4649-09-6

271-63-6

64-19-7

4649-09-6

1H-pyrrolo[2,3-b]pyridine (11.80 g, 100 mmol) was suspended in 33% aqueous acetic acid (200 mL) at room temperature, followed by the addition of hexamethylenetetramine (16.8 g, 120 mmol). The reaction mixture was heated to 110-120 °C (oil bath temperature) and stirred continuously at this temperature for 15 hours. Upon completion of the reaction, the mixture was cooled to room temperature, at which point a large amount of solid precipitated. The suspension was poured into a 2 L beaker containing ice and the reaction flask was rinsed with 50 mL of water. Subsequently, saturated sodium bicarbonate solution was slowly added for neutralization. After completion of neutralization, the solid product was collected by filtration and washed with distilled water. The product was dried in air to give 1H-pyrrolo[2,3-b]pyridine-3-carboxaldehyde (9.5 g, 65% yield) as a white solid.EI-HRMS analysis results: m/e calculated value C8H6N2O (M+) 146.0480, measured value 146.0478.