Phosphorus oxybromide → 2-Bromo-7-(1-ethylpropyl)-1-methyl-1H-benzimidazole

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Reaction Steps

A mixture of 7-(1-ethylpropyl)-1-methyl-1,3-dihydro-2H-benzimidazol-2-one (2.10 g, 10.0 mmol), phosphoric tribromide (5.73 g, 20.0 mmol) and toluene (10 mL) was heated under reflux for 16 hr. The reaction mixture was concentrated in vacuo. The residue was dissolved in saturated sodium hydrogen carbonate solution and ethyl acetate, and extracted. The organics were dried over anhydrous magnesium sulfate, filtered, and concentrated in vacuo. The residue was purified by silica gel column chromatography eluting with a 10-50% ethyl acetate/n-hexane gradient mixture to give the title compound (312 mg, 1.11 mmol, 11%) as colorless oil.

Provenance & Evidence