Catalytic synthesis of dihydropyridines by domino reaction of terminal alkynes, carbodiimides, and acetylenic esters

A novel additive-assisted reaction for the synthesis of dihydropyridines using copper salts as catalyst has been described. The (imino)pyridine skeletons were obtained in acceptable yields through a domino reaction involving terminal alkynes, carbodiimides, and acetylenic esters. Control experiments were conducted to explore the reaction path and to prove the mechanism proposed for the reaction.