[N+:1]([C:4]1[CH:5]=[C:6]([CH:8]=[CH:9][CH:10]=1)[NH2:7])([O-:3])=[O:2].[CH2:11](N(CC)CC)C.O1[CH2:22][CH2:21][CH2:20]C1.[C:23](=[O:26])([O-])[O-:24].[K+].[K+]>C(#N)C.CN(C)C1C=CN=CC=1.CO.O>[C:21]([O:24][C:23](=[O:26])[NH:7][C:6]1[CH:8]=[CH:9][CH:10]=[C:4]([N+:1]([O-:3])=[O:2])[CH:5]=1)([CH3:20])([CH3:22])[CH3:11]
To a solution of 3-nitroaniline (15.4 g, 112 mmol) in acetonitrile (220 ml) were added di-tert-butyl bicarbonate (62.2 g, 285 mmol), triethylamine (23.2 mL, 168 mmol) and N,N-dimethylpyridine-4-amine (1.36 g, 11.2 mmol), and the mixture was stirred at room temperature for 42 hr. The reaction mixture was concentrated under reduced pressure. To a solution of the obtained residue in methanol (100 mL)/tetrahydrofuran (100 mL) was added potassium carbonate (30.8 g, 223 mmol), and the mixture was stirred at 60° C. for 1 hr. To the reaction mixture was added water (200 mL), and the mixture was extracted with ethyl acetate (300 mL, 100 mL). The combined organic layer was washed with saturated brine (50 mL), and dried over anhydrous magnesium sulfate. The insoluble material was filtered off, and the filtrate was concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (hexane/ethyl acetate=100/0→90/10), and the fractions containing the object product were concentrated under reduced pressure. The obtained residue was recrystallized from ethyl acetate and hexane to give the title compound (18.6 g, 70%) as pale-yellow needle crystals.
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