A solution of 4.40 g (0.0272 mole) of 1,1'-carbonyldiimidazole and 3.46 g (0.024 mole) of N,N-diethyl-1,4-butanediamine in 400 ml of tetrahydrofuran was stirred at room temperature for 1 hr. A solution of 5.00 g (0.0220 mole) of N-[2-(phenylsulfonyl)ethyl]-2-propanamine in 50 ml of tetrahydrofuran was added, and the solution was refluxed overnight. The solvent was removed in vacuo, and the residue was dissolved in 600 ml of a 50/50 mixture of ether and methylene chloride. The organic 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 (methanol) gave 2.29 g (26.2%) of clear colorless oil:
