A mixture of 5.16 g (0.0319 mole) of 1,1'-carbonyldiimidazole and 4.16 g (0.029 mole) of N-(3-aminopropyl)piperidine in 400 ml of tetrahydrofuran was stirred at room temperature for 1 hr. A solution of 6.13 g (0.027 mole) of N-[2-(phenylsulfonyl)ethyl]-2-propanamine in 50 ml of tetrahydrofuran was added, and the mixture was refluxed for 20 hr. The solvent was removed in vacuo, and the residue was dissolved in a 60/40 mixture of ether and methylene chloride, respectively. The solution was extracted with three portions of water and was dried over magnesium sulfate. The solvent was removed in vacuo to give an oil. Flash chromatography on silica gel (chloroform and methanol, gradiently eluted with methanol up to 10% methanol) gave 2.89 g (27.1%) of oil:
