Study On A New Synthetic Strategy Of 3,5-Disubstituted-1-Phenyl- 1,2,4 -Triazole Derivatives

Studying the synthesis of heterocyclic compounds and the biologic activity is one of the most spirited items in organic chemistry .1,2,4-Triazole derivatives are fascinating in multitudinous heterocyclic by virtue of their activity and excellent potential.This thesis was on basis of former research work. And at the same time we provided a new and convenient strategy for the synthesis of 1,2,4-triazole derivatives. The first step was to synthesize α-nitro hydrazone precursors which is used as the next material by utilizing Michael addition reaction. The second step was to use these accepted α-nitro hydrazones to synthesize triazole derivatives in the mild condition and through forming amidrazones, cyclization, oxidization, etc. So, the subject of this thesis is the new strategy for the synthesis of 1,2,4-triazole derivatives.In part one is classified under different strategies. The numerous preparations of 1,2,4-triazole derivatives recently reported in the literature. They are (1) the use of hydrazine derivatives (2) cyclization of nitrilimine (3) the use of other heterocyclic systems (4) the use of parent 1,2,4-triazole etc.In part two are reported the new and convenient synthetic strategy of 1,2,4-triazole derivatives. The very important step is the diazotization and subsequent addition with appropriate nitro derivatives. And the key step is the transformation of nitrohydrzones and amidrazones into 1,2,4-triazole derivatives through the initial formation of azoimines and their tautomerization, cyclization and oxidization, etc.In the first step the nitro compounds were obtained from nitromethane and acrylic ester etc. by undergoing Michael addition reaction. In the second step these accepted nitro compounds were readily converted into ions in alcohol at 0～5℃ for 1～1.5h and then proceeded transforming into α-nitrohydrzones in high yields. In the third step α-nitrohydrzones and primary amines was refluxed in the same amine for 3h; evaporation of excess amine followed by addition of toluene, sodium nitrite and TEBAC give 1,2,4-triazole derivatives after reflux in good yields.All the products containing five-membered ring and the others were identified on the basis of their analytical data, such as IR,H-NMR and MS.The results indicate that the strategy we used to synthesize 1,2,4-triazole derivatives has significant advantage: common available materials, mild reaction conditions, safety operations and high yields. It can be expected that throughα-nitrohydrzone precursors the synthesis of 1,2,4-triazole derivatives which display a wide range of potent biological activities and excellent potential will come true.