[F:1][C:2]([Si](C)(C)C)([F:4])[F:3].[Cl:9][C:10]1[CH:15]=[C:14]([O:16][CH3:17])[CH:13]=[CH:12][C:11]=1[CH:18]([CH3:32])[C:19]([C:21]1[CH:22]=[CH:23][C:24]2[O:28][C:27](=[O:29])[N:26]([CH3:30])[C:25]=2[CH:31]=1)=[O:20].O.O.O.[F-].C([N+](CCCC)(CCCC)CCCC)CCC.[F-].C([N+](CCCC)(CCCC)CCCC)CCC>C1COCC1>[Cl:9][C:10]1[CH:15]=[C:14]([O:16][CH3:17])[CH:13]=[CH:12][C:11]=1[CH:18]([CH3:32])[C:19]([C:21]1[CH:22]=[CH:23][C:24]2[O:28][C:27](=[O:29])[N:26]([CH3:30])[C:25]=2[CH:31]=1)([OH:20])[C:2]([F:4])([F:3])[F:1]Trifluoromethyltrimethylsilane (2M in THF, 6.33 mL) was added at 0° C. to a solution of 5-[2-(2-chloro-4-methoxy-phenyl)-propionyl]-3-methyl-3H-benzooxazol-2-one (1.99 g) in THF (30 mL) followed by the addition of tetrabutylammonium fluoride trihydrate (363 mg). Stirring was continued for 2.5 hours at 0° C. More tetrabutylammonium fluoride (1M in THF, 4.60 mL) was added to the reaction mixture and stirring was continued for 30 minutes at r.t. The reaction mixture was poured into ice/water and extracted two times with ethyl acetate. The combined organic layers were washed with brine, dried over Na2SO4, filtered and the solvent was evaporated. The residue was purified by flash chromatography (silica gel, CH2Cl2:MeOH=100:0 to 99:1) to give the title compound as a colorless foam (2.0 g, 80%). MS (m/e)=416.3 [M+H+].
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