To a solution of α-cyclohexylmethyl-2-piperidinobenzylamine (1.13 g, 3.96 mmol) in acetonitrile (11 ml) are added, successively, 3-ethoxy-4-ethoxycarbonyl-phenyl acetic acid (1 g, 3.96 mmol), of triphenylphosphine (1.25 g, 4.76 mmol), triethylamine (1.11 ml, 7.92 mmol) and carbon tetrachloride (0.38 ml, 3.96 mmol) and the mixture is stirred for 15 hours at ambient temperature. It is then concentrated by evaporation in vacuo and partitioned between ethyl acetate and water. The organic extract is dried and filtered and concentrated by evaporation in vacuo. The evaporation residue is purified by column chromatography on silica gel (toluene/acetone=10/1).
