To a methylene chloride solution (700 ml) of 2-ethylpiperazine hydrochloride (5.00 g) were added 5-chloro -1-phenylsulfonylindol-2-sulfonyl chloride (7.14 g) and triethylamine (11.16 ml) and the resulting mixture was stirred at room temperature for 3 hours. Distilled water and methylene chloride were added and the water layer was extracted three times. The organic layers were combined, dried over anhydrous sodium sulfate and distilled under reduced pressure to remove the solvent. The residue was purified by chromatography on a silica gel column (methanol:methylene chloride=1:100), whereby the title compound (5.86 g) was obtained as a pale yellow oil.
