1032943-43-3

1227573-02-5

1032943-43-3

General procedure for the synthesis of 4-bromo-1H-pyrazolo[3,4-c]pyridine from 3-bromo-5-fluoroisonicotinaldehyde: Hydrogen peroxide (H2O2, 25.0 mL) was added to a solution of 3-bromo-5-fluoroisonicotinaldehyde (5.0 g, 24.5 mmol, 1.0 eq.) in 1,2-dimethoxyethane (DME, 25.0 mL), and the reaction mixture was 110 °C overnight. Upon completion of the reaction, the solvent was removed by concentration under reduced pressure. The resulting residue was diluted with water, extracted with ethyl acetate (EA, 100.0 mL × 3), and the organic phases were combined and washed with saturated brine, dried over anhydrous sodium sulfate (Na2SO4), and concentrated again under reduced pressure. The obtained residue was purified by silica gel column chromatography (eluent ratio: petroleum ether:ethyl acetate = 2:1), and the target product, 4-bromo-1H-pyrazolo[3,4-c]pyridine (1.5 g, 31.3% yield), was obtained as a white solid. m/z of LC-MS (M + H+) was calculated at 198.1, and the measured value was 198.2.