Research Into The Synthesis, Structure And Biological Activity Of Pyrazole And 1,2,4-Triazole Compounds

This thesis has been divided into two main sections based on the nature of related contents, totalizing four small portions, and mainly focusing on the investigations into the synthesis, characterization and determination of biological activity of pyrazole and triazole compounds.In the first chapter are reported unexpected and highly regioselective acylation and alkylation reactions of a 1 -unsubstituted pyrazole derivative, correcting the incorrect results in earlier reports by other authors. The acylation reaction was discovered by chance, and in order to investigate the generality of this kind of nucleophilic substitution, the alkylation reaction of this pyrazole derivative was subsequently performed, which justified the above anticipation. The proposed reaction mechanism involves both steric and electronic effects. The second chapter is mainly concerned with a novel and efficient procedure for the synthesis of the imidazo[l,2-b]pyrazole framework, and this two-step procedure involves a variety of 5-amino-1H-pyrazoles and commomly encountered alpha-bromoketones as starting materials. The principle that the stability of the entire molecule is more preferable than the local one was established in the reaction mechanism. A methodology for the synthesis of a number of functionalized pyrazole derivatives bearing chiral side-chains from a naturally occurring and inexpensive chiral source D-glucose was presented in chapter three, which provides theoretical and experimental supports to the investigations into the synthesis of hydrophilic and highly bioactive compounds. Chapter four describes a novel coupling reaction of a variety of aminotriaole compounds. Thus, the coupling reaction of 4-amino-5-mercapto-3-substituted-l,2,4-triazoles generated the symmetrically substituted hydrazines in the presence of a thiohemiacetal from Pummerer rearrangement, alpha-hydroxy-alpha-methylthioacetophenone.All the reported compounds in the thesis are pure and have been subjected to spectroscopic and elemental analyses, including IR, NMR (¹H NMR, ¹³C NMR, and 2D NMR), and MS (ESI technique and FAB technique), and many compounds have been analyzed by single-crystal X-ray diffraction, providing unambiguous proof for their structures. The tests for such biological activities of many compounds as herbicidal, fungicidal and plant-growth regulation, have also been carried out.A number of synthons have been employed during the research, including ethyl dimethylthiomethyleneacetoacetate, dimethylthiomethylenemalononitrile, ethyl dimethyl-...