Reaction #2139947

Reaction equation

4-pentylcyclohexanone

n-butyllithium

1-bromo-3-fluoro-4-iodobenzene

hydrochloric acid

→

4-bromo-2-fluoro-1-(4-pentylcyclohex-1-enyl)benzene

Yield 58.0%

Solvents

tetrahydrofuran

hexane

tetrahydrofuran

water

Conditions

Workup

1. 1
   workup.WAITthe batch was left
2. 2
   workup.WAITto stirr for 60 minutes
3. 3
   OtherThe organic phase was separated off
4. 4
   Washwashed with water
5. 5
   Dryingdried over sodium sulfate
6. 6
   Otherthe solvent was removed under reduced pressure
7. 7
   workup.DISSOLUTIONThe crude product was subsequently dissolved in 1.4 l of toluene
8. 8
   workup.ADDITIONafter addition of 6 g of toluenesulfonic acid
9. 9
   Temperatureheated on a water
10. 10
    Otherseparator until water of reaction
11. 11
    Otherno longer separated off
12. 12
    WashThe solution was washed with water
13. 13
    Otherevaporated
14. 14
    Filtrationthe residue was filtered through silica gel with n-heptane

Procedure

200 g (0.665 mol) of 1-bromo-3-fluoro-4-iodobenzene were dissolved in 800 ml of tetrahydrofuran, and 440 ml (0.698 mmol) of a 15 percent solution of n-butyllithium in hexane were added dropwise at −70° C. After 30 minutes, a solution of 117 g (0.698 mol) of 4-pentylcyclohexanone in 200 ml of tetrahydrofuran was added, and the batch was left to stirr for 60 minutes, hydrolysed using water and acidified using conc. hydrochloric acid. The organic phase was separated off, washed with water and dried over sodium sulfate, and the solvent was removed under reduced pressure. The crude product was subsequently dissolved in 1.4 l of toluene and, after addition of 6 g of toluenesulfonic acid, heated on a water separator until water of reaction was no longer separated off. The solution was washed with water and evaporated, and the residue was filtered through silica gel with n-heptane, giving 124 g (58%) of 4-bromo-2-fluoro-1-(4-pentylcyclohex-1-enyl)benzene as a yellow oil.

Source