Water → 1-Allyl-7-(1-ethylpropyl)-1,3-dihydro-2H-benzimidazol-2-one

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Reaction Steps

To a solution of tert-butyl 4-(1-ethylpropyl)-2-oxo-2,3-dihydro-1H-benzimidazole-1-carboxylate (Reference Example 7; 30.4 g, 100 mmol) in N,N-dimethylformamide (300 mL) was added sodium hydride (60% dispersion in mineral oil, 4.80 g, 120 mmol) portionwise at 0° C. After stirring for 30 min, allyl bromide (10.4 mL, 120 mmol) was added dropwise. The mixture was warmed to room temperature and stirred for 16 hours. Water was added to the mixture, which was extracted with ethyl acetate. Organic layer was washed with water and brine, dried over anhydrous magnesium sulfate and concentrated in vacuo. The residue was dissolved in ethyl acetate (300 mL) and 4N hydrogen chloride solution in ethyl acetate (300 mL) was added. After stirring for 70 hr, the mixture was concentrated in vacuo to give a solid which was washed with n-hexane to afford the title compound (22.2 g, 90.6 mmol, 91%) as a colorless solid.

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