Ethyl-2,4-dioxohexanoate → Ethyl 1,5-diethylpyrazole-3-carboxylate

HRID 976991Notes

Reaction equation

HRID 976991 reaction equation
O=[C:2]([CH2:8][C:9](=O)[CH2:10][CH3:11])[C:3]([O:5][CH2:6][CH3:7])=[O:4].C(O)(=O)C(O)=O.[CH2:19]([NH:21][NH2:22])[CH3:20]>C(O)(=O)C>[CH2:19]([N:21]1[C:9]([CH2:10][CH3:11])=[CH:8][C:2]([C:3]([O:5][CH2:6][CH3:7])=[O:4])=[N:22]1)[CH3:20]

Participants

4

Reactant 2

HCID 61590Ethyl-2,4-dioxohexanoateHCID 96181Hydrazine, ethyl-, ethanedioate (1:1)

Product 1

HCID 22145420Ethyl 1,5-diethylpyrazole-3-carboxylateYield 84.5%

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent

Procedure

Ethyl 2,4-dioxohexanoate (21.5 g) in glacial acetic acid (125 ml) was cooled in an ice-bath and treated with N-ethylhydrazine oxalate (18.75 g) over 15 minutes. After addition was complete the mixture was stirred for 3 hours at room temperature. The acetic acid was then removed by evaporation in vacuo. The orange oily residue was dissolved in EtOAc and the solution washed repeatedly with saturated aqueous NaHCO3 and once with brine. Following drying over MgSO4 the solvent was evaporated in vacuo to give ethyl 1,5-diethylpyrazole-3-carboxylate as an oil (20.7 g); δ (CDCl3) 1.25-1.45 (9H, 3×3H,t, J 7 Hz), 2.62 (2H, q, J 7 Hz), 4.17 (2H, q, J 7 Hz), 4.38 (2H, q, J 7 Hz) 6.57 (1H, s) ppm.

Workup

  1. additionAfter addition
  2. customThe acetic acid was then removed by evaporation in vacuo
  3. dissolutionThe orange oily residue was dissolved in EtOAc
  4. washthe solution washed repeatedly with saturated aqueous NaHCO3 and once with brine
  5. dry with materialFollowing drying over MgSO4 the solvent
  6. customwas evaporated in vacuo

Sources & evidence

ORD record
ord-7df498660250484aa7e9bc1f25b9162a
Source dataset
uspto-grants-1997_03
Patent number
US05612477

Reaction notes

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