Synthese von Pyridonen aus Enaminen und Cyanessigsäuren

摘要: Reaction of enamines1 a–e with cyanoacetic acids2 a,b in acetic anhydride at about 100°C yields the α-cyanoacetylated enamines3 a–g. Under same conditions methyl 4-cyano-2-(2-pyridyl)-acetoacetate3 h is obtained from 2-pyridylacetate and2 a. Compounds3 are cyclized hydrochloric acid yielding 4-hydroxy-2-pyridones4; on other hand ethanolic sodium ethoxide solution 2-amino-4-pyridones obtained. The esters5 andd saponified to give acids7 a–c which decarboxylate 250°C to8 a–c.