A mixture of 3-bromo-6-fluoro-2-methylaniline (500 mg, 2.45 mmol), pinacol ester of bis(boronic acid) (747.8 mg, 2.95 mmol) and potassium acetate (721.5 mg, 7.35 mmol) was dissolved in 1,4-dioxane (5 mL) under nitrogen protection and nitrogen was bubbled for 5 minutes. Subsequently 1,1'-bis(diphenylphosphino)ferrocene palladium(II) dichloride dichloromethane adduct (130 mg, 0.160 mmol) was added and nitrogen was again bubbled in. The reaction mixture was heated under reflux conditions for 4.5 hours. The progress of the reaction was monitored by TLC (unfolding agent ratio 3:2 isohexane/dichloromethane) to confirm complete consumption of the feedstock.LCMS analysis showed a retention time of the main peak of 1.29 min, which accounted for 86% of the total area, and a molecular weight of 252.5 (M+H). Upon completion of the reaction, it was cooled to room temperature and excess 1,4-dioxane was removed by distillation under reduced pressure. The residue was partitioned between dichloromethane and deionized water and the mixture was filtered through a hydrophobic glass stock. The organic phase was collected, concentrated under reduced pressure and purified by fast column chromatography (elution gradient: 0-100% ethyl acetate/isohexane, elution time 45 min). The fractions containing the target product were combined and concentrated under reduced pressure to afford 6-fluoro-2-methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline, which was initially in the form of an oil, and solidified to a white solid in 76% yield after standing overnight.1H NMR (DMSO-d6) δ : 6.86 (m, 2H), 4.76 (bs, 2H). 2.29 (s, 3H), 1.28 (s, 12H).
