Ethanol → 7-Bromo-2-ethylpyrazolo[1,5-a]pyridine-3-amine

HRID 2253362Notes

Reaction equation

HRID 2253362 reaction equation
[Br:1][C:2]1[N:7]2[N:8]=[C:9]([CH2:14][CH3:15])[C:10]([N+:11]([O-])=O)=[C:6]2[CH:5]=[CH:4][CH:3]=1.C(O)C.O>[Zn].C(O)(=O)C>[Br:1][C:2]1[N:7]2[N:8]=[C:9]([CH2:14][CH3:15])[C:10]([NH2:11])=[C:6]2[CH:5]=[CH:4][CH:3]=1

Participants

6

Reactant 3

HCID 702EthanolHCID 962WaterHCID 219844817-Bromo-2-ethyl-3-nitropyrazolo[1,5-a]pyridine

Product 1

HCID 210841117-Bromo-2-ethylpyrazolo[1,5-a]pyridine-3-amineYield 73.3%

Reagents, catalysts & solvents 2

HCID 23994ZincCatalystHCID 176Acetic AcidSolvent

Conditions

Temperature
65 °C

Procedure

To a suspension of 7-bromo-2-ethyl-3-nitropyrazolo[1,5-a]pyridine (1.78 g) in a mixed solution of ethanol (100 mL), water (50 mL) and acetic acid (10 mL) was added zinc powder (1.78 g) at room temperature and the reaction mixture was stirred for 1 hour at 65° C. The reaction mixture was filtered through celite to remove insoluble residue and the filtrate was evaporated under reduced pressure. Water was added to the obtained residue and extraction was performed with ethyl acetate, and after washing the organic extract with water, saturated aqueous sodium bicarbonate and brine, the organic extract was dried over anhydrous magnesium sulfate and filtered, and the solvent was evaporated under reduced pressure. The obtained residue was purified by silica gel column chromatography (60 g) and the title compound (1.16 g) was obtained as a dark green oil from the ethyl acetate:n-hexane (4:1) fraction.

Workup

  1. filtrationThe reaction mixture was filtered through celite
  2. customto remove insoluble residue
  3. customthe filtrate was evaporated under reduced pressure
  4. additionWater was added to the obtained residue and extraction
  5. washafter washing the
  6. extractionorganic extract with water, saturated aqueous sodium bicarbonate and brine
  7. extractionthe organic extract
  8. dry with materialwas dried over anhydrous magnesium sulfate
  9. filtrationfiltered
  10. customthe solvent was evaporated under reduced pressure
  11. customThe obtained residue was purified by silica gel column chromatography (60 g)

Sources & evidence

ORD record
ord-dc12276073cd482ebf2d83c5a53e4395
Source dataset
uspto-grants-2008_01
Patent number
US07323569B2

Reaction notes

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