Synthesis of 3-perfluoroalkyl-substituted 1,2,4-triazinones through copper(I)-catalyzed interrupted click reaction

Abstract

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).