Synthesis and Biological Activity of Novel Furan/Thiophene and Piperazine‐Containing (Bis)1,2,4‐triazole Mannich Bases

Series of novel furan/thiophene and piperazine‐containing 1,2,4‐triazole Mannich bases and bis(1,2,4‐triazole) Mannich bases have been conveniently synthesizedviaMannich reaction with triazole Schiff bases, various piperazine derivatives, and formaldehyde as intermediates in good yields. Their structures were characterized by melting points,1H NMR,13C NMR, IR and elemental analysis. The preliminary bioassay showed that most compounds exhibited significantin vitroandin vivofungicidal activity against several test plant fungi. Among 32 new compounds, the trifluoromethyl‐containing compounds showed superior activity than the methyl‐containing ones. Several compounds, such asF8,F9,F10,G5,H7,H8,I3andI4, were comparable with some commercial fungicides against different fungi during the present study and could be further structurally optimized. Meanwhile, several compounds showed good herbicidal activity againstBrassica campestrisat 100 µg/mL and KARI inhibitory activity at 200 µg/mL. However, compounds exhibited poor insecticidal activity against oriental armyworm at 200 µg/mL in the preliminary studies. The research results will provide useful information for the design and discovery of new agrochemicals with novel heterocyclic structures.