[F:1][C:2]1[CH:10]=[C:9]([F:11])[CH:8]=[C:7]2[C:3]=1[CH2:4][CH2:5]/[C:6]/2=[CH:12]\[C:13]([NH2:15])=[O:14].C([O:20]O)(C)(C)C.[Se](=O)=O>ClCCl.CC(C)(CC(C)C)C>[F:1][C:2]1[CH:10]=[C:9]([F:11])[CH:8]=[C:7]2[C:3]=1[CH2:4][CH:5]([OH:20])/[C:6]/2=[CH:12]\[C:13]([NH2:15])=[O:14]A suspension of (E)-2-(4,6-difluoro-1-indanylidene)acetamide (10.0 g, 0.05 mol, prepared as in Example 5 g in dichloromethane (250 mL) was added portionwise over a 10 min. period to a mixture of 70% aqueous t-butylhydroperoxide (19.8 mL, 0.15 mol, Aldrich) and selenium dioxide (3.7 g, 0.03 mol, Aldrich) in dichloromethane (500 mL) at ambient temperature. After 18h, additional t-butylhydroperoxide (10 mL of a 5.0M solution in 2,2,4-trimethylpentane, 0.05 mol, Aldrich) and selenium dioxide (1.8 g, 0.02 mol) were added and the mixture was stirred at ambient temperature. After 18h, additional t-butylhydroperoxide (10 mL of 70% aqueous solution, 0.08 mol) and selenium dioxide (3.7 g, 0.05 mol) were added and the mixture was stirred at ambient temperature for 8 days. The resulting solid was filtered off and washed with dichloromethane to give 5.85 g of crude (Z)-2-(4,6-difluoro-2-hydroxy-1-indanylidene)acetamide. After 7 days at ambient temperature a second crop of crude (Z)-2-(4,6-difluoro-2-hydroxy-1-indanylidene)acetamide was obtained from the filtrate. Column chromatography on silica gel using ethyl acetate as the eluent followed by a second column chromatography on silica gel using ethyl acetate:hexanes (3:2) as eluent and trituration of the resulting solid with pentane gave 2.38 g of (Z)-2-(4,6-difluoro-2-hydroxy-1-indanylidene)acetamide as a pink solid: m.p. 235-237° C.
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