Phosphorus oxybromide → ethyl 6-bromo-1H-pyrazolo[3,4-b]pyridine-4-carboxylate

Participants

Reaction Steps

Ethyl 6-hydroxy-1H-pyrazolo[3,4-b]pyridine-4-carboxylate (25 g, 120 mmol) was suspended in acetonitrile (250 mL) and POBr3 (69.56 g, 241.54 mmol) was added to it. The reaction mixture was refluxed for 6 h. On completion of reaction, acetonitrile was removed under reduced pressure and residue neutralized with saturated NaHCO3 solution was added to it. Extraction was carried out using ethyl acetate; the combined organic layers were washed with water, brine and dried over anhydrous Na2SO4; filtered and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to provide the desired intermediate (25 g, 77%).

Provenance & Evidence