4-(4,4,5,5-Tetramethyl-[1,3,2]dioxaborolan-2-yl)-pyrazole-1-carboxylic acid tert-butyl ester (20.7 g; 70.4 mmol; 1.0 eq.), 3-(5-Bromo-pyrimidin-2-yl)-phenylamine (intermediate 4, 17.6 g; 70.4 mmol; 1.0 eq.), bis(triphenylphosphine)palladium(II) chloride (4.94 g; 7.04 mmol; 0.10 eq.) and potassium carbonate (14.6 g; 105 mmol; 1.5 eq.) were suspended in dioxane (540 mL) and water (273 mL). The reaction mixture was then heated at 90° C. for 16 h. It was filtered through Celite and the filtrate was extracted with EtOAc. Organic phase was washed with brine, dried over magnesium sulfate, filtered and concentrated. The gum obtained was then triturated Et2O (100 mL). The resulting solid was filtered off and dried under high vacuum to give the title compound as a beige solid (14 g, 87%). 1H NMR (300 MHz, DMSO-d6) δ 13.21 (brs, 1H), 9.12 (s, 2H), 8.44 (m, 1H), 8.14 (m, 1H), 7.67 (t, J=2.0 Hz, 1H), 7.57-7.54 (m, 1H), 7.14 (t, J=7.8 Hz, 1H), 5.25 (s, 2H), 6.68 (ddd, J=7.8 Hz, 2.0 Hz, 1.0 Hz, 1H). HPLC (Condition A): Rt 1.24 min (purity 72.1%). MS (ESI+): 238.2.
