Phosphorus oxybromide → 4-Bromo-2-(2,6-dichloro-4-vinylphenyl)-7-fluoro-2H-pyrazolo[4,3-c]pyridine

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Reaction Conditions

Reaction Steps

To a suspension of 2-(2,6-dichloro-4-vinylphenyl)-7-fluoro-2H-pyrazolo[4,3-c]pyridine 5 oxide (1.0 g, 3.1 mmol) in DCM (15 mL) under an atmosphere of nitrogen at 0° C., was added phosphorus oxybromide (2.6 g, 9.0 mmol). The reaction mixture was stirred at 0° C. for 1 hour and then allowed to reach room temperature over 30 minutes. The resultant mixture was quenched with saturated aqueous sodium hydrogen carbonate solution and diluted with DCM. The layers were separated and the organic layer was washed with brine, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel flash chromatography (20% ethyl acetate in cyclohexane) to afford the title compound as a white solid (304 mg, 25% yield). 1H NMR (400 MHz, DMSO-d6): δ 9.41 (d, J=2.5 Hz, 1H), 8.19 (d, J=3.3 Hz, 1H), 7.99 (s, 2H), 6.85 (dd, J=17.6, 11.0 Hz, 1H), 6.25 (d, J=17.6 Hz, 1H), 5.60 (d, J=11.0 Hz, 1H).

Provenance & Evidence