[Br:1][C:2]1[C:7]2[CH2:8][C:9]([CH3:12])([CH3:11])[O:10][C:6]=2[CH:5]=[CH:4][CH:3]=1.S(OOS([O-])(=O)=O)([O-])(=O)=[O:14].[K+].[K+]>O.C(#N)C.O.O.O.O.O.S([O-])([O-])(=O)=O.[Cu+2]>[Br:1][C:2]1[C:7]2[C:8](=[O:14])[C:9]([CH3:12])([CH3:11])[O:10][C:6]=2[CH:5]=[CH:4][CH:3]=1Under a nitrogen atmosphere, a stirred solution of 3.0 grams (0.013 mole) 4-bromo-2,3-dihydro-2,2-dimethylbenzofuran, 10.7 grams (0.039 mole) of potassium persulfate, and 3.3 grams (0.013 mole) of copper(II) sulfate pentahydrate in 30 mL of water and 30 mL of acetonitrile was heated at reflux for one hour. After this time the reaction mixture was poured into 200 mL of water. The mixture was then extracted with one 200 mL portion of diethyl ether. The extract was dried with magnesium sulfate and filtered. The filtrate was concentrated under reduced pressure to a residual oil. The oil was subjected to column chromatography on silica gel. Elution was accomplished using 1:1 petroleum ether and methylene chloride. The product-containing fractions were combined and concentrated under reduced pressure, yielding 2.1 grams of 4-bromo-2,3-dihydro-2,2-dimethyl-3-benzofuranone. The NMR spectrum was consistent with the proposed structure. Steps A through C were repeated.
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