3-(5-Chloro-2-methoxy-benzenesulfonylamino)-N-[4-(N-hydroxycarbamimidoyl)-phenyl]-benzamide (110 mg, 0.23 mmol) was diluted in acetonitrile (2 ml) under argon. 1,1′-Thiocarbonyldiimidazole (TCDI) (68 mg, 0.38 mmol, 1.65 equiv.) was then added, followed by 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) (114 mg, 3.95 equiv.). The mixture was stirred at room temperature for 6 hours, then the solvents were evaporated. The residue was diluted with water and the pH was adjusted to 4 with HCl 1N. The aqueous phase was extracted with ethyl acetate, and the organic phase evaporated. The residue was dissolved in NaOH 1N, and washed with ether. The aqueous solution was adjusted to pH 4 with HCl 1N and then extracted with ethyl acetate. The organic phase was dried over sodium sulfate and evaporated. Purification via flash chromatography (dichloromethane/methanol) yielded the title compound as a light yellow solid (24 mg, 20%), MS (ISP): m/e=515.1 (M−H).
