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

Participants

Reaction Steps

To a stirred solution of 3-bromo-4-methylbenzonitrile (3.5 g, 17.86 mmol) in dry THF at −78° C. was added n-BuLi (2N, 10.71 mL) dropwise. The mixture was stirred for 15 min., and added triisopropyl borate (6.71 g, 35.71 mmol). The reaction flask was kept in the cooling bath for 30 min., and at room temperature for 3 hours. The solvent was removed, and the residue was dissolved in ether. The organic phase was washed with 1N HCl solution and water, dried over Na2SO4, and filtered. The filtrate was concentrated in vacuo, and the residue was crystallized from a 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 (s, 3H).

Provenance & Evidence