[F:1][C:2]1[CH:10]=[CH:9][CH:8]=[C:7]2[C:3]=1[C:4]([CH3:13])([CH3:12])[C:5](=[O:11])[NH:6]2.[N+:14]([O-])([OH:16])=[O:15]>S(=O)(=O)(O)O>[F:1][C:2]1[C:10]([N+:14]([O-:16])=[O:15])=[CH:9][CH:8]=[C:7]2[C:3]=1[C:4]([CH3:13])([CH3:12])[C:5](=[O:11])[NH:6]2To a solution of 4-fluoro-3,3-dimethyl-1,3-dihydro-2H-indol-2-one (4.1 g) in concentrated sulfuric acid (60 mL) was added dropwise a mixture of fuming nitric acid (0.99 mL) and concentrated sulfuric acid (10 mL) over 30 min at −30° C. The reaction mixture was stirred between −30° C. to 0° C. for 30 min, and poured into ice. The resulting solid was collected by filtration, washed with water, and dissolved in ethyl acetate. The obtained solution was washed with water and saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (ethyl acetate/hexane) to give the title compound (2.2 g).
Loading…