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

HRID 329178Notes

Reaction equation

HRID 329178 reaction equation
[CH2:1]([O:3][C:4]([C:6]1[C:7](O)=[C:8]2[C:14]([CH3:15])=[N:13][N:12]([CH2:16][CH3:17])[C:9]2=[N:10][CH:11]=1)=[O:5])[CH3:2].P(Cl)(Cl)([Cl:21])=O>>[CH2:1]([O:3][C:4]([C:6]1[C:7]([Cl:21])=[C:8]2[C:14]([CH3:15])=[N:13][N:12]([CH2:16][CH3:17])[C:9]2=[N:10][CH:11]=1)=[O:5])[CH3:2]

Participants

3

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 1784695811-ethyl-4-hydroxy-3-methyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester

Product 1

HCID 1473447ethyl 4-chloro-1-ethyl-3-methyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylate

Procedure

A mixture of 24.9 g. 1-ethyl-4-hydroxy-3-methyl-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. 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 (25 g., m.p. 70°-74°). The 4-chloro-1-ethyl-3-methyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester is recrystallized from cyclohexane, yield 22.8 g. (85%), m.p. 78°-79°.

Workup

  1. additionA mixture of 24.9 g
  2. customThe 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 (25 g., m.p. 70°-74°)
  7. customThe 4-chloro-1-ethyl-3-methyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester is recrystallized from cyclohexane, yield 22.8 g

Sources & evidence

ORD record
ord-16f5ccc875be4bfa9d20aa778de307a5
Source dataset
uspto-grants-1977_04
Patent number
US04020072

Reaction notes

Loading…