Hydrochloric Acid → 1-cyclopentyl-1H-pyrazole

HRID 1930389Notes

Reaction equation

HRID 1930389 reaction equation
CO[CH:3](OC)[CH2:4]C(OC)OC.[CH:12]1([NH:17][NH:18][C:19](OC(C)(C)C)=O)[CH2:16][CH2:15][CH2:14][CH2:13]1.Cl>O>[CH:12]1([N:17]2[CH:4]=[CH:3][CH:19]=[N:18]2)[CH2:13][CH2:14][CH2:15][CH2:16]1

Participants

5

Reactant 3

HCID 313Hydrochloric AcidHCID 66019TetramethoxypropaneHCID 23113328tert-Butyl 2-Cyclopentylhydrazinecarboxylate

Product 1

HCID 108444351-cyclopentyl-1H-pyrazoleYield 71%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

A mixture of 1,1,3,3-tetramethoxypropane (13.6 g, 83 mmol) and N2-cyclopentyl-N1-(tert-butoxycarbonyl)hydrazine (16.6 g, 83 mmol, see Ranatunge et al., J. Med. Chem. (2004), 47, p2180-2193) in water (150 mL) was treated with cone. HCl (21 mL, 252 mmol). The resulting mixture was heated at reflux overnight. The completed reaction mixture was extracted with ether and the extracts were washed with brine, dried over anhydrous MgSO4, and concentrated in vacuo to give 1-cyclopentyl-1 H-pyrazole (8.0 g, 71% yield. 1H NMR (400 MHz, CDCl3): δ 7.52 (s, 1 H), 7.43 (s, 1 H), 6.24 (s, 1 H), 4.68 (m, 1 H), 2.20-1.71 (m, 8 H). MS (ESI) m/z; 137.1 [M+H+].

Workup

  1. additionwas treated with cone
  2. temperatureThe resulting mixture was heated
  3. temperatureat reflux overnight
  4. customThe completed reaction mixture
  5. extractionwas extracted with ether
  6. washthe extracts were washed with brine
  7. dry with materialdried over anhydrous MgSO4
  8. concentrationconcentrated in vacuo

Sources & evidence

ORD record
ord-fea1f5478c13454b9fa6f77671454262
Source dataset
uspto-grants-2012_05
Patent number
US08188113B2

Reaction notes

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