At room temperature and under argon protection, 3,4-diaminobenzonitrile (200 mg, 1.5 mmol) was dissolved in THF (10 mL), followed by the addition of N,N'-carbonyl diimidazole (243 mg, 1.5 mmol). The reaction mixture was stirred for 16 hours. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The crude product was purified by silica gel column chromatography with 40% acetone/hexane as eluent to afford 2-oxo-2,3-dihydro-1H-benzo[d]imidazole-5-carbonitrile (60 mg, 0.37 mmol, 24% yield) as an off-white solid.1H NMR (400 MHz, DMSO-d6): δ 11.16 (br s, 1H), 11.04 (br s, 1H), 7.39 (dd, J = 8.1, 1.6 Hz, 1H), 7.30 (s, 1H), 7.06 (d, J = 8.2 Hz, 1H).
