Synthesis, Structure and Biological Activities of Novel 2-(Trifluoromethyl)-6-arylimidazo[2,1-b][1,3,4]-thiadiazole (bis-)Mannich Base Derivatives Containing Substitutedpiperazine Moiety

A convenient and practicable method for the synthesis of the novel 2-(trifluoromethyl)-6-arylimidazo[2,1-b][1,3,4]-thiadiazole (bis-)Mannich base derivatives containing various substitutedpiperazine motif has been developed based on the fused-heterocycle intermediate. The new structures were identified through melting points, H-1 NMR, C-13 NMR, F-19 NMR, elemental analysis (or HRMS) and X-ray single-crystal diffraction. The pesticidal bioassays showed that some of compounds exhibited good fungicidal activities against Cercospora arachidicola, Physalospora piricola and Rhizoctonia cereali at 50mg/L; some of them displayed favourable insecticidal activities against oriental armyworm (Mythimna separata Walker) at 200mg/L, particularly, Vk and Vm with mortality rate of 75% and 80% respectively, could be considered as new insecticidal lead compounds for further structural optimization.