To a solution of (1RS,2SR)-5-methyl-1-phenyl-2-(3-piperidinopropylamino)hexan-1-ol (1.66 g, 5 mmol) in toluene (25 ml) was added sodium hydride (0.14 g, 6 mmol) and the mixture was refluxed for 1 hour. To the reaction mixture was added methyl tosylate (1.12 g, 6 mmol) and the resulting mixture was refluxed for further 1 hour. After being cooled, the mixture was washed twice with water and once with brine, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The residue was purified by neutral alumina column chromatography (alumina: 40 g, eluent: chloroform) to give 1.1 g of oily matter. To a solution of the matter in acetone (20 ml) was added concentrated hydrochloric acid (0.1 ml) and the mixture was concentrated under reduced pressure. The residue was recrystallized from acetone (10 ml)-ethanol (0.2 ml) to obtain 0.45 g of the title compound as white crystals (yield: 21%).
