Using 2-amino-4-methyl-5-bromopyrimidine (5.0 g, 26 mmol) and pinacol ester of bisboronic acid (7.43 g, 29.2 mmol) as raw materials, the two were mixed with potassium acetate (7.83 g, 79.8 mmol) in dioxane (140 mL) under nitrogen protection, and stirred for 20 minutes. Subsequently, 1,1'-bis(diphenylphosphino)ferrocene palladium(II) chloride dichloromethane adduct (1.08 g, 1.33 mmol) was added to the reaction mixture. The reaction mixture was heated to 115 °C under nitrogen protection and kept for 18 hours. After completion of the reaction, the mixture was cooled, EtOAc was added, sonicated and filtered. The solid was washed with additional EtOAc. The organic extracts were combined, washed with water, dried over MgSO4, filtered and concentrated. The crude product was purified by column chromatography using a 20-100% EtOAc/hexane gradient elution to give 4.5 g 2-amino-4-methylpyrimidine-5-boronic acid pinacol ester (yield: 74%). The structure of the product was confirmed by 1H-NMR (DMSO, 400 MHz) and mass spectrometry (ESI): 1H-NMR δ 8.28 (s, 1H), 6.86 (br s, 2H), 2.35 (s, 3H), 1.25 (s, 12H); MS (ESI) m/e 236.15 (M + H+), 154.07.
