Substituent-dictated concise synthesis of 4,6-disubstituted N-alkyl-2-pyridones and 2-aminopyridines

Functionalized N-alkyl-2-pyridones and 2-aminopyridines are useful precursors for the synthesis of various heterocyclic compounds of therapeutic importance. In this paper we have delineated and illustrated a direct methodology for the synthesis of 6-aryl-N-hydroxyethyl-4-methylsulfanyl-2-pyridones through the ring transformation of 6-aryl-3-cyano-4-methylsulfanyl-2H-pyran-2-ones by ethanolamine. Surprisingly, the analogous reaction with 6-aryl-3-cyano-4-piperidin-1-yl-2H-pyran-2-ones afforded 2-aminopyridines in high yield instead of the corresponding 2-pyridones.