dimethyl 1-(N-phenylamino)-ethene-1,2-dicarboxylate

3-methoxycarbonyl-4-oxo-1H-quinoline-2-carboxylate

dimethyl 4-oxo-1H-quinoline-2,3-dicarboxylate

4,5-dimethoxycarbonyl-1-phenyl-1H-pyrrole-2,3-dione