Реакция #487556

Уравнение реакции

hydrochloric acid

n-Butyllithium

3-Bromo-4′-chloro-4-ethylbiphenyl

trimethylborate

→

4′-chloro-4-ethylbiphen-3-ylboronic acid

Выход 69.1%

Растворители

tetrahydrofuran

Условия реакции

Обработка

1. 1
   workup.ADDITIONis added dropwise over 30 minutes
2. 2
   workup.STIRRINGthe reaction mixture is stirred for two hours
3. 3
   workup.ADDITIONonce the addition
4. 4
   workup.STIRRINGis stirred for two hours
5. 5
   КонцентрированиеThe mixture is concentrated
6. 6
   Другоеto remove most of the tetrahydrofuran
7. 7
   workup.ADDITIONdiluted with water
8. 8
   Экстракцияextracted with diethyl ether
9. 9
   ПромывкаThe organic extracts are washed with water and brine
10. 10
    Сушкаdried over anhydrous sodium sulfate
11. 11
    Фильтрацияfiltered
12. 12
    Другоеthe filtrate is evaporated in vacuo
13. 13
    ДругоеThe residue is further purified by flash column chromatography on silica gel
14. 14
    Промывкаeluting with 7% ethyl acetate in hexane

Методика

3-Bromo-4′-chloro-4-ethylbiphenyl (10 g, 0.03 mol) is dissolved in tetrahydrofuran (250 ml), and the temperature is cooled to −78° C. n-Butyllithium (1.33 molar solution in hexanes, 34.6 ml) is added dropwise over 30 minutes, maintaining the temperature at around −78° C. The reaction mixture is stirred for one and a half hours, then trimethylborate (4.9 g, 0.05 mol) is added dropwise and the reaction mixture is stirred for two hours. A solution of 2N aqueous hydrochloric acid (100 ml) is added dropwise, and once the addition is complete the mixture is stirred for two hours. The mixture is concentrated to remove most of the tetrahydrofuran, then diluted with water and extracted with diethyl ether. The organic extracts are washed with water and brine, combined, dried over anhydrous sodium sulfate, filtered and the filtrate is evaporated in vacuo. The residue is further purified by flash column chromatography on silica gel, eluting with 7% ethyl acetate in hexane to give 4′-chloro-4-ethylbiphen-3-ylboronic acid (5.4 g).

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