Methanol → methyl 1H-indazole-3-carboxylate

HRID 1666058Notes

Reaction equation

HRID 1666058 reaction equation
[NH:1]1[C:9]2[C:4](=[CH:5][CH:6]=[CH:7][CH:8]=2)[C:3]([C:10]([OH:12])=[O:11])=[N:2]1.OS(O)(=O)=O.[CH3:18]O>O>[CH3:18][O:11][C:10]([C:3]1[C:4]2[C:9](=[CH:8][CH:7]=[CH:6][CH:5]=2)[NH:1][N:2]=1)=[O:12]

Participants

5

Reactant 3

HCID 887MethanolHCID 1118Sulfuric AcidHCID 78250Indazole-3-carboxylic acid

Product 1

HCID 657476methyl 1H-indazole-3-carboxylate

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Conditions

Temperature
80 °C

Procedure

To indazole-3-carboxylic acid (40 g, 247 mmol) suspended in methanol (700 mL) was added concentrated H2SO4 (10 mL) slowly while stirring the mixture. The mixture was stirred and refluxed at 80° C. for 24 h. The mixture was cooled, filtered, and concentrated under reduced pressure to afford a pale yellow solid. The solid was suspended in water (700 mL), crushed to fine powder, collected by filtration, and rinsed with water (˜400 mL). The product was suspended in toluene, and evaporated to dryness under reduced pressure, affording indazole-3-carboxylic acid methyl ester as a pale yellow solid (45 g, >95% pure). (m/z): [M+H]+ calcd for C9H8N2O2 177.07; found, 177.0. 1H-NMR (CD3OD, 300 MHz): δ (ppm) 8.0 (1H, d), 7.5 (1H, d), 7.4 (1H, t), 7.2 (1H, t), 3.9 (3H, s).

Workup

  1. stirringThe mixture was stirred
  2. temperatureThe mixture was cooled
  3. filtrationfiltered
  4. concentrationconcentrated under reduced pressure
  5. customto afford a pale yellow solid
  6. customcrushed to fine powder
  7. filtrationcollected by filtration
  8. washrinsed with water (˜400 mL)
  9. customevaporated to dryness under reduced pressure

Sources & evidence

ORD record
ord-17fa03230e554880a84de9234246cf12
Source dataset
uspto-grants-2011_10
Patent number
US08044045B2

Reaction notes

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