Reaktion #958996

Reaktionsgleichung

HCl

n-Butyllithium

2,2-diphenylvinyl bromide

n-Butyl borate

→

2,2-diphenylvinyl boronic acid

Lösungsmittel

hexane

THF

Water

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwas added at −78° C. before the mixture
2. 2
   workup.STIRRINGwas then stirred for 3 h
3. 3
   ExtraktionThe reaction mixture was extracted with EtOAc
4. 4
   Trocknenthe combined organic phases were dried over MgSO4
5. 5
   EinengenConcentration under reduced pressure

Vorschrift

n-Butyllithium in hexane (2.5 M, 20 mL) was added slowly under nitrogen to a stirred solution of 2,2-diphenylvinyl bromide (6.50 g, 25.1 mmol) in THF (40 mL) at −78° C. and then the mixture was stirred further for 1 h. n-Butyl borate (15 mL, 55.5 mmol) was added at −78° C. before the mixture was warmed slowly to room temperature and stirred overnight. Water (50 mL) was added, followed by conc. HCl (100 mL) to acidify the mixture, which was then stirred for 3 h. The reaction mixture was extracted with EtOAc and the combined organic phases were dried over MgSO4. Concentration under reduced pressure gave 2,2-diphenylvinyl boronic acid, which, without further purification, was reacted with pinacol (4.25 g, 36.0 mmol) in toluene under reflux for 2 h to effect condensation by the azeotropic removal of the water formed. The mixture was concentrated under reduced pressure and the residue was purified by column chromatography (hexanes/CH2Cl2=1/1) to afford C (4.10 g, 53%) as transparent liquid.

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