[Br:1]([O-])(=O)=O.[Na+].[CH3:6][C:7]1[O:8][C:9]([C:16]2[CH:21]=[CH:20][C:19]([C:22]([F:25])([F:24])[F:23])=[CH:18][CH:17]=2)=[CH:10][C:11]=1[C:12]([O:14][CH3:15])=[O:13].S([O-])(O)=O.[Na+].C(OCC)C>O.C1CCCCC1>[Br:1][CH2:6][C:7]1[O:8][C:9]([C:16]2[CH:21]=[CH:20][C:19]([C:22]([F:23])([F:25])[F:24])=[CH:18][CH:17]=2)=[CH:10][C:11]=1[C:12]([O:14][CH3:15])=[O:13]A solution of sodium bromate (8.14 g) in water (27 ml) was treated with a suspension of methyl 2-methyl-5-[4-(trifluoromethyl)phenyl]-3-furoate (intermediate 23, 5.12 g) in cyclohexane (36 ml). The system was cooled to <10° C. in ice/water bath and treated with a solution of sodium hydrogen sulfite (9.4 g) in water (54 ml) in a drop-wise manner over 30 minutes. The reaction was allowed to warm up to 10° C. for 2 hours and then poured into diethylether (400 ml) and washed with fresh water. The organic layer was washed with 10% sodium thiosulfite solution and dried over magnesium sulfate. The crude product isolated by evaporation, was pre-adsorbed onto silica and purified by flash column chromatography using 39:1 cyclohexane:ethyl acetate as eluent to give the title compound as a white powder.
불러오는 중…
