The reaction of ethyl 4-piperidone-1-carboxylate (I) with hydroxylamine gives the corresponding oxime (II), which by catalytic hydrogenation over Raney-Ni yields ethyl 4-aminopiperidine-1-carboxylate (III). The condensation of (III) with 2,5-dichloronitrobenzene (IV) by means of K2CO3 and KI in cyclohexanol at 160 C affords ethyl 4-(4-chloro-2-nitroanilino)-1-piperidinecarboxylate (V), which is reduced with H2 over Raney-Ni to the corresponding amino compound (VI). The cyclization of (VI) with urea (VII) at 170-80 C gives ethyl 4-(1,3-dihydro-2-oxo-5-chloro-2H-benzimidazol-1-yl)-1-piperidinecarboxylate (VIII), which is hydrolyzed and decarboxylated by treatment with KOH in refluxing propanol - water giving 1,3-dihydro-1-(4-piperidinyl)-5-chloro-2H-benzimidazol-2-one (IX). Finally this compound is condensed with 4,4-bis(p-fluorophenyl)butyl chloride (X) by means of NaHCO3 in refluxing ethanol.

The reaction of ethyl 4-piperidone-1-carboxylate (I) with hydroxylamine gives the corresponding oxime (II), which by catalytic hydrogenation over Raney-Ni yields ethyl 4-aminopiperidine-1-carboxylate (III). The condensation of (III) with 2,5-dichloronitrobenzene (IV) by means of K2CO3 and KI in cyclohexanol at 160 C affords ethyl 4-(4-chloro-2-nitroanilino)-1-piperidinecarboxylate (V), which is reduced with H2 over Raney-Ni to the corresponding amino compound (VI). The cyclization of (VI) with urea (VII) at 170-80 C gives ethyl 4-(1,3-dihydro-2-oxo-5-chloro-2H-benzimidazol-1-yl)-1-piperidinecarboxylate (VIII), which is hydrolyzed and decarboxylated by treatment with KOH in refluxing propanol - water giving 1,3-dihydro-1-(4-piperidinyl)-5-chloro-2H-benzimidazol-2-one (IX). Finally this compound is condensed with 4,4-bis(p-fluorophenyl)butyl chloride (X) by means of NaHCO3 in refluxing ethanol.