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1.20 g (4.47 mmol) of tert-butyl 5-chloro-2-oxo-2,3-dihydrobenzimidazole-1-carboxylate (Via) were dissolved in dry DMF (15 ml) in a heat-dried flask under a nitrogen atmosphere. 187 mg (4.69 mmol) of sodium hydride (60% suspension in mineral oil) were added while stirring at 0° C., and the reaction solution was then stirred at room temperature for 30 min. After renewed cooling in an ice bath, 1.40 g (4.91 mmol) of tert-butyl 2-bromo-3-phenylpropionate were added, and the mixture was stirred while cooling in ice for 1 h and then at room temperature for 2 h. The reaction solution was diluted with ethyl acetate, mixed with 10% aqueous ammonium chloride solution and then extracted with ethyl acetate (3×). The combined organic phases were washed with water and saturated NaCl solution, dried over magnesium sulfate and concentrated in vacuo. The residue was purified by chromatography on silica gel (mobile phase gradient 15-30% ethyl acetate in heptane). Yield: 1.3 g (62%) of colorless oil

1. stirringthe reaction solution was then stirred at room temperature for 30 min
2. temperatureAfter renewed cooling in an ice bath
3. stirringthe mixture was stirred
4. temperaturewhile cooling in ice for 1 h
5. extractionextracted with ethyl acetate (3×)
6. washThe combined organic phases were washed with water and saturated NaCl solution
7. dry with materialdried over magnesium sulfate
8. concentrationconcentrated in vacuo
9. customThe residue was purified by chromatography on silica gel (mobile phase gradient 15-30% ethyl acetate in heptane)