Phosphorus oxychloride → 1-Allyl-2,4-dichloro-7-(1-ethylpropyl)-1H-benzimidazole
Reaction equation
[CH2:1]([N:4]1[C:8]2[C:9]([CH:14]([CH2:17][CH3:18])[CH2:15][CH3:16])=[CH:10][CH:11]=[C:12]([Cl:13])[C:7]=2[NH:6][C:5]1=O)[CH:2]=[CH2:3].P(Cl)(Cl)([Cl:22])=O>C(OCC)(=O)C>[CH2:1]([N:4]1[C:8]2[C:9]([CH:14]([CH2:17][CH3:18])[CH2:15][CH3:16])=[CH:10][CH:11]=[C:12]([Cl:13])[C:7]=2[N:6]=[C:5]1[Cl:22])[CH:2]=[CH2:3]Participants
4
Procedure
A solution of 1-allyl-4-chloro-7-(1-ethylpropyl)-1,3-dihydro-2H-benzimidazol-2-one (9.80 g, 35.1 mmol) in phosphoryl chloride (35 mL) was stirred at 100° C. for 2 hr. The mixture was concentrated in vacuo to give a residue which was dissolved in ethyl acetate, washed with aqueous sodium bicarbonate and brine, dried over sodium sulfate and concentrated in vacuo. The residue was purified by flash chromatography on silica gel eluting with a 5-20% ethyl acetate/n-hexane gradient mixture. The filtrate was concentrated in vacuo to give the title compound (9.90 g, 33.3 mmol, 95%) as a colorless solid.