[C:1]([NH:4][CH:5]([C:10](=O)[CH2:11][CH2:12][CH2:13][CH2:14][O:15][CH3:16])[C:6]([O:8][CH3:9])=[O:7])(=O)[CH3:2].[NH2:18][C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1.FC(F)(F)C(O)=O>C(#N)CCC>[CH3:16][O:15][CH2:14][CH2:13][CH2:12][CH2:11][C:10]1[N:18]([C:19]2[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=2)[C:1]([CH3:2])=[N:4][C:5]=1[C:6]([O:8][CH3:9])=[O:7]Methyl 2-(acetylamino)-7-methoxy-3-oxoheptanoate (5.45 g), aniline (3.01 ml) and trifluoroacetic acid (2.48 ml) were dissolved in butyronitrile (30 ml), and the reaction mixture was heated under reflux for 2 hr. The reaction mixture was cooled to room temperature and concentrated under reduced pressure. 3.6M Aqueous potassium carbonate solution was added to the obtained residue and the mixture was extracted with ethyl acetate. The extract was washed with saturated brine, and dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure. The residue was subjected to silica gel column chromatography, and a fraction eluted with ethyl acetate-hexane (10:90-100:0) was concentrated under reduced pressure to give the object product (3.88 g).
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