To a solution of 1,4-dichloro-5-phenylphthalazine (5.00 g, 18.2 mmol) in 1,4-dioxane (50 mL) and water (9 mL) was added ethyl 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)nicotinate (5.32 g, 27.3 mmol), and K3PO4 (7.72 g, 36.3 mmol). The contents were purged with nitrogen for 10 min. Tricyclohexylphosphonium tetrafluoroborate (0.402 g, 1.09 mmol) was added followed by Pd2(dba)3 (0.416 g, 0.454 mmol) and the reaction mixture was heated at 95° C. for 12 h. The reaction mixture was allowed to cool to ambient temperature and diluted with HCOONH4 buffer (pH˜5) solution. The reaction mixture was extracted with EtOAc (3×75 mL). The combined organic extracts were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The residue was triturated with EtOAc to afford ethyl 5-(4-hydroxy-5-phenylphthalazin-1-yl)nicotinate (3.50 g, 44.1%) as an off-white solid which is 85% pure by LC-MS. LCMS (Condition 1): retention time 2.52 min, [M+1]=372.0. 1H NMR (400 MHz, DMSO-d6) δ 1.37 (t, J=7.2 Hz, 3 H), 4.41 (q, J=7.2 Hz, 2 H), 7.33-7.42 (m, 5 H), 7.62-7.65 (m, 2 H), 7.92 (dd, J=7.6 Hz, J=8.0 Hz, 1 H), 8.49 (t, J=2.0 Hz, 1 H), 9.07 (d, J=2.0 Hz, 1 H), 9.25 (d, J=2.0 Hz, 1 H), 12.74 (br s, 1 H).
