Reaktion #75919

Reaktionsgleichung

bromine

water

1-[3,5-difluoro-4-(methylthio)-phenyl]ethanone

1-[3,5-difluoro-4-(methyl-thio)phenyl]ethanone

bromine

water

→

2-bromo-1-[3,5-difluoro-4-(methylthio)-phenyl]ethanone

Ausbeute 86.0%

Lösungsmittel

HBr

acetic acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   Extraktionextracted with ethyl acetate (1×250 mL, 1×100 mL)
2. 2
   WaschenThe combined extracts were washed with dilute sodium chloride solution
3. 3
   Trocknendried with magnesium sulfate
4. 4
   Einengenconcentrated
5. 5
   workup.ADDITIONTo the residue was added hexanes (100 mL)
6. 6
   Einengenthe mixture concentrated
7. 7
   workup.DISSOLUTIONThe residue was dissolved in 30% HBr in acetic acid (10 mL)
8. 8
   workup.STIRRINGAfter stirring at room temperature for 30 minutes
9. 9
   Extraktionextracted with dichloromethane (1×200 mL, 1×100 mL)
10. 10
    WaschenThe combined extracts were washed with water
11. 11
    Trocknendried with magnesium sulfate
12. 12
    Einengenconcentrated
13. 13
    workup.ADDITIONTo the residue was added hexanes (100 mL)
14. 14
    Einengenthe mixture concentrated
15. 15
    SonstigePurification of the product by silica gel chromatography

Vorschrift

To a solution of 1-[3,5-difluoro-4-(methylthio)-phenyl]ethanone (prepared in Step 1 of Example 1) (6.2 g, 30 mmol) in 30% HBr in acetic acid (10 mL) was added bromine (4.8 g, 30 mmol) dropwise, and the reaction mixture stirred at room temperature for 45 minutes. The mixture was treated with water and extracted with ethyl acetate (1×250 mL, 1×100 mL). The combined extracts were washed with dilute sodium chloride solution, dried with magnesium sulfate, and concentrated. To the residue was added hexanes (100 mL) and the mixture concentrated. The residue was dissolved in 30% HBr in acetic acid (10 mL) and treated with bromine (0.80 g, 5.0 mmol). After stirring at room temperature for 30 minutes, the mixture was treated with water and extracted with dichloromethane (1×200 mL, 1×100 mL). The combined extracts were washed with water, dried with magnesium sulfate and concentrated. To the residue was added hexanes (100 mL), and the mixture concentrated. Purification of the product by silica gel chromatography using 10% ethyl acetate in hexanes gave 2-bromo-1-[3,5-difluoro-4-(methylthio)-phenyl]ethanone as an orange solid (7.2 g, 86%), MP 30.5-33.2° C. 1H NMR (CDCl3/400 MHz) 7.46-7.50 (m, 2H), 4.33 (s, 2H), 2.57 (t, 3H, J=1.1). ESHRMS m/z 278.9260 (M−H+, Calcd 278.9291). Anal. Calcd for C9H7BrF2OS: C, 38.45; H, 2.52. Found: C, 38.19; H, 2.34.

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