[CH2:1]([N:4]1[C:8]2[C:9]([CH:13]([CH2:16][CH3:17])[CH2:14][CH3:15])=[CH:10][CH:11]=[CH:12][C:7]=2[NH:6][C:5]1=[O:18])[CH:2]=[CH2:3].[Cl:19]N1C(=O)CCC1=O>C1(C)C=CC=CC=1.[Cl-].[Zr+4].[Cl-].[Cl-].[Cl-]>[CH2:1]([N:4]1[C:8]2[C:9]([CH:13]([CH2:16][CH3:17])[CH2:14][CH3:15])=[CH:10][CH:11]=[C:12]([Cl:19])[C:7]=2[NH:6][C:5]1=[O:18])[CH:2]=[CH2:3]To a mixture of 1-allyl-7-(1-ethylpropyl)-1,3-dihydro-2H-benzimidazol-2-one (22.0 g, 89.8 mmol) and zirconium chloride (1.05 g, 4.49 mmol) in toluene (300 mL) was added N-chlorosuccinimide (12.4 g, 92.5 g) portionwise at 0° C. After stirring for 15 hr, the mixture was concentrated in vacuo to give a residue which was partitioned in aqueous sodium bicarbonate and ethyl acetate. The aqueous layer was extracted with ethyl acetate. Combined organic layer was washed with aqueous sodium bicarbonate and brine, dried over anhydrous sodium sulfate and concentrated in vacuo. The residue was dissolved in hot ethyl acetate. n-Hexane was then added and the solution was cooled down. Resulting precipitate was collected by filtration to afford the title compound (9.60 g, 34.4 mmol, 38%) as a colorless solid.
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