[C:1]([C:4]1[CH:5]=[CH:6][C:7]2[O:12][CH:11]=[C:10]([C:13]#N)[C:9](=[O:15])[C:8]=2[CH:16]=1)(=[O:3])[CH3:2].[C:17]([CH2:19][C:20]([O:22][CH2:23][CH3:24])=[O:21])#[N:18].[NH:25]1CCCCC1>C(O)C>[C:1]([C:4]1[CH:5]=[CH:6][C:7]2[O:12][C:11]3=[N:18][C:17]([NH2:25])=[C:19]([C:20]([O:22][CH2:23][CH3:24])=[O:21])[CH:13]=[C:10]3[C:9](=[O:15])[C:8]=2[CH:16]=1)(=[O:3])[CH3:2]In ethanol (800 ml) was suspended 6-acetyl-4-oxo-4H-1-benzopyran-3-carbonitrile (32 g). To the suspension were added ethyl cyanoacetate (23.9 ml) and piperidine (23.7 ml). The mixture was refluxed for one hour, then cooled to room temperature. The resulting crystals were collected by filtration, washed with ethanol, then with acetone, followed by drying to give ethyl 7-acetyl-2-amino-5-oxo-5H-[1]benzopyrano[2,3-b]pyridine-3-carboxylate as yellow crystals (46.3 g). Melting point: >300° C.
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