Ibudilast → 2-Isopropylpyrazolo[1,5-a]pyridine

HRID 436802

Reaction equation

HRID 436802 reaction equation
[CH:1]([C:4]1[C:12](C(=O)C(C)C)=[C:7]2[CH:8]=[CH:9][CH:10]=[CH:11][N:6]2[N:5]=1)([CH3:3])[CH3:2].[OH-].[Na+]>S(=O)(=O)(O)O>[CH:1]([C:4]1[CH:12]=[C:7]2[CH:8]=[CH:9][CH:10]=[CH:11][N:6]2[N:5]=1)([CH3:3])[CH3:2]

Participants

4

Reactant 2

HCID 3671IbudilastHCID 14798Sodium Hydroxide

Product 1

HCID 113786582-Isopropylpyrazolo[1,5-a]pyridine

Reagents, catalysts & solvents 1

HCID 1118Sulfuric AcidSolvent

Conditions

Temperature
140 °C

Procedure

A mixture of 30g (0.13 mole) of 2-isopropyl-3-isobutyrylpyrazolo[1,5-a]pyridine and 200 ml of 50% sulfuric acid (v/v) solution was heated at 140° C for 10 hours. After cooling, the mixture was added to 400g of ice-water. The solution was neutralized with sodium hydroxide solution and extracted with chloroform. The chloroform solution was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was distilled to give 8.5g (5.3 × 10-2 mole) of colorless oily product, bp 127.5°-129.5° C (17 mmHg).

Workup

  1. temperatureAfter cooling
  2. extractionextracted with chloroform
  3. dry with materialThe chloroform solution was dried over anhydrous sodium sulfate
  4. concentrationconcentrated under reduced pressure
  5. distillationThe residue was distilled

Sources & evidence

ORD record
ord-aff47afc56f346a5aa54cc804b107b9b
Source dataset
uspto-grants-1977_06
Patent number
US04028370

Linked notes

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