Acetic Anhydride → 1-Methylethyl 5-(phenylmethoxy)-1H-indazole-3-carboxylate

HRID 1604630Notes

Reaction equation

C([O-])(=O)C.[K+].[NH2:6][C:7]1[CH:12]=[CH:11][C:10]([O:13][CH2:14][C:15]2[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=2)=[CH:9][C:8]=1[CH2:21][C:22]([O:24][CH:25]([CH3:27])[CH3:26])=[O:23].C(OC(=O)C)(=O)C.C(O[N:41]=O)CC(C)C>C1C=CC=CC=1>[CH2:14]([O:13][C:10]1[CH:9]=[C:8]2[C:7](=[CH:12][CH:11]=1)[NH:6][N:41]=[C:21]2[C:22]([O:24][CH:25]([CH3:27])[CH3:26])=[O:23])[C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1

Participants

Conditions

Temperature: 80 °C

Procedure

A mixture of potassium acetate (1.34 g), isopropyl 2-amino-5-benzyloxyphenylacetate (3.9 g) and acetic anhydride (4.0 g) in benzene (40 ml) was stirred at 80° C. After 30 minutes, isopentylnitrite (2.3 g) was added dropwise to the mixture over 15 minutes and then the mixture was stirred at same temperature for 4 hours. After cooling, insoluble mass was filtered off and the filtrate was concentrated under reduced pressure. The residue was dissolved in isopropyl alcohol (30 ml) containing conc. sulphuric acid (0.5 ml) and the mixture was stirred at 80° C. for 3 hours. After cooling to room temperatures the resulting crystals were collected by filtration and washed with isopropyl ether to give isopropyl 5-benzyloxy-1H-indazole-3-carboxylate (2.4 g).

Workup

stirringthe mixture was stirred at same temperature for 4 hours
temperatureAfter cooling
filtrationinsoluble mass was filtered off
concentrationthe filtrate was concentrated under reduced pressure
dissolutionThe residue was dissolved in isopropyl alcohol (30 ml)
additioncontaining conc. sulphuric acid (0.5 ml)
stirringthe mixture was stirred at 80° C. for 3 hours
temperatureAfter cooling to room temperatures the resulting crystals
filtrationwere collected by filtration
washwashed with isopropyl ether

Sources & evidence

ORD record: ord-b5aca1c87310416d8e84518bd59f8223
Source dataset: uspto-grants-1999_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05994378

Reaction notes

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