Reaction #487556

Reaction equation

hydrochloric acid

n-Butyllithium

3-Bromo-4′-chloro-4-ethylbiphenyl

trimethylborate

→

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

Yield 69.1%

Solvents

tetrahydrofuran

Conditions

Workup

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
   ConcentrationThe mixture is concentrated
6. 6
   Otherto remove most of the tetrahydrofuran
7. 7
   workup.ADDITIONdiluted with water
8. 8
   Extractionextracted with diethyl ether
9. 9
   WashThe organic extracts are washed with water and brine
10. 10
    Dryingdried over anhydrous sodium sulfate
11. 11
    Filtrationfiltered
12. 12
    Otherthe filtrate is evaporated in vacuo
13. 13
    OtherThe residue is further purified by flash column chromatography on silica gel
14. 14
    Washeluting with 7% ethyl acetate in hexane

Procedure

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).

Source