Phosphorus oxybromide → 4-Bromo-2-(2-chloro-6-fluorophenyl)-2H-pyrazolo[4,3-c]pyridine

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Reaction Conditions

Reaction Steps

To a suspension of 2-(2-chloro-6-fluorophenyl)-2H-pyrazolo[4,3-c]pyridine 5-oxide (740 mg, 2.8 mmol) in DCE (18 mL) at 0° C. was added phosphorus oxybromide (2.4 g, 8.4 mmol). The reaction mixture was stirred at 0° C. for 15 minutes, warmed to room temperature, and stirred for an additional 4.5 h. The resultant mixture was diluted with DCM, washed with sodium carbonate (sat. aq.) and then with brine. The organic phase was dried over anhydrous magnesium sulphate and concentrated under reduced pressure. The residue was purified by silica gel flash chromatography (0-30% ethyl acetate in cyclohexane) to afford the title compound as a white solid (230 mg, 25% yield). LCMS (Method C): RT=3.44 min, m/z: 327 [M+H+].

Provenance & Evidence