3-Phenylprop-2-Enal → 5-Phenyl-4,5-dihydro-1H-pyrazole

HRID 12495

Reaction equation

HRID 12495 reaction equation
O.[NH2:2][NH2:3].[CH:4](=O)[CH:5]=[CH:6][C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1>CC(O)(C)C>[C:7]1([CH:6]2[NH:3][N:2]=[CH:4][CH2:5]2)[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1

Participants

4

Reactant 2

HCID 3073-Phenylprop-2-EnalHCID 24654Hydrazine hydrate (1:1)

Product 1

HCID 1208415-Phenyl-4,5-dihydro-1H-pyrazole

Reagents, catalysts & solvents 1

HCID 6386tert-ButanolSolvent

Procedure

Under N2 atmosphere, hydrazine hydrate (9.2 mL) was added to a solution of cinnamaldehyde (10.0 g) in t-BuOH (20 mL). The mixture was refluxed overnight, followed by concentration under reduced pressure. Water was added to the residue, and the aqueous phase was extracted twice with DCM. The combined organic layers were washed with water, dried over Na2SO4 and concentrated under reduced pressure. This gave 10.46 g of a yellow oil containing 85% of the desired product, which was used in subsequent steps without further purification. 1H NMR (200 MHz, CDCl3) δ 2.61-2.80 (m, 1H), 3.04-3.23 (m, 1H), 4.72 (dd, J=8 and 10 Hz, 1H), 5.60-6.10 (br s, 1H), 6.77-6.87 (m, 1H), 7.18-7.47 (m, 5H).

Workup

  1. temperatureThe mixture was refluxed overnight
  2. concentrationfollowed by concentration under reduced pressure
  3. additionWater was added to the residue
  4. extractionthe aqueous phase was extracted twice with DCM
  5. washThe combined organic layers were washed with water
  6. dry with materialdried over Na2SO4
  7. concentrationconcentrated under reduced pressure
  8. additionThis gave 10.46 g of a yellow oil containing 85% of the desired product, which
  9. customwas used in subsequent steps without further purification

Sources & evidence

ORD record
ord-cc69153d0baf4ca4ad6a0b45e3ed5cb5
Source dataset
uspto-grants-2010_06
Patent number
US07728018B2

Linked notes

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