Reaktion #487556

Reaktionsgleichung

hydrochloric acid

n-Butyllithium

3-Bromo-4′-chloro-4-ethylbiphenyl

trimethylborate

→

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

Ausbeute 69.1%

Lösungsmittel

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

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
   EinengenThe mixture is concentrated
6. 6
   Sonstigeto remove most of the tetrahydrofuran
7. 7
   workup.ADDITIONdiluted with water
8. 8
   Extraktionextracted with diethyl ether
9. 9
   WaschenThe organic extracts are washed with water and brine
10. 10
    Trocknendried over anhydrous sodium sulfate
11. 11
    Filtrationfiltered
12. 12
    Sonstigethe filtrate is evaporated in vacuo
13. 13
    SonstigeThe residue is further purified by flash column chromatography on silica gel
14. 14
    Wascheneluting with 7% ethyl acetate in hexane

Vorschrift

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).

Quelle