To a solution of [1-(3,5-dichloro-benzyl)-1H-imidazol-2-ylmethyl]-(3-fluoro-benzyl)-amine (146 mg, 0.4 mmol) in THF (1 mL) at −78° C. was added dropwise a solution of n-BuLi in hexane (0.19 mL, 0.44 mmol) and the mixture stirred at −78° C. for 30 min. A solution of 4-(2-Chloro-ethyl)-piperazine-1-carboxylic acid tert-butyl ester (116 mg, 0.46 mmol) in THF (1 mL) was then added dropwise and the mixture allowed to warm to ambient temperature before stirring for an additional 24 h. The reaction was quenched with water (10 mL) and extracted with CH2Cl2 (2×40 mL). The combined CH2Cl2 extracts were dried over Na2SO4 and concentrated in vacuo. The residue was purified by column chromatography (silica gel, 20:1 CH2Cl2/MeOH) to provide 4-{2-[[1-(3,5-dichloro-benzyl)-1H-imidazol-2-ylmethyl]-(3-fluoro-benzyl)-amino]-ethyl}-piperazine-1-carboxylic acid tert-butyl ester (102 mg, 44%) as a colorless viscous oil: ESI MS m/z 576 [C29H36Cl2FN5O2+H]+.
