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

HRID 921003Notes

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-ccbdc0472c1a41ec8fb9c907f86a65f7
Source dataset: uspto-grants-2016_03
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09273069B2

Reaction notes

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