p-Toluenesulfonic acid → 5-(1-Cyclopentenyl)pentan-2-one

HRID 2185163Notes

Reaction equation

HRID 2185163 reaction equation
[C:1]1(=[CH:6][CH2:7][CH2:8][C:9](=[O:11])[CH3:10])[CH2:5][CH2:4][CH2:3][CH2:2]1.CC1C=CC(S(O)(=O)=O)=CC=1>C1(C)C=CC=CC=1.CC(OC)(C)C>[C:1]1([CH2:6][CH2:7][CH2:8][C:9](=[O:11])[CH3:10])[CH2:5][CH2:4][CH2:3][CH:2]=1

Participants

5

Reactant 2

HCID 6101p-Toluenesulfonic acidHCID 135280135-Cyclopentylidenepentan-2-one

Product 1

HCID 135280095-(1-Cyclopentenyl)pentan-2-oneYield 72.1%

Reagents, catalysts & solvents 2

HCID 1140TolueneSolventHCID 15413tert-Butyl methyl etherSolvent

Conditions

Temperature
90 °C

Procedure

A mixture of 5-cyclopentylidene-2-pentanone (9.92 g; 65 mmol) and p-TsOH (100 mg; 0.53 mmol) in toluene (150 ml) was heated at 90° C. for 8 hours, then cooled down to room temperature, diluted with MTBE (100 ml), washed with saturated NaHCO3 (50 ml), H2O (50 ml), brine (50 ml), dried over MgSO4 and concentrated in vacuo. Distillation under reduced pressure (48° C./0.065 torr) yielded 7.13 g of 5-(cyclopent-1-enyl)-2-pentanone (purity about 80%), which was further purified by flash chromatography to give 6.1 g (61% yield) of a 89% pure product containing 11% of 5-cyclopentylidene-2-pentanone.

Workup

  1. temperaturecooled down to room temperature
  2. washwashed with saturated NaHCO3 (50 ml), H2O (50 ml), brine (50 ml)
  3. dry with materialdried over MgSO4
  4. concentrationconcentrated in vacuo
  5. distillationDistillation under reduced pressure (48° C./0.065 torr)

Sources & evidence

ORD record
ord-74036c35ea5443259811297d2d5a8373
Source dataset
uspto-grants-2002_06
Patent number
US06399811B1

Reaction notes

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