[C:1]([C:4]1[CH:5]=[C:6]([O:18]S(C(F)(F)F)(=O)=O)[CH:7]=[C:8]([O:10][S:11]([C:14]([F:17])([F:16])[F:15])(=[O:13])=[O:12])[CH:9]=1)(=[O:3])[CH3:2].C(=O)([O-])[O-].[Cs+].[Cs+]>COCCOC>[C:1]([C:4]1[CH:9]=[C:8]([O:10][S:11]([C:14]([F:17])([F:15])[F:16])(=[O:13])=[O:12])[CH:7]=[C:6]([OH:18])[CH:5]=1)(=[O:3])[CH3:2]Trifluoro-methanesulfonic acid 3-acetyl-5-trifluoromethanesulfonyloxy-phenyl ester (9.9 g) was dissolved in 1,2-dimethoxyethane (80 mL), followed by addition of cesium carbonate (11.6 g). The resulting suspension was stirred at 80° C. for 3 h and then quenched with saturated solution of ammonium chloride. The solution was then extracted with diethyl ether and combined etherate extracts were washed with brine, dried over anhydrous sodium sulfate, and filtered through a silica pad. The filtrate was concentrated under reduced pressure and purified on a silica gel column using ethyl acetate and hexanes to afford 3.5 g of the title compound (52% yield). HRMS calcd for C19H7O5S1F3 [M+H]+ 285.0039, observed 285.0039.
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