To a stirred solution of {4-[2-(2,4-dichloro-phenoxy)-phenylsulfamoyl]-benzoylamino}-acetic acid (42 mg, 0.085 mmol) in a mixture of dichloromethane (2 mL) and dimethylformamide (0.2 mL) 1-(2-pyrrolidin-1-yl-ethyl)-piperazine (EMKA-Chemie) (18 mg, 0.1 mmol), HBTU (46 mg, 0.12 mmol) and triethylamine (60 μL, 0.4 mmol) were added. The mixture was stirred at room temperature for 24 h, then purified by column chromatography using Kieselgel 60 (0.015-0.040 mm) as adsorbent (Merck) and gradient elution starting with 100% A eluent and processing to a mixture of 70% A and 30% B eluent over a period of 15 minutes (eluent A: chloroform; eluent B: methanol containing 5% of ammonium hydroxide) to yield 45.8 mg (82%) of the title compound. MS (EI) 661.2 (MH+).
