A copper-catalyzed tandem cyclization reaction of <i>N</i>-acyl enamines and electron-deficient alkynes: direct synthesis of alkynyl substituted pyridines

A copper-catalyzed coupling-cyclization reaction of <i>N</i>-acyl enamides with electron-deficient alkynes is developed. This reaction tolerates a wide range of <i>N</i>-acyl enamines and provides a simple and efficient method for the synthesis of 3-alkynyl-substituted pyridines in good to high yields from easily available acyclic starting materials with only water and hydrogen as the by-products in a single step.