A　Cu-catalyzed　interrupted　click　reaction　for　the　synthesis　of　3-perfluoroalkyl-substituted　1,2,4-triazinones　is　developed.　The　reaction　between　the　terminal　alkynes　with　azides　and　pentafluoropropionic　or　heptafluorobutyric　anhydride　proceeds　smoothly　to　afford　the　corresponding　pentafluoroethylated　or　heptafluoropropyled　products　in　good　yields.　This　protocol　is　applicable　to　various　types　of　substrates　including　arylacetylenes　and　aliphatic　azides　having　electron-rich　and　electron　deficient　groups.　The　broad　substrate　scope　and　functional　group　tolerance　of　the　reaction　makes　this　approach　a　practical　method　for　the　synthesis　of　valuable　3-perfluoroalkyl-substituted　1,2,4-triazinones.　Some　of　the　title　compounds　showed　fungicidal　activity　against　cucumber　downy　mildew　(CDM).　(C)　2019　Elsevier　Ltd.　All　rights　reserved.