Potassium Iodide → 6-chloro-1-{3-[4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl]propyl}-1,3-dihydro-2H-benzimidazol-2-one

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Reaction Steps

A mixture of 5.6 parts of 6-chloro-1-(3-chloropropyl)-1,3-dihydro-2H-benzimidazol-2-one, 4.2 parts of 4-(4-chlorophenyl)-4-piperidinol, 6.4 parts of sodium carbonate, 0.2 parts of potassium iodide and 200 parts of 4-methyl-2-pentanone is stirred and refluxed overnight with water-separator. After cooling, water is added and the layers are separated. The 4-methyl-2-pentanone-phase is dried, filtered and evaporated. The oily residue is purified by column-chromatography over silica gel using a mixture of trichloromethane and 10% of methanol as eluent. The pure fractions are collected and the eluent is evaporated. The solid residue is crystallized from 4-methyl-2-pentanone, yielding 3.5 parts of 6-chloro-1-{3-[4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl]propyl}-1,3-dihydro-2H-benzimidazol-2-one; mp. 180.6° C.

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