O=[C:2]1[C:7]([C:8]([O:10][CH3:11])=[O:9])=[CH:6][CH:5]=[CH:4][O:3]1.[CH3:12][C:13]1[CH:19]=[CH:18][CH:17]=[CH:16][C:14]=1[NH2:15].Cl.C(N=C=NCCCN(C)C)C.Cl>O1CCCC1.CN(C)C=O.CN(C)C1C=CN=CC=1>[CH3:12][C:13]1[CH:19]=[CH:18][CH:17]=[CH:16][C:14]=1[N:15]1[CH:4]=[CH:5][CH:6]=[C:7]([C:8]([O:10][CH3:11])=[O:9])[C:2]1=[O:3]To a solution of methyl 2-oxo-2H-pyran-3-carboxylate (3 g, 19.5 mmol) in tetrahydrofuran (30 mL) and N,N-dimethylformamide (10 mL) was added 2-methylaniline (2.09 g, 19.5 mmol), and the mixture was stirred at room temperature for 7 hr. 4-Dimethylaminopyridine (119 mg, 0.974 mmol) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (4.48 g, 23.4 mmol) were added to the reaction mixture, and the mixture was further stirred at room temperature for 17 hr. 1N Hydrochloric acid was added to the reaction solution, and the mixture was extracted 3 times with ethyl acetate. The combined organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate and filtered, and the solvent was evaporated under reduced pressure. The obtained residue was purified by silica gel column chromatography (NH silica gel, ethyl acetate/hexane=1/1) to give the title compound (882 mg, 19%) as yellow crystals.
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