5-Bromo-2-methylbenzonitrile (40 g, 204 mmol), bis(pinacolato)diboron (69.2 g, 306 mmol), potassium acetate (60 g, 612 mmol), PdCl2(dppf) (7.6 g, 20.8 mmol) and 1,4-dioxane (500 mL) were added in a 1 L single-neck flask, and the reaction mixture was heated to react at 100 ℃ for 2 hours.
After completion of the reaction, the mixture was cooled to room temperature, then water (250 mL) was added.
The mixture was extracted with ethyl acetate (3?250 mL), and the organic layers were concentrated in vacuo to remove the solvent.
The residue was separated by a silica gel column (petroleum ether: ethyl acetate = 30:1) to give 3-Cyano-4-methylphenylboronic acid, pinacol ester.
