Triisopropyl borate → (5-Cyano-2-methylphenyl)boronic acid

Participants

Reaction Steps

A stirred solution of 3-bromo-4-methylbenzonitrile (3.5 g, 17.86 mmol) in dry THF was added n-BuLi (10.71 mL) slution dropwise at −78° C., and the mixture was stirred for 15 minutes, followed by the addition of triisopropyl borate (6.71 g, 35.71 mmol) in one portion. The reaction flask was kept in a cooling bath for 30 min., and room temperature for 3 hours. The solvent was removed, and the residue was dissolved in ether. The solution was washed with 1N HCl solution and water, dried over Na2SO4, filtered, and concentrated in vacuo. The residue was purified by recrystallyzation from the mixture of CH2Cl2 and hexane to give 5-cyano-2-methylphenylboronic acid (800 mg, 20%). 1H-NMR (CDCl3 400 MHz): δ7.50-7.78 (m, 2H), 7.30 (d, 1H), 2.42 (d, 3H).

Provenance & Evidence