Phosphorus oxybromide → 4,7-Dibromo-2-(2,6-dichlorophenyl)-2H-pyrazolo[4,3-c]pyridine

Participants

Reaction Conditions

Reaction Steps

To a cooled (0° C.) suspension of 7-bromo-2-(2,6-dichlorophenyl)-2H-pyrazolo[4,3-c]pyridine-5-oxide (1.7 g, 4.7 mmol) in DCE (30 mL) was added phosphorus oxybromide (4.0 g, 14.1 mmol). The reaction mixture was stirred at 0° C. for 15 minutes, warmed to room temperature, and stirred for a further 2.25 hours. The reaction mixture was partitioned between DCM and sodium carbonate (sat. aq.). The organic layer was washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel flash chromatography (0-20% ethyl acetate in cyclohexane) to afford the title compound as a white solid (1.07 g, 54% yield). LCMS (Method D): RT=3.93 min, m/z: 422 [M+H+].

Provenance & Evidence