Phosphorus oxychloride → 2,4-Dichloro-7-(1-ethylpropyl)-1-methyl-1H-benzimidazole
Reaction equation
[Cl:1][C:2]1[C:10]2[NH:9][C:8](=O)[N:7]([CH3:12])[C:6]=2[C:5]([CH:13]([CH2:16][CH3:17])[CH2:14][CH3:15])=[CH:4][CH:3]=1.P(Cl)(Cl)([Cl:20])=O>>[Cl:20][C:8]1[N:7]([CH3:12])[C:6]2[C:5]([CH:13]([CH2:16][CH3:17])[CH2:14][CH3:15])=[CH:4][CH:3]=[C:2]([Cl:1])[C:10]=2[N:9]=1Participants
3
Conditions
- Temperature
- 90 °C
Procedure
A mixture of 4-chloro-7-(1-ethylpropyl)-1-methyl-1,3-dihydro-2H-benzimidazol-2-one (1.17 g, 4.63 mmol) in phosphorous oxychloride (28 g) was stirred at 90° C. for 3 h. The reaction was allowed to cool to room temperature and concentrated in vacuo. The residue was dissolved in ethyl acetate, washed with aqueous sodium bicarbonate and brine. The organic layer was dried over magnesium sulfate, filtered, and concentrated in vacuo. The residue was subjected to chromatography on silica gel (n-hexane/ethyl acetate=10:1-1:1) and crystallized from ethyl acetate-hexane to afford the title compound as colorless crystals (1.03 g, 82%). mp 94-95° C.