Sulfuric Acid → 2-Isopropylpyrazolo[1,5-a]pyridine

HRID 731736Notes

Reaction equation

HRID 731736 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].S(=O)(=O)(O)O.[OH-].[Na+]>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

5

Reactant 3

HCID 1118Sulfuric AcidHCID 3671IbudilastHCID 14798Sodium Hydroxide

Product 1

HCID 113786582-Isopropylpyrazolo[1,5-a]pyridineYield 81%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent2×

Conditions

Temperature
130 °C

Procedure

1-(2-Isopropyl-pyrazolo[1,5-a]pyridin-3-yl)-2-methyl-propan-1-one (30.0 g, 115 mmole), water (100 ml), and concentrated sulfuric acid (100 ml) were combined and stirred at 130° C. for 18 hours. The mixture was cooled to room temperature and poured into a solution of ice (400 g) and water (200 ml). The solution was neutralized with sodium hydroxide solution and extracted with chloroform. The organic layer was dried over sodium sulfate, filtered, and concentrated in vacuo. The oil was purified by vacuum distillation to give 14.9 g (81%) of 2-isopropyl-pyrazolo[1,5-a]pyridine. 1H-NMR (250 MHz, DMSO-d6) δ 8.37 (d, J=7.3 Hz, 1H), 7.41 (d, J=9.0 Hz, 1H), 7.00 (t, J=7.3 Hz, 1H), 6.66 (t, J=7.5 Hz, 1H), 6.28 (s, 1H), 3.16 (sept, J=7.0 Hz, 1H), 1.35 (d, J=6.8 Hz, 6H).

Workup

  1. temperatureThe mixture was cooled to room temperature
  2. extractionextracted with chloroform
  3. dry with materialThe organic layer was dried over sodium sulfate
  4. filtrationfiltered
  5. concentrationconcentrated in vacuo
  6. distillationThe oil was purified by vacuum distillation

Sources & evidence

ORD record
ord-6d3c54f4cac24ea5b5e826d9b1e12bdf
Source dataset
uspto-grants-2009_09
Patent number
US07585875B2

Reaction notes

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