Phosphorus oxychloride → Isopropyl [2,4-dichloro-7-(1-ethylpropyl)-1H-benzimidazol-1-yl]acetate

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Reaction Conditions

Reaction Steps

A mixture of isopropyl [4-chloro-7-(1-ethylpropyl)-2-oxo-2,3-dihydro-1H-benzimidazol-1-yl]acetate (14.5 g, 42.8 mmol) and phosphorus oxychloride (60 mL) was stirred at 100° C. for 3 days. After cooling, phosphorus oxychloride was evaporated in vacuo. The residue was poured into ice-cold saturated aqueous sodium hydrogen carbonate and extracted with ethyl acetate (×2). The combined organic layer was washed with water and brine, dried over anhydrous sodium sulfate and concentrated in vacuo. The residue was purified by silica gel column chromatography eluting with a 5-15% ethyl acetate/n-hexane gradient mixture to give the title compound (14.1 g, 39.5 mmol, 92%) as an oil.

Provenance & Evidence