General procedure for the synthesis of 5-methoxy-1H-benzo[d]imidazol-2(3H)-one from 1,2-diamino-4-iodobenzene: Preparation of intermediate 37: Intermediate 36 (7.3 g, 30.6 mmol) was dissolved in N,N-dimethylformamide (DMF, 70 mL). Anhydrous potassium carbonate (K2CO3, 4.7 g, 33.7 mmol) was added to this solution and the mixture was heated to reflux (130 °C) for 5 h of reaction. After completion of the reaction, the solvent was removed by distillation under reduced pressure, the residue was poured into ice water and the aqueous phase was extracted with ethyl acetate (EtOAc). The organic layers were combined, dried over anhydrous sodium sulfate (Na2SO4) and concentrated under reduced pressure. The resulting yellow solid was recrystallized from ethanol (EtOH) to give 5-methoxy-1H-benzo[d]imidazol-2(3H)-one (Intermediate 37, 3.6 g, 72% yield) as a yellow solid with a melting point of 249-251 °C.
