Hydrochloric Acid → 1,2,2-Triphenylvinylboronic acid

Participants

Reaction Steps

n-Butyllithium in hexane (2.5 M, 15 mL) was added slowly under nitrogen to a stirred solution of (2-bromoethene-1,1,2-triyl)tribenzene (5.00 g, 14.9 mmol) in THF (50 mL) at −78° C. and then the mixture was stirred further for 1 h. Tributyl borate (11.0 mL, 40.8 mmol) was added at −78° C. before the mixture was warmed slowly to room temperature and stirred for 8 hours. Water (100 mL) was added, followed by conc. HCl (100 mL) to acidify the mixture, which was then stirred for 2 hours. The reaction mixture was extracted with EtOAc and the combined organic phases were dried over MgSO4. Concentration under reduced pressure gave 1,2,2-triphenylvinylboronic acid, which, without further purification, was reacted with pinacol (1.73 g, 14.6 mmol) in toluene under reflux for 2 hours 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/EtOAc=20/1) to afford D (2.41 g, 65%) as white solid.

Provenance & Evidence