C1(OC2C=CC=CC=2)C=CC=CC=1.[N:14]1[CH:19]=[CH:18][CH:17]=[C:16]([NH:20][CH:21]=[C:22]([C:28]([O:30]CC)=O)[C:23]([O:25][CH2:26][CH3:27])=[O:24])[CH:15]=1>C(O)C>[OH:30][C:28]1[C:15]2[C:16](=[CH:17][CH:18]=[CH:19][N:14]=2)[N:20]=[CH:21][C:22]=1[C:23]([O:25][CH2:26][CH3:27])=[O:24]A mixture of 265 g. of diphenyl and 735 g. of diphenyl ether is heated to 255° C., and then the above diethyl 2-([3-pyridylamino]methylene)-malonate is added all at once. The temperature of the mixture is maintained at 255° C. until ethanol is no longer evolved. The mixture is cooled to 25° C. and the precipitate is removed by filtration. It is washed liberally with hexane and dried. This affords 40.5 g. (75% yield) of ethyl 4-hydroxy-1,5-naphthyridine-3-carboxylate.
読み込み中…