Synthesis, Structure Characterization And Biological Activity Of Pyrazole Acylamides Containing 1, 3, 4-thiadiazole (& Piperazine)

Today heterocyclic compounds especially heterocyclic with "N" occupy the important position in the research and development of pesticide. Pyrazole compounds is a kind of very important compounds, which have good biological activity and used widely in the field of coordination, agriculture, medicine and coordination chemistry. Because of its structure of "N-C-S", 1,3,4-thiadiazole compounds can be used as biological activity center chelating some metal ions with good permeability and can play a better effect in weeding, plant growth regulating, sterilization, insecticidal, etc. In addition, the applications in pharmacological are aroused great interest. Piperazine derivatives have also attracted more and more attention due to their excellent activities. The synthesis and active research of the compounds containing any heterocyclic have been reported, but it is rare about compounds with pyrazoles ring and 1,3,4-thiadiazole ring, and few about compounds with 3 kinds of aforementioned heterocyclic.4-Substituted acetophenone and diethyl oxalate were used as the starting materials, based on the methods of Claisen condensation, Knorr cyclization, methylation, chlorination, hydrolyzation the ester, 5 pyrazole carboxylic acids were obtained, and then 5 kinds of acyl chloride were synthesized with pyrazole carboxylic acids and thionyl chloride; 6 kinds of 1,3,4-thiadiazole derivatives were received from substituted carboxylic acids and thiosemicarbazide using phosphorus acylchloride as the dehydrating agent. Pyrazole, 1,3,4-thiadiazole were connected together though acylamidation reaction and 30 target compounds which have not yet been reported in the literatures were synthesized. The amino in 2-amino-5-(4-nitrophenyl)-1,3,4-thiadiazole were chlorinated firstly, the obtained compound reacted with piperazine, and then combined with the pyrazole acyl chloride, 5 new target compounds were received containing pyrazole, 1,3,4-thiadiazole and piperazine. A Co2+ coordination compound was got through intermediate products coordinated with transition metal ions.All the target compounds and intermediates were characterized by IR, NMR. A representative compound was characterized in the 2D for further studying the structures of the target compounds. In order to confirm the structures of new coordination compound, its structure was characterized by X-ray single crystal diffraction measurement.Besides, primary biological activity experiments have been done to all the target compounds. It is found from the results that the activities of all the target compounds were not high and 6 of them were antiblastic to wheat gemma in the concentration of 10 ppm, and all of them have some weeding activities in the concentration of 100 ppm.