To a suspension of NaH (1.23 g, 28.2 mmol, 1.2 eq., 60% content) in THF (10 mL) was slowly added dropwise a solution of 1-(2-bromophenyl)prop-2-en-1-ol (5.0 g, 23.5 mmol, 1.0 eq.) in THF (10 mL) at 0 °C. After dropwise addition, the reaction mixture was stirred for 1 hour and subsequently cooled to -70 °C. At this temperature, n-butyllithium (n-BuLi, 11.3 mL, 28.2 mmol, 1.2 eq., 2.5 M solution in THF) was slowly added and stirring was continued for 1 hour. Subsequently, triisopropyl borate (5.3 g, 28.2 mmol, 1.2 eq.) was added and the reaction mixture continued to stir for 5 hours. Upon completion of the reaction, the reaction was quenched with 2N H2SO4 and the mixture was partitioned between saturated saline and ethyl acetate. The organic layer was washed with saturated saline, dried over anhydrous Na2SO4, filtered and concentrated. The residue was purified by column chromatography to afford the target product 3-vinylbenzo[c][1,2]oxaborolan-1(3H)-ol (2.2 g, 57% yield). lc-MS (m/z) = 158.9, 160.9 [M + H]+.
![3-vinylbenzo[c][1,2]oxaborol-1(3H)-ol](/CAS/GIF/952149-27-8.gif)