F[C:2]1[CH:7]=[CH:6][C:5]([C:8](=[O:20])[CH2:9][CH2:10][C:11](=[O:19])[CH2:12][CH2:13][C:14]([O:16][CH2:17][CH3:18])=[O:15])=[CH:4][CH:3]=1.[Na].[CH3:22][S:23]([OH:25])=[O:24]>CN(C=O)C>[CH3:22][S:23]([C:2]1[CH:7]=[CH:6][C:5]([C:8](=[O:20])[CH2:9][CH2:10][C:11](=[O:19])[CH2:12][CH2:13][C:14]([O:16][CH2:17][CH3:18])=[O:15])=[CH:4][CH:3]=1)(=[O:25])=[O:24]To a solution of ethyl 4-fluoro-γ,ζ-dioxobenzeneheptanoate (Step 2) (870 mg, 3.1 mmol) in DMF (25 ml), methanesulfinic acid sodium (1.27 g, 12.4 mmol) was added. The reaction mixture was heated at 130-35° C. for 30 hours. After cooling, the solvent was removed under reduced pressure and the reaction mixture was diluted with water. The material was extracted with ethyl acetate and washed with brine. After drying (MgSO4), filtration and concentration, the crude dark brown solid (840 mg) was purified by chromatography (silica gel, hexane/ethyl acetate, 1/1) to give the sulfone (270 mg, 26%) as a white solid: mp (DSC) 97° C. Anal Calc'd. for C16H20SO6 : C, 56.46; H, 5.92; S, 9.42. Found: C, 56.56; H, 6.10; S, 9.62.
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