[S:1]([O:8]S(C(F)(F)F)(=O)=O)([C:4]([F:7])([F:6])[F:5])(=[O:3])=[O:2].[C:16]([C:20]1[CH:25]=[CH:24][C:23](O)=[C:22]([N+:27]([O-:29])=[O:28])[CH:21]=1)([CH3:19])([CH3:18])[CH3:17].N1C=CC=CC=1.C([O-])(O)=O.[Na+]>C(Cl)Cl>[C:16]([C:20]1[CH:25]=[CH:24][C:23]([O:8][S:1]([C:4]([F:7])([F:6])[F:5])(=[O:3])=[O:2])=[C:22]([N+:27]([O-:29])=[O:28])[CH:21]=1)([CH3:19])([CH3:17])[CH3:18]
Triflic anhydride (4.14 mL, 24.6 mmol) was added dropwise to a solution of 4-tert-butyl-2-nitrophenol (4.00 g, 20.5 mmol) and pyridine (2.16 mL, 26.7 mmol) in methylene chloride (50 mL) at 0° C. The yellow solution was stirred 0.25 h at 0° C., poured onto saturated aqueous NaHCO3 and extracted with methylene chloride. The combined extracts were washed with saturated aqueous NaHCO3, dried over sodium sulfate, filtered, and concentrated in vacuo. The residue was purified by filtration through a plug of silica-gel (methylene chloride) to provide trifluoro-methanesulfonic acid 4-tert-butyl-2-nitro-phenyl ester (5.82 g, 87%) as a pale yellow oil which was utilized without further purification.
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