of solid CuBr2 was added to the flask in batches over 10 min. The reaction mixture formed a green suspension and was stirred at room temperature until the TLC assay showed the disappearance of the raw material (about 1-2 hours). The reaction mixture was cooled to 10 °C and quenched by slowly adding 60 mL of a methanol solution of 7N ammonia. The resulting blue solution was concentrated by rotary evaporation at room temperature and the residue was extracted with ethyl acetate (3 x 80 mL). The organic phases were combined, dried with Na2SO4, filtered and concentrated by rotary evaporation to give 1.4 g of an off-white solid. The solid was suspended in 100 mL of hexane, filtered and dried in vacuum to give 1.225 g (76% yield) of 3-bromo-4-azaindole as a white solid.