Procedure for the synthesis of imidazo[1,2-c]pyrimidin-5(6H)-one (13): 50% aqueous chloroacetaldehyde (0.686 mL, 5.40 mmol) was added to a stirred solution of 6-aminopyrimidin-2(1H)-one (500 mg, 4.50 mmol) in N,N-dimethylformamide (DMF, 10 mL). The reaction mixture was stirred at 70 °C for 16 hours. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The residue was washed with ethanol and ether to afford the target compound 13 as a light brown powder (320 mg, 53% yield). Thin layer chromatography (TLC) analysis showed Rf = 0.47 (unfolding agent: ethyl acetate/methanol, 4:1). The melting point of the product was 281-282 °C. Nuclear magnetic resonance hydrogen spectrum (1H NMR, 400 MHz, [D6]DMSO): δ = 6.62 (d, 1H, 3J = 7.6 Hz), 7.28 (d, 1H, 3J = 7.6 Hz), 7.41 (d, 1H, 3J = 1.2 Hz), 7.80 (d, 1H, 3J = 1.2 Hz), 11.6 (bs, 1H). Nuclear magnetic resonance carbon spectrum (13C NMR, 100 MHz, [D6]DMSO): δ = 97.7, 112.2, 129.4, 132.3, 145.9, 146.4. infrared spectrum (IR, KBr): ν = 3451, 3121, 3096, 1718, 1630, 1547, 1290, 1252, 1111 cm- 1. mass spectrum (ESI-MS): m/z 135.8 [M + H]+.
