Metal-Free Synthesis of Fully Substituted Pyridines via Ring Construction Based on the Domino Reactions of Enaminones and Aldehydes

An unprecedented domino reaction involving primary enaminones/enaminoesters and aldehydes has been developed for the synthesis of fully substituted pyridines. The construction of the products has been accomplished via the cascade generation of two C-C and one C-N bond by simply using TfOH as a promoter.