[CH3:1][C:2]([CH3:4])=[O:3].[F:5][C:6]1([F:17])[C:15]2C(=[CH:11][CH:12]=[C:13]([F:16])[CH:14]=2)CC[CH2:7]1.[Mn]([O-])(=O)(=O)=O.[K+]>O.O.O.O.O.O.O.S([O-])([O-])(=O)=O.[Mg+2]>[F:5][C:6]1([F:17])[C:15]2[C:4](=[CH:11][CH:12]=[C:13]([F:16])[CH:14]=2)[C:2](=[O:3])[CH2:1][CH2:7]1An acetone solution (278 mL) of trifluoride 52 (3.11 g, 16.7 mmol) was diluted with an aqueous solution (209 mL) of magnesium sulfate heptahydrate (12.4 g). The solution was then cooled to 0° C. and potassium permanganate (7.92 g) was added portion wise over 1 hour. The reaction was allowed to warm to ambient temperature over 16 h. The reaction was quenched by addition of an aqueous 50% citric acid solution (100 mL) followed by sodium thiosulfate (5.21 g). The dark purple reaction became colorless and biphasic. The volatiles were removed and the aqueous was then extracted with dichloromethane (300 mL). The organic phase was separated, dried over sodium sulfate and concentrated. The product was purified by silica gel with a gradient heptanes/ethyl acetate eluent system on an ISCO companion to give the desired product as a yellow oil (2.09 g, 10.4 mmol, 63% yield). 1H NMR (400 MHz, CDCl3) δ: 8.10 (t, J=8 Hz, 1H), 7.44 (d, J=4 Hz, 1H), 7.26 (m, 1H), 2.91 (t, J=4 Hz, 2H), 2.66 (m, 2H).
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