Compound 17 (500 mg) was taken as raw material and mixed with 6M hydrochloric acid (2.2 mL) and methanol (2.5 mL) and reacted at reflux for 3 hours. After completion of the reaction, the mixture was cooled to room temperature and the precipitate was collected by filtration. The filtrate was concentrated under vacuum and the residue was dissolved in water and neutralized with 1 M sodium hydroxide solution. A precipitate was precipitated from the neutralized solution, collected by vacuum filtration and washed sequentially with water and ether to afford the target product 5-phenyl-1H-imidazol-2-amine (18, 131 mg, 33% yield) as a light brown solid. The product was characterized by 1H NMR (DMSO-d6): δ 5.25 (2H, s), 6.96 (1H, s), 7.07 (1H, t, J = 7.5 Hz), 7.26 (2H, t, J = 7.5 Hz), 7.57 (2H, d, J = 7.5 Hz), 10.53 (1H, br s). Mass spectrometry analysis showed FAB MS m/e (M + H)+ 160; high-resolution mass spectrometry (ESI) measured 160.0875 calculated and 160.0871 measured values for C9H10N3 (M + H)+. Elemental analyses of the calculated values (C9H9N3-3H2O): C, 65.68; H, 5.88; N, 25.53; measured values: C. 65.81; H, 5.49; N, 25.19.
