To a solution of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-hydroxy-2-phenylethyl)amide (0.517 g, 1.03 mmol) in dichloromethane (10 mL), 1,1,1-triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one (0.53 g) was added in one portion under stirring in a cold water bath. After stirred in a cold water bath for 15 minutes and then at ambient temperature for 2 hours, the reaction mixture was diluted with diethyl ether (20 mL). The mixture was poured into a solution of sodium thiosulfate (1.176 g, 7.44 mmol) in saturated aqueous sodium biocarbonate (29 mL). The mixture was extracted with ethyl acetate (100 mL). The organic layer was washed with saturated aqueous NaHCO3 (2×15 mL) and water (2×15 mL). The combined aqueous washes were then extracted with ethyl acetate (2×80 mL). The combined organic phases were dried over Na2SO4 and filtered, the solvent was then removed in vacuo. The crude product was purified by column chromatography, which was sequentially eluted with hexane:ethyl acetate (1:1), hexane:ethyl acetate (1:2) and pure ethyl acetate. The product was obtained as a white powder (0.261 g, 51% yield). m.p. 196-198° C. 1H NMR (300 MHz, CDCl3) δ 8.72, 7.97-8.06, 7.74, 7.47-7.66, 7.36, 6.99, 4.96, 4.02-4.11, 3.70-3.92, 3.27-3.42. 13C NMR (CDCl3) δ 193.4, 167.7, 163.4, 160.0, 145.1, 134.6, 134.2, 134.0, 132.4, 129.6, 128.9, 128.0, 127.2, 126.9, 126.8, 112.3, 46.4, 44.7, 44.4, 41.3. MS (ES+) m/z 498 (M+1).
