p-Bromoacetophenone → 1-Bromo-4-(prop-1-en-2-yl)benzene

HRID 855268Notes

Reaction equation

HRID 855268 reaction equation
[Br-].[C:2]1([PH+](C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.[Li]CCCC.[CH3:26][C:27]([C:29]1[CH:34]=[CH:33][C:32]([Br:35])=[CH:31][CH:30]=1)=O>CS(C)=O>[Br:35][C:32]1[CH:33]=[CH:34][C:29]([C:27]([CH3:2])=[CH2:26])=[CH:30][CH:31]=1

Participants

5

Reactant 3

HCID 7466p-BromoacetophenoneHCID 517696Phosphine, triphenyl-, hydrobromideHCID 178418339Butyllithium

Product 1

HCID 36144101-Bromo-4-(prop-1-en-2-yl)benzeneYield 53%

Reagents, catalysts & solvents 1

HCID 679Dimethyl SulfoxideSolvent2×

Procedure

To a solution of triphenylphosphonium bromide (17.94 g, 50.24 mmol) in DMSO (10 ml) was added n-BuLi (39.25 ml, 1.6M solution in hexane, 62.80 mmol). The solution was stirred at rt for 1 h and to this was added a solution of 4-bromoacetophenone (10.00 g, 50.24 mmol) in DMSO (4 ml). The reaction mixture was then stirred at rt overnight and then quenched with water and the product was extracted with pentane. The organic layers were combined washed with brine, dried (MgSO4), filtered and concentrated in vacuo to give a residue which was purified by filtration through a short pad of silica using pentane as eluant to give 1-bromo-4-isopropenylbenzene (5.23 g, 53%) as a colorless oil. 1H NMR (CDCl3, 300 MHz): δ 7.45 (d, J=9.0 Hz, 2H), 7.32 (d, J=9.0 Hz, 2H), 5.36 (m, 1H), 5.10 (m, 1H), 2.12 (m, 3H).

Workup

  1. stirringThe reaction mixture was then stirred at rt overnight
  2. customquenched with water
  3. extractionthe product was extracted with pentane
  4. washThe organic layers were combined washed with brine
  5. dry with materialdried (MgSO4)
  6. filtrationfiltered
  7. concentrationconcentrated in vacuo
  8. customto give a residue which
  9. filtrationwas purified by filtration through a short pad of silica

Sources & evidence

ORD record
ord-79570d942cfa40f5aed0615cfbfef6d1
Source dataset
uspto-grants-2007_08
Patent number
US07259183B2

Reaction notes

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