Phosphorus oxychloride → ethyl 4-chloro-1-ethyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylate

HRID 596759Notes

Reaction equation

HRID 596759 reaction equation
[CH2:1]([O:3][C:4]([C:6]1[C:7](O)=[C:8]2[CH:14]=[N:13][N:12]([CH2:15][CH3:16])[C:9]2=[N:10][CH:11]=1)=[O:5])[CH3:2].P(Cl)(Cl)([Cl:20])=O>>[CH2:1]([O:3][C:4]([C:6]1[C:7]([Cl:20])=[C:8]2[CH:14]=[N:13][N:12]([CH2:15][CH3:16])[C:9]2=[N:10][CH:11]=1)=[O:5])[CH3:2]

Participants

3

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 178469631HCID 178469631, compound

Product 1

HCID 10491120ethyl 4-chloro-1-ethyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylate

Procedure

A mixture of 23.5 g. of 1-ethyl-4-hydroxy-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester (0.1 mol.) and 150 ml. of phosphorus oxychloride is refluxed for 4 hours. Subsequently, the excess phosphorus oxychloride is removed by means of vacuum distillation. As soon as the phosphorus oxychloride has been removed, the oily residue solidifies on cooling. It is treated with water and filtered under suction (24.5 g.), m.p. 55°-60°. The 4-chloro-1-ethyl-1H-pyrazolo[3,4-b]-pyridine-5-carboxylic acid ethyl ester is recrystallized from N-hexane (22.5 g. = 87%), m.p. 62°.

Workup

  1. additionA mixture of 23.5 g
  2. customSubsequently, the excess phosphorus oxychloride is removed by means of vacuum distillation
  3. customAs soon as the phosphorus oxychloride has been removed
  4. temperatureon cooling
  5. additionIt is treated with water
  6. filtrationfiltered under suction (24.5 g.), m.p. 55°-60°
  7. customThe 4-chloro-1-ethyl-1H-pyrazolo[3,4-b]-pyridine-5-carboxylic acid ethyl ester is recrystallized from N-hexane (22.5 g. = 87%), m.p. 62°

Sources & evidence

ORD record
ord-34195a07e2284809843f04192e9afb75
Source dataset
uspto-grants-1977_03
Patent number
US04012373

Reaction notes

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