Phosphorus oxychloride → ETHYL6-CHLORO-1H-PYRAZOLO[3,4-B]PYRIDINE-4-CARBOXYLATE

HRID 82021Notes

Reaction equation

HRID 82021 reaction equation
[CH2:1]([O:3][C:4]([C:6]1[C:7]2[CH:15]=[N:14][NH:13][C:8]=2[N:9]=[C:10](O)[CH:11]=1)=[O:5])[CH3:2].P(Cl)(Cl)([Cl:18])=O>>[CH2:1]([O:3][C:4]([C:6]1[C:7]2[CH:15]=[N:14][NH:13][C:8]=2[N:9]=[C:10]([Cl:18])[CH:11]=1)=[O:5])[CH3:2]

Participants

3

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 178469358ethyl 6-oxo-1,2-dihydropyrazolo[3,4-b]pyridine-4-carboxylate

Product 1

HCID 86678157ETHYL6-CHLORO-1H-PYRAZOLO[3,4-B]PYRIDINE-4-CARBOXYLATEYield 21%

Conditions

Temperature
110 °C

Procedure

A mixture of 6-hydroxy-1H-pyrazolo[3,4-b]pyridine-4-carboxylic acid ethyl ester (116.4 g, 0.562 mol) and phosphorus oxychloride (500 mL) was heated at 110° C. for 6 hours then cooled to room temperature before being evaporated under reduced pressure. The residue was taken up in EtOAc and the precipitate filtered. The filtrate was neutralized using triethylamine (500 mL) and the resulting salt filtered. The filtrate was concentrated under vacuum and the residue subjected to silica gel column chromatography using a 9/1 mixture of toluene/EtOAc to afford the title compound as a yellow solid (26.3 g, 21%).

Workup

  1. temperaturethen cooled to room temperature
  2. custombefore being evaporated under reduced pressure
  3. filtrationthe precipitate filtered
  4. filtrationthe resulting salt filtered
  5. concentrationThe filtrate was concentrated under vacuum
  6. additiona 9/1 mixture of toluene/EtOAc

Sources & evidence

ORD record
ord-2e142686eb7b43f5b7fabf52ef3aa8ed
Source dataset
uspto-grants-2014_09
Patent number
US08846712B2

Reaction notes

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