3,4-dihydro-2H-pyran → 5-bromo-1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazolo[3,4-b]pyridine

Participants

Reaction Conditions

Reaction Steps

To a solution of 5-bromo-1H-pyrazolo[3,4-b]pyridine (1.4 g, 7.2 mmol) and dihydropyran (3.3 mL, 36.0 mmol) in tetrahydrofuran (20 mL) was added (±)-camphorsulfonic acid (250 mg) and the reaction mixture was stirred at 65° C. for 16 hours. After cooling to room temperature it was diluted with ethyl acetate (250 mL), washed with saturated aqueous sodium bicarbonate (2×100 mL) and brine (100 mL), dried over sodium sulfate, filtered and concentrated. Gradient column chromatography (10% to 30% ethyl acetate in hexane) provided 5-bromo-1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazolo[3,4-b]pyridine (1.8 g, 90%). MS (EI) for C11H12BrN3O: 283 (MH+).

Provenance & Evidence