Reaction #47357

Reaction equation

3-(2,5-difluoro-phenoxy)-but-2-enoic acid ethyl ester

N-bromosuccinimide

→

4-bromo-3-(2,5-difluoro-phenoxy)-but-2-enoic acid ethyl ester

Yield 87.2%

Solvents

carbon tetrachloride

Conditions

Workup

1. 1
   TemperatureThe reaction was then heated
2. 2
   TemperatureAt this time, the reaction was cooled to 25° C.
3. 3
   Otherwas placed in the refrigerator overnight
4. 4
   OtherAt this time, the reaction was removed from the refrigerator
5. 5
   OtherThe resulting precipitate was removed by filtration
6. 6
   Washwas rinsed with carbon tetrachloride (25 mL)
7. 7
   ConcentrationThe filtrate was concentrated in vacuo
8. 8
   OtherPurification by Analogix flash chromatography (40 g, 2% ethyl acetate/hexanes)

Procedure

A solution of 3-(2,5-difluoro-phenoxy)-but-2-enoic acid ethyl ester (1.35 g, 5.57 mmol) in carbon tetrachloride (30.9 mL) was treated with N-bromosuccinimide (1.09 g, 6.13 mmol) and benzoyl peroxide (108 mg, 0.44 mmol). The reaction was then heated to reflux (105° C.) for 5 h. At this time, the reaction was cooled to 25° C. and then was placed in the refrigerator overnight. At this time, the reaction was removed from the refrigerator. The resulting precipitate was removed by filtration and was rinsed with carbon tetrachloride (25 mL). The filtrate was concentrated in vacuo. Purification by Analogix flash chromatography (40 g, 2% ethyl acetate/hexanes) afforded impure 4-bromo-3-(2,5-difluoro-phenoxy)-but-2-enoic acid ethyl ester (1.56 g, 87%) as a clear oil. The material was used without further purification.

Source