Hydrochloric Acid → 2,3-Dihydro-5-nitro-1H-indazol-3-one

HRID 535687Notes

Reaction equation

O.[NH2:2][NH2:3].Cl[C:5]1[CH:13]=[CH:12][C:11]([N+:14]([O-:16])=[O:15])=[CH:10][C:6]=1[C:7](O)=[O:8].Cl>C(O)C>[N+:14]([C:11]1[CH:10]=[C:6]2[C:5](=[CH:13][CH:12]=1)[NH:3][NH:2][C:7]2=[O:8])([O-:16])=[O:15]

Participants

Conditions

Temperature: 0 °C

Procedure

Hydrazine hydrate (4 mL, 124 mmol) was added to a solution of 2-chloro-5-nitro benzoic acid (5 g, 24.8 mmol) in absolute ethanol (30 mL), and the resulting mixture was refluxed for 16 h. The reaction mixture was concentrated under reduced pressure. Residue was trituated with methanol to give 6.5 g of crude intermediate. 2N aq. HCl (40 mL) was added to the crude product, and the mixture was refluxed for 8 h. Reaction mixture was cooled to 0° C., solids were collected via filtration, washed with cold water and dried under vacuum. Residue was purified by flash chromatography using 1% methanol in chloroform as eluent to afford title compound (2 g, 27%) as a solid. 1H NMR (400 MHz, DMSO-d6): δ 12.4 (bs, 1H), 11.3 (bs, 1H), 8.67 (s, 1H), 8.12 (dd, J1=2.1 Hz, J2=9.0 Hz, 1H), 7.5 (d, J=9.0 Hz, 1H); ESI-MS m/z: 179 (M+H)+.

Workup

temperaturethe resulting mixture was refluxed for 16 h
concentrationThe reaction mixture was concentrated under reduced pressure
customto give 6.5 g of crude intermediate
temperaturethe mixture was refluxed for 8 h
customReaction mixture
filtrationsolids were collected via filtration
washwashed with cold water
customdried under vacuum
customResidue was purified by flash chromatography

Sources & evidence

ORD record: ord-298b6bbbe53c46f8b00a618322599531
Source dataset: uspto-grants-2014_10
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08859536B2

Reaction notes

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