4-Trifluoromethyl-5-bromo-2-pyrimidinamine (16.2 g, 66.3 mmol), pinacol ester of bisboronic acid (18.5 g, 72.9 mmol), and potassium acetate (19.5 g, 199 mmol) were suspended in dioxane (300 mL) under argon protection. To this suspension was added PdCl2(dppf)CH2Cl2 adduct (2.4 g, 2.98 mmol) and the mixture was stirred at 115 °C for 4 hours. After completion of the reaction, the mixture was cooled to 50 °C and treated with ethyl acetate. The resulting suspension was filtered through Hyflo and washed with ethyl acetate. The combined filtrates were concentrated and the residue was suspended in 2N NaOH solution and stirred at room temperature for 5 minutes. Subsequently, ether and water were added and the two-phase mixture formed was filtered through Hyflo. The two phases of the filtrate were separated and the pH of the aqueous phase was adjusted to 5-6 with 4N HCl and then extracted with ethyl acetate. The organic layer was washed sequentially with water and brine, dried over anhydrous sodium sulfate, filtered and concentrated. The residue was ground in ether and hexane and filtered to give pinacol ester of 2-amino-4-trifluoromethylpyrimidine-5-boronic acid (8.33 g, 42% yield). Retention time (tR): 1.00 min (LC-MS 1); ESI-MS: 290.3 [M + H]+ (LC-MS 1).
