Reaktion #570467

Reaktionsgleichung

1,2-dibromoethane

hydrochloric acid

2-bromobenzaldehyde

1,2-dibromoethane

1,2-dibromoethane

magnesium

4-iodobenzotrifluoride

→

oil

Ausbeute 136.3%

4'-Trifluoromethyl-2-biphenylcarbaldehyde

Ausbeute 136.3%

Lösungsmittel

THF

THF

THF

THF

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwas added dropwise
2. 2
   Temperaturto maintain gentle reflux
3. 3
   TemperaturThe mixture was then refluxed an additional 20 minutes
4. 4
   Sonstigedecanted into an addition funnel
5. 5
   Sonstigeattached to a second reaction flask
6. 6
   Temperaturthe mixture refluxed for 11/2 hr
7. 7
   Sonstigethe THF evaporated on the rotary evaporator
8. 8
   ExtraktionThe residue was extracted with diethyl ether
9. 9
   ExtraktionThe ether extract
10. 10
    Waschenwas washed with 3N hydrochloric acid (20 mL) water (4×25 mL), and saturated sodium chloride solution (10 mL)
11. 11
    TrocknenThe ether solution was then dried (MgSO4)
12. 12
    workup.ADDITIONtreated with charcoal
13. 13
    Filtrationfiltered
14. 14
    Sonstigeevaporated

Vorschrift

To magnesium turnings (1.23 g, 50.7 mmol) in a dry flask under nitrogen was added anhydrous tetrahydrofuran (THF, 10 mL). The mixture was mechanically stirred while a solution of 1,2-dibromoethane (1.22 g, 6.5 mmol) in THF (10 mL) was added dropwise. Upon completion, a solution of the dimethyl acetal of 2-bromobenzaldehyde (3.00 g, 13.0 mmol) and 1,2-dibromoethane (2.44 g, 13.0 mmol) in THF (10 ml) was added at a rate to maintain gentle reflux. Upon completing, a second solution of 1,2-dibromoethane (1.22 g, 6.5 mmol) in THF (10 mL) was added dropwise. The mixture was then refluxed an additional 20 minutes and decanted into an addition funnel attached to a second reaction flask containing a solution of 4-iodobenzotrifluoride (2.72 g, 10.0 mmol) and iodo(4-trifluoromethyl)bis(triphenylphosphine)palladium (II) (0.21 g, 0.9 mmol) in refluxing THF (20 mL). The Grignard reagent was added dropwise and the mixture refluxed for 11/2 hr. After cooling to room temperature, 3N hydrochloric acid was added (30 mL) and the THF evaporated on the rotary evaporator. The residue was extracted with diethyl ether. The ether extract was washed with 3N hydrochloric acid (20 mL) water (4×25 mL), and saturated sodium chloride solution (10 mL). The ether solution was then dried (MgSO4), treated with charcoal, filtered and evaporated to give a dark yellow oil (3.41 g). This was chromatographed on the Waters Prep 500 HPLC using a 1:1 mixture of methylene chloride and hexane. The product was isolated after evaporation of solvent as a light yellow oil (2.41 g, 96.4%). 'H NMR (CDCl3): 7.6 (m, 7, Ar--H), 8.0 (m, 1, 3-H), 9.9 (s, 1, CHO).

Quelle