A mixture of (2R)-1-[3,5-bis(trifluoromethyl)benzoyl]-2-(3,4-dimethylbenzyl)-4-(4-chloro-2-butynyl)piperazine (200 mg), 1-cyclohexylpiperazine (63 mg) and powdered potassium carbonate (210 mg) in dry N,N-dimethylformamide (2 ml) was stirred for 12 hours at room temperature. Additional 1-cyclohexylpiperazine (25 mg) was added and after 2 hours the reaction mixture was poured into water (20 ml) and extracted with ethyl acetate. The organic layer was washed with brine and dried over magnesium sulfate. After evaporation of the solvent, the resulting residue was purified by column chromatography on silica gel using a mixture of dichloromethane and methanol (30:1). The obtained product was dissolved in ethyl acetate and treated with 4N hydrogen chloride in ethyl acetate solution (0.6 ml) to give (2R)-1-[3,5-bis(trifluoromethyl)benzoyl]-2-(3,4-dimethylbenzyl)-4-[4-(4-cyclohexylpiperazin-1-yl)-2-butynyl]piperazine trihydrochloride (220 mg).
