24424-99-5

23612-36-4

192189-16-5

3.5601 g (18.06 mmol) of 3-bromo-1H-pyrrolo[3,2-c]pyridine and 0.4651 g (3.8 mmol, 21 mol%) of dimethylaminopyridine (DMAP) were dissolved in 80 mL of tetrahydrofuran (THF), and the solution was transferred to a 250 mL three-necked round-bottomed flask. The flask was equipped with a magnetic stirrer, thermocouple, nitrogen inlet and outlet and an ice bath cooling device. At 17 °C, 4.7769 g (21.88 mmol, 1.2 eq.) of di-tert-butyl dicarbonate (Boc2O) was slowly added to the reaction system, and the reaction mixture was continuously stirred until 3-bromo-1H-pyrrolo[3,2-c]pyridine was completely disappeared, and the progress of the reaction was monitored by thin-layer chromatography (TLC) (usually overnight with stirring at room temperature). Upon completion of the reaction, the resulting yellow solution was concentrated on a rotary evaporator and subsequently washed with 100 mL of saturated sodium bicarbonate solution and extracted with dichloromethane (3 x 80 mL). The organic phases were combined, dried over anhydrous sodium sulfate (Na2SO4), filtered and concentrated again on a rotary evaporator to give 6.57 g of orange solid crude product. The crude product was purified by a CombiFlash fast chromatography system using hexane/ethyl acetate as eluent, resulting in 5.25 g (97% yield) of 3-bromo-1H-pyrrolo[3,2-c]pyridine-1-carboxylic acid tert-butyl ester as a white solid.