Water → Perfluorophenyl 1-(4-chloro-2-methoxyphenyl)phthalazine-6-sulfonate

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Reaction Steps

A round-bottom flask was charged with 6-(benzylthio)-1-(4-chloro-2-methoxyphenyl)phthalazine (369 mg, 0.939 mmol), DCM (8839 μl), acetic acid (331 μl), and water (221 μl) to give a clear, orange solution. The flask was submerged in an ice-water bath. After 5 min, 1,3-dichloro-5,5-dimethylimidazolidine-2,4-dione (379 mg, 1.925 mmol) was added in one portion. After 40 min, an additional portion of 1,3-dichloro-5,5-dimethylimidazolidine-2,4-dione (ca. 180 mg) was added. After 5 min, 2,3,4,5,6-pentafluorophenol (259 mg, 1.409 mmol) was added, then triethylamine (524 μl, 3.76 mmol) was added drop wise. The mixture was stirred for 10 min, then diluted with saturated aq. sodium bicarbonate solution, and the mixture was stirred vigorously for 5 min. The mixture was then extracted with DCM (2×). The combined organic extracts were dried over sodium sulfate, filtered, and concentrated. The residue was purified by chromatography on silica gel (40-g Redi-Sep Gold column, 0-40% EtOAc/Heptane) to give perfluorophenyl 1-(4-chloro-2-methoxyphenyl)phthalazine-6-sulfonate (234 mg, 0.453 mmol, 48.2% yield) as a cream-colored foam. m/z (ESI) 517.0 (M+H)+.

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