3-Fluoro-2-(4,4,5,5-tetraMethyl-1,3,2-dioxaborolan-2-yl)benzonitrile

73183-34-3

425379-16-4

624741-47-5

2-Bromo-3-fluorobenzonitrile (1.20 g, 6.00 mmol), dried potassium acetate (1.18 g, 12.0 mmol) and bis(pinacolato)diboron (1.75 g, 6.89 mmol) were mixed in 1,4-dioxane (14.7 ml). The mixture was degassed by nitrogen bubbling for 50 min, followed by addition of dimethyl sulfoxide (0.3 ml). Dichloro[1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloromethane adduct (0.1481 g, 0.181 mmol) was then added and again degassed for 10 min. The reaction mixture was heated at 90°C for 18 hours in a nitrogen atmosphere. After completion of the reaction, it was cooled to room temperature, filtered through glass fiber paper and the solids were washed with a small amount of dichloromethane. The filtrates were combined and concentrated by vacuum evaporation. The residue was partitioned between 2M NaOH aqueous solution (21 ml) and ether (20 ml). The aqueous layer was acidified to pH 5 with concentrated hydrochloric acid (3 ml) to induce precipitation of the solid. The mixture was allowed to stand in a refrigerator for 3 days, the precipitate was collected by filtration, washed with water and dried in vacuum to give 6-cyano-2-fluorophenylboronic acid pinacol ester (0.9191 g, 62%) as a white solid. The product was characterized by 1H NMR (360 MHz, DMSO-d6): δ 1.34 (12H, s), 7.55-7.59 (1H, m), 7.69-7.75 (2H, m).