1-Bromo-3-chloropropane → 5-chloro-1-(3-chloropropyl)-1,3-dihydro-3-phenyl-2H-benzimidazol-2-one

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Reaction Steps

To a stirred solution of 7 parts of 6-chloro-1,3-dihydro-1-phenyl-2H-benzimidazol-2-one in 67.5 parts of N,N-dimethylformamide is added portionwise 1 part of a sodium hydride dispersion 78%. After stirring for 2 hours at room temperature, there are added dropwise (slowly) 4.75 parts of 1-bromo-3-chloropropane. Upon completion, stirring is continued first for two hours at room temperature and further for one hour at 60° C. The reaction mixture is poured onto water and the product is extracted with methylbenzene. The extract is dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using a mixture of trichloromethane and 5% of methanol as eluent. The pure fractions are collected and the eluent is evaporated, yielding 5-chloro-1-(3-chloropropyl)-1,3-dihydro-3-phenyl-2H-benzimidazol-2-one as a residue.

Provenance & Evidence