Ethyl bromoacetate → tert-Butyl 3-(2-ethoxy-2-oxoethyl)-4-(1-ethylpropyl)-2-oxo-2,3-dihydro-1H-benzimidazole-1-carboxylate

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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; 4.94 g, 16.2 mmol) in N,N-dimethylformamide (40 mL) were added potassium carbonate (2.47 g, 17.9 mmol) and ethyl bromoacetate (1.98 mL, 17.9 mmol), and the mixture was stirred at room temperature for 3 hr. The reaction mixture was diluted with water and extracted with ethyl acetate. The organic layer was washed with brine, dried over anhydrous sodium sulfate and concentrated in vacuo. The residue was purified by silica gel column chromatography eluting with a 5-20% ethyl acetate/n-hexane gradient mixture to give the title compound (6.17 g, 15.8 mmol, 98%) as a colorless oil.

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