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

HRID 408800Notes

Reaction equation

HRID 408800 reaction equation
[CH2:1]([C:3]1[C:11](C(O)=O)=[C:6]2[CH:7]=[CH:8][CH:9]=[CH:10][N:5]2[N:4]=1)[CH3:2].S(=O)(=O)(O)O.C(OCC)(=O)C.C(=O)(O)[O-].[Na+]>O>[CH2:1]([C:3]1[CH:11]=[C:6]2[CH:7]=[CH:8][CH:9]=[CH:10][N:5]2[N:4]=1)[CH3:2]

Participants

6

Reactant 4

HCID 1118Sulfuric AcidHCID 8857Ethyl AcetateHCID 516892Sodium BicarbonateHCID 583793202-Ethylpyrazolo[1,5-a]pyridine-3-carboxylic acid

Product 1

HCID 161162612-Ethylpyrazolo[1,5-a]pyridineYield 82%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Conditions

Temperature
70 °C

Procedure

2-Ethylpyrazolo[1,5-a]pyridine-3-carboxylic acid (4.1 g, 22 mmol) was stirred in water (100 mL) and sulfuric acid (2.5 mL) was added. The mixture was heated at 70° C. for 2 h and cooled to 20° C. The mixture was poured into ethyl acetate and neutralized with saturated sodium bicarbonate. The extracts were separated and the aqueous layer was extracted with ethyl acetate. The combined extracts were dried (sodium sulfate) and evaporated to give the desired compound (2.6 g, 82%). LCMS for C9H11N2 (M+H)+: m/z=147.1. 1H NMR (300 MHz, DMSO-d6): δ 8.52 (m, 1H), 7.57 (m, 1H), 7.11 (m, 1H), 6.75 (m, 1H), 6.38 (s, 1H), 2.73 (m, 2H), 1.22 (m, 3H).

Workup

  1. temperaturecooled to 20° C
  2. customThe extracts were separated
  3. extractionthe aqueous layer was extracted with ethyl acetate
  4. dry with materialThe combined extracts were dried (sodium sulfate)
  5. customevaporated

Sources & evidence

ORD record
ord-dff0416bf98646839691f01d002b0f15
Source dataset
uspto-grants-2014_06
Patent number
US08759359B2

Reaction notes

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