Regioselective synthesis of two types of highly substituted 2-pyridones through similar multicomponent reactions

The refluxing of a mixture of ethylcyanoacetate, aromatic aldehydes, and primary monoamines in ethanol produces highly substituted 2-amino-6-pyridones such as 2-amino-1-(alkyl)-5-cyano-6-oxo-4-(aryl)-1,6-dihydropyridine-3-ethylcarboxylates in one-pot. On the other hand the refluxing of a mixture of ethylcyanoacetate, aromatic aldehydes, and primary diamines (1,2-ethylenediamine/1,3-propylenediamine) in ethanol furnishes symmetrical zwitterionic 2-pyridones such as 1-(2-amino-ethyl/3-amino-propyl)-6-hydroxy-2-oxo-4-(aryl)-1,2-dihydropyridine-3,5-dicarbonitriles. The result shows that primary diamines and monoamines react differently in the reactions, which provides new mechanistic insight into the regioselective synthesis of these biologically important compounds.