Hydrochloric Acid → 4-(Benzyloxy)-2-vinylphenylboronic acid

Participants

Reaction Steps

Triisopropyl borate (683 mg, 3.63 mmol) was added to a stirred solution of 4-(benzyloxy)-1-bromo-2-vinylbenzene (1.0 g, 0.346 mmol) in THF (9 mL). The solution was cooled in a CO2/acetone bath. A solution of n-butyllithium (1.45 mL of 2.5M in hexanes, 3.63 mmol) was added dropwise over 5 minutes. The cooling bath was left in place and was allowed to warm to room temperature. The mixture was treated with HCl (5 mL of 1N) and water (5 mL), stirred for 1 hour, and extracted with ethyl acetate (3×15 mL). The combined extracts were washed with brine, dried (MgSO4), filtered, and concentrated to an oil which crystallized from diethyl ether/hexanes to provide colorless crystals of the desired product (530 mg, 57% yield). 1H NMR (300 MHz, CDCl3) δ 5.14 (s, 2H), 5.34 (d, J=12.44 Hz, 1H), 5.68 (d, J=17.57 Hz, 1H), 6.97 (dd, J=8.42, 2.56 Hz, 1H), 7.36 (m, 6H), 7.83 (dd, J=17.57, 10.98 Hz, 1H), 8.16 (d, J=8.42 Hz, 1H).

Provenance & Evidence