Hydrochloric Acid → 1-(6-Chloro-3-pyridazinyl)-5-(2-pyridyl)pyrazole-3-carboxylic acid ethyl ester

HRID 1437263Notes

Reaction equation

HRID 1437263 reaction equation
[Cl:1][C:2]1[N:3]=[N:4][C:5]([NH:8][NH2:9])=[CH:6][CH:7]=1.[CH2:10]([O:12][C:13](=[O:25])[C:14](=O)[CH2:15][C:16]([C:18]1[CH:23]=[CH:22][CH:21]=[CH:20][N:19]=1)=O)[CH3:11].Cl>C(O)C>[CH2:10]([O:12][C:13]([C:14]1[CH:15]=[C:16]([C:18]2[CH:23]=[CH:22][CH:21]=[CH:20][N:19]=2)[N:8]([C:5]2[N:4]=[N:3][C:2]([Cl:1])=[CH:7][CH:6]=2)[N:9]=1)=[O:25])[CH3:11]

Participants

5

Reactant 3

HCID 313Hydrochloric AcidHCID 1007873-Chloro-6-hydrazinopyridazineHCID 12171345Ethyl 2,4-dioxo-4-(pyridin-2-yl)butanoate

Product 1

HCID 231434631-(6-Chloro-3-pyridazinyl)-5-(2-pyridyl)pyrazole-3-carboxylic acid ethyl ester

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

3-Chloro-6-hydrazinopyridazine (1.59 g) and the 4-(2-pyridyl)-2,4-dioxobutanoic acid ethyl ester (2.45 g) obtained from Referential Example 31 in ethanol (60 mL) was refluxed under heat for 6 hours. To the reaction mixture, concentrated hydrochloric acid (1 mL) was added, and the mixture was refluxed under heat for 1 hour, and then cooled in air. The reaction solvent was removed under reduced pressure, and the residue was partitioned by use of ethyl acetate and saturated aqueous sodium hydrogencarbonate. The organic layer was washed with saturated brine, and then dried over magnesium sulfate anhydrate, followed by filtration. The solvent was removed under reduced pressure, and the residue was purified through silica gel chromatography (ethyl acetate-hexane), to thereby give 1-(6-chloro-3-pyridazinyl)-5-(2-pyridyl)pyrazole-3-carboxylic acid ethyl ester as a solid (1.50 g, 41%).

Workup

  1. temperaturewas refluxed
  2. temperatureunder heat for 6 hours
  3. temperaturethe mixture was refluxed
  4. temperatureunder heat for 1 hour
  5. temperaturecooled in air
  6. customThe reaction solvent was removed under reduced pressure
  7. customthe residue was partitioned by use of ethyl acetate and saturated aqueous sodium hydrogencarbonate
  8. washThe organic layer was washed with saturated brine
  9. dry with materialdried over magnesium sulfate anhydrate
  10. filtrationfollowed by filtration
  11. customThe solvent was removed under reduced pressure
  12. customthe residue was purified through silica gel chromatography (ethyl acetate-hexane)

Sources & evidence

ORD record
ord-8a779a9f46824cfab0fc3fcf272741a1
Source dataset
uspto-grants-2009_11
Patent number
US07622471B2

Reaction notes

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