Hydrochloric Acid → ethyl 1-cyclopentyl-5-methyl-1H-pyrazole-4-carboxylate

HRID 1098582Notes

Reaction equation

HRID 1098582 reaction equation
C(O[C:6]([NH:8][NH:9][CH:10]1[CH2:14][CH2:13][CH2:12][CH2:11]1)=O)(C)(C)C.Cl.[C:16]([C:19](=CN(C)C)[C:20]([O:22][CH2:23][CH3:24])=[O:21])(=O)[CH3:17]>C(O)C>[CH:10]1([N:9]2[C:16]([CH3:17])=[C:19]([C:20]([O:22][CH2:23][CH3:24])=[O:21])[CH:6]=[N:8]2)[CH2:11][CH2:12][CH2:13][CH2:14]1

Participants

5

Reactant 3

HCID 313Hydrochloric AcidHCID 3806790Ethyl 2-acetyl-3-(dimethylamino)acrylateHCID 23113328tert-Butyl 2-Cyclopentylhydrazinecarboxylate

Product 1

HCID 63235031ethyl 1-cyclopentyl-5-methyl-1H-pyrazole-4-carboxylateYield 76.3%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

To a solution of 1-cyclopentylhydrazine-2-carboxylic acid tert-butyl ester (18.4 g, 92 mmol) in a mixture of ethanol (300 mL) and conc. HCl (7.7 mL, 92 mmol) was added ethyl 2-acetyl-3-(dimethylamino)acrylate (25.5 g, 0.138 mol). The resulting mixture was refluxed for 2 h. The reaction was concentrated in vacuo, dissolved in CH2Cl2 (300 mL), washed with satd NaHCO3, and brine, dried (Na2SO4), concentrated in vacuo and purified by chromatography on silica gel to give ethyl 1-cyclopentyl-5-methyl-1H-pyrazole-4-carboxylate (15.6 g, 76% yield). 1H NMR (400 MHz, DMSO-d6): δ 8.15 (s, 1 H), 4.61 (m, 1 H), 4.15 (q, J=8 Hz, 2 H), 2.29 (s, 3 H), 2.04-1.97 (m, 2 H), 1.89-1.85 (m, 2 H), 1.78-1.71 (m, 2 H), 1.62-1.59 (m, 2 H), 1.23 (t, J=8 Hz, 3 H).

Workup

  1. temperatureThe resulting mixture was refluxed for 2 h
  2. concentrationThe reaction was concentrated in vacuo
  3. dissolutiondissolved in CH2Cl2 (300 mL)
  4. washwashed with satd NaHCO3, and brine
  5. dry with materialdried (Na2SO4)
  6. concentrationconcentrated in vacuo
  7. custompurified by chromatography on silica gel

Sources & evidence

ORD record
ord-ed0965a4082248eea0ca6171fa9d591c
Source dataset
uspto-grants-2012_03
Patent number
US08143293B2

Reaction notes

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