Recyclization in the Series of Spiro[indole-3,5′-pyrimido[4,5-b]quinoline]-2,2′,4′-triones Prepared by a Three-Component Reaction of Isatins with (Thio)barbituric Acids and Electron-Rich Anilines
5-b]quinoline]-2,2′,4′-trione derivatives prepared by a three-component reaction of (thio)barbituricacids, electron-rich aromaticamines, and isatins was observed. A ring–ring transformation in the series of spiro[indole-3,5′-pyrimido[4,5-b]quinoline]-2,2′,4′-trione derivatives prepared by a three-component reaction of (thio)barbituricacids, electron-rich aromaticamines, and isatins was observed.