Phosphorus oxychloride → 2,4-Dichloro-1H-benzo[d]imidazole
Reaction equation
[Cl:1][C:2]1[C:10]2[NH:9][C:8](=O)[NH:7][C:6]=2[CH:5]=[CH:4][CH:3]=1.P(Cl)(Cl)([Cl:14])=O>>[Cl:14][C:8]1[NH:7][C:6]2[CH:5]=[CH:4][CH:3]=[C:2]([Cl:1])[C:10]=2[N:9]=1Participants
3
Conditions
- Temperature
- 80 °C
Procedure
Phosphorus oxychloride (10 mL) was added to 4-chloro-1,3-dihydro-benzoimidazol-2-one (0.750 g, 4.45 mmol), and the mixture heated to 80° C. for 48 h. The mixture was cooled to 23° C. and POCl3 removed under reduced pressure. The residue was cooled to 0° C., and cold saturated aqueous NaHCO3 (20 mL) was added cautiously. After stirring at 23° C. for 15 min, the mixture was sonicated and the resulting residue was filtered to yield the titled compound (0.760 g, 92%), which was used in the next step without further purification. MS (ESI/CI): mass calcd. for C7H5Cl2N2, 186.0; m/z found, 187.0 [M+H]+. 1H NMR (500 MHz, DMSO-d6): 13.68 (s, 1H), 7.51-7.42 (m, 1H), 7.32-7.25 (m, 1H), 7.22 (m, 1H).