The Investigation On The Synthesis Of Linked And Fused Heterocyclic Compounds Bearing 1,2,4-Triazine Nucleus

This thesis has been divided into four main sections based on the nature of related contents, and mainly focusing on the investigations into the synthesis and characterization of 1,2,4-triazine compounds.In order to search for leading compounds possessing new structures, thirty-three novel compounds containing the 1,2,4-triazine framework with different structures were synthesized from (5-aryl-1,2,4-triazin-3-yl)-hydrazine and 3-amino-5-aryl-1,2,4-triazine as building blocks.The structures of all the synthesized compounds were characterized by IR, 1H NMR and elemental analysis, and some of them were further confirmed by MS. In addition, two target compounds were selected for X-ray crystal diffraction to determine their absolute structures.The synthesis of ethyl 5-aryl-3 -substitutedpyrazolo- 1,2,4-triazine (5a-k), which are obtained from (5-aryl-1,2,4-triazin-3-yl)-hydrazine(3a-c) with 2-dimethylamino-methylene-3-oxo-butyric acid ethyl ester, 2-(bis-methylsulfanyl-methylene)malono-nitrile, 2-cyano-3,3-bis-methylsulfanyl-acrylic acid ethyl ester, ethylethoxymethylene-cyanoacetate and ethyloxymethylenemalonitrile respectively, were investigated in this paper.New twelve compounds of 1,2,4-triazolo[4,3-b]1,2,4-triazine(7a-l) were obtained from N-arylidene-N'-(5-aryl-1,2,4-triazin-3-yl)-hydrazine(6a-r) through an intramolecular cyclization in the presence of the non-metal oxidant IBD, and the compounds 6a-r were obtained by the reaction (5-aryl-1,2,4-triazin-3-yl)-hydrazine(3a-c) with sustitutedbenzaldehyde. This methodology has the advantages of mild conditions, high yields and convenient operation. Meanwhile its reaction mechanism was discussed.In this paper, seven novel compounds with structure of imidazo[4,3-b]1,2,4-...