The general procedure for the synthesis of 2-phenyl-5-azolone from equine uric acid was as follows: equine uric acid (5.0 g, 27.9 mmol) and EDCI-HCl (7.0 g, 36.3 mmol) were dissolved in dichloromethane (50 mL) and stirred for 45 min at room temperature under nitrogen protection. Upon completion of the reaction, the reaction was quenched with water. The organic layer was separated and washed twice with water and once with brine sequentially, then dried with anhydrous magnesium sulfate. After filtration, the filtrate was concentrated in vacuum to afford 2-phenyl-5-azolone as an off-white solid (4.1 g, 91% yield), which could be used in the next reaction without further purification. The nuclear magnetic resonance hydrogen spectrum (1H NMR, 600 MHz, CDCl3) data of the product were as follows: δ 7.96 (dd, J = 5.2, 3.3 Hz, 2H), 7.55 (m, 1H), 7.46 (m, 2H), 4.38 (s, 2H). Nuclear magnetic resonance carbon spectroscopy (13C NMR, 151 MHz, CDCl3) data were as follows: δ 176.00, 163.54, 132.87, 129.09, 128.88, 128.66, 127.86, 125.94, 77.37, 77.16, 76.95, 55.04.
