Study of the iodine-promoted cyclization of 4,5-diethynyl-1,2,3-triazoles for the synthesis of triazole-iodoheterocyclic dyads

A series of functionalized 4,5-bis(arylethynyl)triazoles were prepared by a copper-catalyzed cycloaddition of 1-iodobuta-1,3-diynes and azides and subsequent Sonogashira reaction of iodoethynyltriazoles with substituted arylacetylenes. The iodine-promoted cyclization of 4,5-bis(arylethynyl)triazoles involved only one triple bond and led to the formation of 2-triazolyl-3-iodoheteroindenes or 5-(4-iodoisochromeno)triazoles.