Amidate ion-mediated intramolecular ring transformation of 2-pyrones to 2-pyridones

Herein, we report a new and cost-effective methodology for synthesizing N-substituted 2-pyridone-3-carboxylic acids (2) from 2-pyrone-3-carboxamides (1) with a good yield at room temperature. The notable feature of this reaction is the promotion of amidate ion formation mediated by NaH to initiate intramolecular ring transformation. In addition to ring transformation, simultaneous decarboxylation and substitution under the metal-free condition in one pot have been achieved to yield N-substituted 2-pyridones (3) from 1.