Bromine → 1-Methyl[[1,1'-bi(cyclopentan)]-3-en]-2-one

HRID 1576582Notes

Reaction equation

HRID 1576582 reaction equation
[CH:1]1([C:6]2([CH3:12])[CH2:10][CH2:9][CH2:8][C:7]2=[O:11])[CH2:5][CH2:4][CH2:3][CH2:2]1.BrBr.S(=O)(O)[O-].[Na+]>C(Cl)(Cl)Cl>[CH:1]1([C:6]2([CH3:12])[C:7](=[O:11])[CH:8]=[CH:9][CH2:10]2)[CH2:5][CH2:4][CH2:3][CH2:2]1

Participants

5

Reactant 3

HCID 24408BromineHCID 215114981-Methyl[1,1'-bi(cyclopentane)]-2-oneHCID 23665763Sodium Bisulfite

Product 1

HCID 215114971-Methyl[[1,1'-bi(cyclopentan)]-3-en]-2-one

Reagents, catalysts & solvents 1

HCID 6212ChloroformSolvent

Procedure

Four grams (0.026 mole) of 2-cyclopentyl-2-methyl-cyclopentanone dissolved in 20 ml. of chloroform is cooled to 0°C. and 4.2 g. (0.026 mole) of bromine is added over a 40 minute interval. An aqueous 5 wt. % solution of sodium bisulfite is added to destroy the excess bromine followed by 10 wt. % aqueous sodium hydroxide solution to achieve a pH of 7. The aqueous layer is discarded after back extraction with 20 ml. of chloroform. After washing the combined chloroform layers with water and drying over magnesium sulfate, the chloroform is removed at reduced pressure. Pyridine, 20 ml., is added and the solution is refluxed for one hour, cooled and diluted with 100 ml. water. 100 Ml. of chloroform is added and the layers are separated. The chloroform layer is washed with 50 ml. of 6 molar HCl and then dried over magnesium sulfate. Evaporation gives 5-cyclopentyl-5-methyl-2-cyclopentenone suitable for use in the Diels-Alder reaction of Step 1.

Workup

  1. customto destroy the excess bromine
  2. extractionafter back extraction with 20 ml
  3. washAfter washing the combined chloroform layers with water
  4. dry with materialdrying over magnesium sulfate
  5. customthe chloroform is removed at reduced pressure
  6. addition, is added
  7. temperaturethe solution is refluxed for one hour
  8. temperaturecooled
  9. additiondiluted with 100 ml
  10. additionof chloroform is added
  11. customthe layers are separated
  12. washThe chloroform layer is washed with 50 ml
  13. dry with materialof 6 molar HCl and then dried over magnesium sulfate
  14. customEvaporation

Sources & evidence

ORD record
ord-0c2f9b095602433dbb4fb12996235a35
Source dataset
uspto-grants-1976_09
Patent number
US03981911

Reaction notes

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