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

HRID 626732Notes

Reaction equation

[Br:1][C:2]1[C:3]2[C:4](=[CH:9][N:10]([C:12]3[C:17]([Cl:18])=[CH:16][CH:15]=[CH:14][C:13]=3[Cl:19])[N:11]=2)[CH:5]=[N+:6]([O-])[CH:7]=1.P(Br)(Br)([Br:22])=O>ClCCCl>[Br:22][C:5]1[C:4]2=[CH:9][N:10]([C:12]3[C:17]([Cl:18])=[CH:16][CH:15]=[CH:14][C:13]=3[Cl:19])[N:11]=[C:3]2[C:2]([Br:1])=[CH:7][N:6]=1

Participants

Conditions

Temperature: 0 °C

Procedure

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+].

Workup

temperatureTo a cooled
temperaturewarmed to room temperature
stirringstirred for a further 2.25 hours
customThe reaction mixture was partitioned between DCM and sodium carbonate (sat. aq.)
washThe organic layer was washed with brine
dry with materialdried over anhydrous sodium sulfate
concentrationconcentrated under reduced pressure
customThe residue was purified by silica gel flash chromatography (0-20% ethyl acetate in cyclohexane)

Sources & evidence

ORD record: ord-a027bc24e37d4b9bb1ead1208a062348
Source dataset: uspto-grants-2016_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09309240B2

Reaction notes

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