Synthesis and Biological Activity of Some Novel Trifluoromethyl-substituted 1,2,4-triazole and Bis(1,2,4-triazole) Mannich Bases Containing Piperazine Rings

A series of trifluoromethyl-substituted 1,2,4-triazole Mannich base 6 and bis(1,2,4-triazole) Mannich base 7 containing pyrimidinylpiperazine rings via the Mannich reaction were synthesized and characterized by infrared (IR), (1)H nuclear magnetic resonance (NMR), and elemental analysis. The fungicidal tests indicated that most of compounds 6 and 7 possessed excellent fungicidal activity. Among 19 novel compounds, some showed superiority over commercial fungicides Dimethomorph, Thiophanate-methyl, Iprodione, and Zhongshengmycin. Some compounds also exhibited favorable herbicidal activity in the preliminary studies. On the basis of the comparative molecular field analysis (CoMFA), five novel compounds were subsequently synthesized, their activities were estimated fairly accurately, and compounds 6-A1 and 7-A2 displayed good fungicidal activity against Pseudoperonospora cubensis (96.9 and 84.9%) as 6h and 7c, respectively.