A mixture of 283 mg of 1-[bis(4-fluorophenyl)methyl]-3,3-dimethylpiperazine and 204 mg of N-(3-fluorophenyl)chloroacetamide was dissolved in 20 ml of a 1:1 by volume mixture of tetrahydrofuran and N,N-dimethylformamide, and 1 g of anhydrous potassium carbonate was added to the resulting solution. The reaction mixture was then stirred at 80° C. for 16 hours, after which ethyl acetate was added, and the organic layer was separated. The organic layer was washed with water and dried over anhydrous magnesium sulfate. The solvent was then removed by evaporation under reduced pressure. The residue was subjected to silica gel thin layer chromatography using a 2:1 by volume mixture of cyclohexane and ethyl acetate as the developing solvent, to give a purified 1-[bis(4-fluorophenyl)methyl]-4-[(3-fluorophenyl)carbamoylmethyl]-3,3-dimethylpiperazine.
