Reaction #1833246

Reaction equation

4-bromo-5-fluoro-2-methoxyphenol

Boron tribromide

→

4-bromo-5-fluorobenzene-1,2-diol

Yield 96.1%

Solvents

CH2Cl2

Conditions

Workup

1. 1
   Otherthe ice/water bath was removed
2. 2
   Temperatureto warm to room temperature
3. 3
   OtherThe reaction mixture was placed in an ice/water bath
4. 4
   workup.ADDITIONmethanol (30 mL) was slowly added via syringe
5. 5
   OtherUpon removal of the ice/water bath
6. 6
   Temperatureto warm to room temperature
7. 7
   OtherThe reaction mixture was transferred to a separatory funnel
8. 8
   workup.ADDITIONdiluted with ethyl acetate (200 mL)
9. 9
   Washwashed with water (200 mL)
10. 10
    DryingThe organic layer was dried over Na2SO4
11. 11
    Filtrationfiltered

Procedure

To CH2Cl2 (30 mL) in a 50 mL round bottom flask was added 4-bromo-5-fluoro-2-methoxyphenol (2 g, 9.05 mmol). The reaction mixture was cooled to 0° C. in an ice/water bath. Boron tribromide (1.027 mL, 10.86 mmol) was slowly added via syringe over 5 min, and the ice/water bath was removed. The reaction mixture was allowed to warm to room temperature and was stirred for 18 h. The reaction mixture was placed in an ice/water bath and methanol (30 mL) was slowly added via syringe. Upon removal of the ice/water bath, the reaction mixture was allowed to warm to room temperature. The reaction mixture was transferred to a separatory funnel, diluted with ethyl acetate (200 mL) and washed with water (200 mL). The organic layer was dried over Na2SO4 and filtered. Concentration of the organic solution gave 4-bromo-5-fluorobenzene-1,2-diol as a dark brown oil (1.8 g, 96%): 1H NMR (400 MHz, CDCl3) δ 7.03 (d, J=6.5 Hz, 1H), 6.72 (dd, J=8.3, 3.5 Hz, 1H); 19F NMR (376 MHz, CDCl3) δ −115.91 (s); ESIMS m/z 207 ([M+H]+), 206 ([M−H]−).

Source