A mixture of 3.89 (0.024 mole) of 1,1'-carbonyldiimidazole and 2.55 g (0.022 mole) of N,N-diethylethylenediamine in 400 ml of tetrahydrofuran was stirred at room temperature for 1 hr. A solution of 5.70 g (0.0183 mole) of N-benzyl-2-phenylsulfonylethanamine in 50 ml of tetrahydrofuran was added, and the mixture was refluxed for 16 hr. The solvent was removed in vacuo, and the residue was partitioned between methylene chloride and water. The methylene chloride solution was dried over magnesium sulfate, and the solvent was removed in vacuo to give an oil. Flash chromatography on silica gel (methanol) gave 5.35 g (69.98%) of oil:
