Palladium-catalyzed cycloisomerisation reaction of 1,6-enyne acetic esters to form five-embered nitrogenated heterocyclic conjugated trienes

A palladium-catalyzed cycloisomerisation reaction of 1,6-enyne acetic esters have been developed. This cyclization reaction shows excellent regioselectivity and good functional group tolerance to obtain five-membered nitrogenated heterocyclic conjugated trienes in moderate to excellent yields. The resulting conjugated trienes could be facilely converted to highly substituted benzenes through Diels-Alder reactions. (C) 2017 Elsevier Ltd. All rights reserved.