Hydrochloric Acid → 2,3-dihydro-6-(4-fluorophenyl)-7-(pyridin-4-yl)-1H-imidazo[1,2-b]pyrazole

HRID 54941Notes

Reaction equation

[F:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[C:9]([C:17]3[CH:22]=[CH:21][N:20]=[CH:19][CH:18]=3)=[C:10]3[NH:15][C:14](=O)[CH2:13][N:11]3[N:12]=2)=[CH:4][CH:3]=1.B#B.Cl.C(=O)(O)[O-].[Na+]>O1CCCC1>[F:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[C:9]([C:17]3[CH:22]=[CH:21][N:20]=[CH:19][CH:18]=3)=[C:10]3[NH:15][CH2:14][CH2:13][N:11]3[N:12]=2)=[CH:4][CH:3]=1

Participants

Conditions

Temperature: 60 °C

Procedure

A mixture of 2,3-dihydro-6-(4-fluorophenyl)-2-oxo-7-(pyridin-4-yl)-1H-imidazo[1,2-b]pyrazole (50 mg) and diborane (0.34 mmol) in anhydrous tetrahydrofuran (5 ml) was refluxed under nitrogen atmosphere for 5 hours. After cooling of the reaction mixture, to the mixture was added 1N-hydrochloric acid (2 ml). The mixture was stirred at 60° C. for 30 minutes, cooled and neutralized with an aqueous saturated sodium bicarbonate solution. The separated oil was extracted with dichloromethane and the extract was washed with brine, dried and concentrated in vacuo. The residue was purified by thin layer chromatography on silica gel and the obtained crude solid was recrystallized from a mixture of diisopropyl ether and dichloromethane to yield 2,3-dihydro-6-(4-fluorophenyl)-7-(pyridin-4-yl)-1H-imidazo[1,2-b]pyrazole (14 mg).

Workup

temperaturewas refluxed under nitrogen atmosphere for 5 hours
temperatureAfter cooling of the reaction mixture, to the mixture
temperaturecooled
extractionThe separated oil was extracted with dichloromethane
washthe extract was washed with brine
customdried
concentrationconcentrated in vacuo
customThe residue was purified by thin layer chromatography on silica gel
customthe obtained crude solid
customwas recrystallized from a mixture of diisopropyl ether and dichloromethane

Sources & evidence

ORD record: ord-eccec653287941c79b8eeddbf9876828
Source dataset: uspto-grants-1997_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05624931

Reaction notes

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