271-34-1

24424-99-5

148760-75-2

Step A: Preparation of tert-butyl 1H-pyrrolo[3,2-c]pyridine-1-carboxylate: To a stirred mixture of 5-azaindole (2.3 g, 20 mmol) and 4-dimethylaminopyridine (2.4 g, 20 mmol) in acetonitrile (20 mL) was added di-tert-butyl dicarbonate (3.9 g, 18 mmol). The reaction mixture was stirred at room temperature for 18 hours. Upon completion of the reaction, the mixture was concentrated under reduced pressure and subsequently purified by Biotage Flash 40S column chromatography using 1:1 ethyl acetate/hexane as eluent. The target product 1H-pyrrolo[3,2-c]pyridine-1-carboxylic acid tert-butyl ester was obtained as a colorless oil (4.0 g, 101% yield).