Ethyl chloroformate → 5-Carboethoxy-3-(2,5-dimethylpyrrolyl)-1-methylpyrazole

HRID 2291363Notes

Reaction equation

HRID 2291363 reaction equation
[CH3:1][C:2]1[NH:3][C:4]([CH3:13])=[CH:5][C:6]=1[C:7]1[CH:11]=[CH:10][N:9]([CH3:12])[N:8]=1.C([Li])CCC.Cl[C:20]([O:22][CH2:23][CH3:24])=[O:21]>O1CCCC1>[C:20]([C:10]1[N:9]([CH3:12])[N:8]=[C:7]([C:6]2[CH:5]=[C:4]([CH3:13])[NH:3][C:2]=2[CH3:1])[CH:11]=1)([O:22][CH2:23][CH3:24])=[O:21]

Participants

5

Reactant 3

HCID 10928Ethyl chloroformateHCID 136476759HCID 136476759, compoundHCID 178418339Butyllithium

Product 1

HCID 1360663265-Carboethoxy-3-(2,5-dimethylpyrrolyl)-1-methylpyrazoleYield 60%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

A solution of 3-(2,5-dimethylpyrrolyl)-1-methyl-pyrazole (5.0 g, 28.6 mmol) in dry tetrahydrofuran (250 mL) was cooled to -78° C. Then, n-butyllithium (19.5 mL, 1.6M, 31.2 mmol) was added dropwise over 15 min followed by stirring for 2 h at -78° to -60° C. Ethyl chloroformate (3.58 mL, 37.5 mmol) was added and the solution was warmed to room temperature and stirred 1 h. The solvent was removed at reduced pressure and the residue was partitioned between ether and water. Phases were separated and the organic layer was washed with brine, filtered through a cone of sodium sulfate, and concentrated to leave an oil. This residue was chromatographed on Silica Woelm®TSC (600 g, 15% ether-hexane) to give after an 850 mL forerun, 0.18 of an impurity in 500 mL and 4.69 g of oil in 700 mL. The oil was kugelrohr distilled, 100° to 110° C., (0.15 mm) to give 4.24 g, 60% of 5-carboethoxy-3-(2,5-dimethylpyrrolyl)-1-methylpyrazole as a clear oil; IR (neat) 1728, 1546, 1494, 1273, 1252 cm-1.

Workup

  1. stirringstirred 1 h
  2. customThe solvent was removed at reduced pressure
  3. customthe residue was partitioned between ether and water
  4. customPhases were separated
  5. washthe organic layer was washed with brine
  6. filtrationfiltered through a cone of sodium sulfate
  7. concentrationconcentrated
  8. customto leave an oil
  9. customThis residue was chromatographed on Silica Woelm®TSC (600 g, 15% ether-hexane)
  10. customto give after an 850 mL forerun
  11. distillationkugelrohr distilled, 100° to 110° C.

Sources & evidence

ORD record
ord-b090c6d6ce42486aba30419933808e49
Source dataset
uspto-grants-1989_01
Patent number
US04795817

Reaction notes

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