Nitric Acid → 7-Bromo-2-ethyl-3-nitropyrazolo[1,5-a]pyridine

HRID 347875

Reaction equation

HRID 347875 reaction equation
[N+:1]([O-:4])(O)=[O:2].[Br:5][C:6]1[N:11]2[N:12]=[C:13]([CH2:15][CH3:16])[CH:14]=[C:10]2[CH:9]=[CH:8][CH:7]=1>S(=O)(=O)(O)O>[Br:5][C:6]1[N:11]2[N:12]=[C:13]([CH2:15][CH3:16])[C:14]([N+:1]([O-:4])=[O:2])=[C:10]2[CH:9]=[CH:8][CH:7]=1

Participants

4

Reactant 2

HCID 944Nitric AcidHCID 219845107-Bromo-2-ethylpyrazolo[1,5-a]pyridine

Product 1

HCID 219844817-Bromo-2-ethyl-3-nitropyrazolo[1,5-a]pyridineYield 31%

Reagents, catalysts & solvents 1

HCID 1118Sulfuric AcidSolvent

Conditions

Temperature
70 °C

Procedure

Fuming nitric acid (1.7 mL) was added dropwise to a solution of 7-bromo-2-ethylpyrazolo[1,5-a]pyridine (6.9 g, 34.2 mmol) in concentrated sulfuric acid (13.8 mL) at an internal temperature of below 30° C. while cooling with ice. After stirring the reaction mixture for 30 minutes, it was added to ice water (138 mL) and the precipitate was filtered out. The obtained precipitate was added ethyl acetate (226 mL) and methanol (38 mL), and the mixture was heated to 70° C., and then the precipitate was collected by filtration while cooling with ice. The solvent of the obtained filtrate was evaporated under reduced pressure, and the concentrated residue was recrystallized from heptane-ethyl acetate (1:1) to afford 2.4 g of the title compound as light brown crystals (31% yield).

Workup

  1. temperaturewhile cooling with ice
  2. filtrationthe precipitate was filtered out
  3. additionThe obtained precipitate was added ethyl acetate (226 mL) and methanol (38 mL)
  4. filtrationthe precipitate was collected by filtration
  5. temperaturewhile cooling with ice
  6. customThe solvent of the obtained filtrate was evaporated under reduced pressure
  7. customthe concentrated residue was recrystallized from heptane-ethyl acetate (1:1)

Sources & evidence

ORD record
ord-8b5b93c95e944199a78f70e5b9b2c00b
Source dataset
uspto-grants-2007_02
Patent number
US07176216B2

Linked notes

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