Synthesis and reactions of 3-(N-arylcarbamoyl)-2-methylcinchoninic acid
The Pfitzinger reaction between acetoacetic acid arylamides and the potassium salt of isatinic acid leads in good yield to 3-(N-arylcarbamoyl)-2-methylcinchoninic acids. Refluxing the latter in 2-propanol produced N-substituted imides of 2-methylquinoline-3,4-dicarboxylic acids and, with benzaldehyde in p-xylene in the presence of piperidine, to N-phenylimides of 2-styrylquinoline-3,4-dicarboxylic acids.