130473-27-7

130473-26-6

130473-27-7

1H-pyrrolo[2,3-c]pyridine-5-carboxaldehyde (500 mg, 3.42 mmol) was used as starting material, which was dissolved in 1.5 mL of formic acid. The reaction solution was cooled in an ice bath, and 30% aqueous hydrogen peroxide solution (722 μL, 6.8 mmol) was added slowly and dropwise, keeping the reaction system stirred in an ice bath for 1 h. The reaction system was then left to stand at 5 °C overnight. Upon completion of the reaction, the reaction solution was diluted with deionized water, and the resulting solid was collected, washed with deionized water and dried to give 522 mg of an off-white solid. The formate was dissolved in 7 mL of deionized water, 3 mL of 2N sodium hydroxide solution was added, and the pH was adjusted with 5% aqueous hydrochloric acid to 3. The precipitate precipitated was collected and dried to give 1H-pyrrolo[2,3-c]pyridine-5-carboxylic acid (67% yield). High resolution mass spectrometry (FAB) analysis resulted in a theoretically calculated value of 163.0508 for C8H6N2O2 + H and a measured value of 163.0507 (M + H). In Example 23(i), the target product can be obtained by coupling exo-[2.2.1]-3-amine or endo-[2.2.1]-3-amine with 1H-pyrrolo[2,3-c]pyridine-5-carboxylic acid.