tert-butyl 2-bromo-3-phenylpropanoate

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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 the reaction solution was then stirred at room temperature for 30 min After renewed cooling in an ice bath the mixture was stirred while cooling in ice for 1 h extracted with ethyl acetate (3×) The combined organic phases were washed with water and saturated NaCl solution dried over magnesium sulfate concentrated in vacuo The residue was purified by chromatography on silica gel (mobile phase gradient 15-30% ethyl acetate in heptane)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 10.1 g (44.1 mmol) of 2-bromo-3-phenylpropionic acid in tert-butyl acetate (150 ml) was cooled in an ice/water bath. 0.5 ml of perchloric acid was added, and the reaction solution was stirred at room temperature overnight. The reaction solution was slowly added to a saturated aqueous sodium bicarbonate solution (200 ml) and the organic phase was separated off. The aqueous phase was extracted twice with 60 ml of ethyl acetate each time, the combined organic phases were washed with saturated aqueous sodium bicarbonate solution and dried over magnesium sulfate, and the solvent was removed in vacuo. The residue was purified by chromatography on silica gel (mobile phase gradient 20% acetic acid in cyclohexane). Yield: 6.76 g (54%) of colorless oil was cooled in an ice/water bath the organic phase was separated off The aqueous phase was extracted twice with 60 ml of ethyl acetate each time the combined organic phases were washed with saturated aqueous sodium bicarbonate solution dried over magnesium sulfate the solvent was removed in vacuo The residue was purified by chromatography on silica gel (mobile phase gradient 20% acetic acid in cyclohexane)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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 the reaction solution was then stirred at room temperature for 30 min After renewed cooling in an ice bath the mixture was stirred while cooling in ice for 1 h extracted with ethyl acetate (3×) The combined organic phases were washed with water and saturated NaCl solution dried over magnesium sulfate concentrated in vacuo The residue was purified by chromatography on silica gel (mobile phase gradient 15-30% ethyl acetate in heptane)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 10.1 g (44.1 mmol) of 2-bromo-3-phenylpropionic acid in tert-butyl acetate (150 ml) was cooled in an ice/water bath. 0.5 ml of perchloric acid was added, and the reaction solution was stirred at room temperature overnight. The reaction solution was slowly added to a saturated aqueous sodium bicarbonate solution (200 ml) and the organic phase was separated off. The aqueous phase was extracted twice with 60 ml of ethyl acetate each time, the combined organic phases were washed with saturated aqueous sodium bicarbonate solution and dried over magnesium sulfate, and the solvent was removed in vacuo. The residue was purified by chromatography on silica gel (mobile phase gradient 20% acetic acid in cyclohexane). Yield: 6.76 g (54%) of colorless oil was cooled in an ice/water bath the organic phase was separated off The aqueous phase was extracted twice with 60 ml of ethyl acetate each time the combined organic phases were washed with saturated aqueous sodium bicarbonate solution dried over magnesium sulfate the solvent was removed in vacuo The residue was purified by chromatography on silica gel (mobile phase gradient 20% acetic acid in cyclohexane)