757978-33-9

64-19-7

183208-35-7

757978-33-9

(a) Step 1: Glacial acetic acid (0.2 mL), water (0.4 mL) and hexamethylenetetetramine (0.087 g, 0.62 mmol) were added sequentially to 5-bromo-7-azaindole (0.087 g, 0.44 mmol), and the reaction was carried out in a sealed tube with stirring at 120°C overnight. Upon completion of the reaction, water was added to the mixture and the precipitated solid was collected by filtration to afford 5-bromo-1H-pyrrolo[2,3-b]pyridine-3-carbaldehyde (0.061 g, 62% yield). The product was characterized by 1H NMR (300 MHz, CDCl3): δ 8.46 (d, J = 2.2 Hz, 1H), 8.53 (d, J = 2.2 Hz, 1H), 8.54 (s, 1H), 9.93 (s, 1H).