Lithium Bromide → 3,3-DI(3-Butenyl)cyclopentanone

HRID 2070563Notes

Reaction equation

HRID 2070563 reaction equation
[Br-].[Li+].[CH2:3]([Mg]Br)[CH2:4][CH:5]=[CH2:6].[CH2:9]([C:13]1[CH2:17][CH2:16][C:15](=[O:18])[CH:14]=1)[CH2:10][CH:11]=[CH2:12]>O1CCCC1.[Cu]I>[CH2:3]([C:13]1([CH2:9][CH2:10][CH:11]=[CH2:12])[CH2:17][CH2:16][C:15](=[O:18])[CH2:14]1)[CH2:4][CH:5]=[CH2:6]

Participants

6

Reactant 3

HCID 82050Lithium BromideHCID 12739856HCID 12739856, compoundHCID 178418797HCID 178418797, compound

Product 1

HCID 125830723,3-DI(3-Butenyl)cyclopentanone

Reagents, catalysts & solvents 2

HCID 24350Copper(1+) iodide; Copper(I) iodide; Cuprous iodide; Cuprous iodide (CuI)CatalystHCID 8028TetrahydrofuranSolvent2×

Conditions

Temperature
-78 °C

Procedure

To a suspension of copper(I) iodide (2.6 g) and lithium bromide (1.2 g) in tetrahydrofuran (25 mL) was added dropwise a 0.5M tetrahydrofuran solution of 3-butenylmagnesium bromide (26.5 mL) under nitrogen atmosphere at −78° C. over 6 minutes, followed by stirring the reaction mixture at −78° C. for 40 minutes. Then, 5 minutes after addition of boron trifluoride diethyl ether complex (0.554 mL), to the reaction mixture was added 3-(3-butenyl)cyclopent-2-enone (0.6 g) obtained in Step 1. Half an hour later, after addition of boron trifluoride diethyl ether complex (0.250 mL), the reaction mixture was stirred at −78° C. for 2 hours, and further stirred at room temperature overnight after removing a dry-ice/ethanol bath. Then, after addition of saturated aqueous ammonium chloride solution and 28% aqueous ammonia solution, the reaction mixture was extracted with ethyl acetate. The organic layer was washed successively with aqueous ammonia solution and saturated brine, dried and concentrated. The residue was purified by column chromatography on silica gel to give 3,3-dibut-3-enylcyclopentanone (380 mg).

Workup

  1. additionThen, 5 minutes after addition of boron trifluoride diethyl ether complex (0.554 mL)
  2. additionHalf an hour later, after addition of boron trifluoride diethyl ether complex (0.250 mL)
  3. stirringthe reaction mixture was stirred at −78° C. for 2 hours
  4. stirringfurther stirred at room temperature overnight
  5. customafter removing a dry-ice/ethanol bath
  6. additionThen, after addition of saturated aqueous ammonium chloride solution and 28% aqueous ammonia solution
  7. extractionthe reaction mixture was extracted with ethyl acetate
  8. washThe organic layer was washed successively with aqueous ammonia solution and saturated brine
  9. customdried
  10. concentrationconcentrated
  11. customThe residue was purified by column chromatography on silica gel

Sources & evidence

ORD record
ord-8e3daf4ed3c04a8085a78e694e860613
Source dataset
uspto-grants-2012_10
Patent number
US08299296B2

Reaction notes

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