A solution of 1,1'-carbonyldiimidazole (6.00 g, 0.037 mole) and N,N-diethylethylenediamine (4.00 g, 0.034 mole) was stirred at room temperature for 2 hours in 200 ml of tetrahydrofuran. A solution of N-(1-methylethyl)-4-(phenylsulfonyl]-1-butylamine (free base 7.99 g, 0.0313 mole) in 100 ml of tetrahydrofuran was added and the solution was heated overnight at reflux. The reaction was stripped to dryness and the residue dissolved in chloroform. The chloroform was extracted with water, dried (sodium sulfate), filtered, and removed in vacuo. A dark brown oil was obtained upon removal of chloroform. This oil was subjected to flash chromatography on Silica Gel using 0.1N ammonium hydroxide-methanol for elution. This chromatography furnished 5.37 g (42.2% yield) of clear oil after drying in vacuo 18 hours at 60° C.
