The Synthesis and Reactions of Polyazaaromatics

从去年开始，我们一直在研究1,2,3,4-四嗪及其苯并衍生物的合成方法。为了评估我们的反应系统的范围和局限性。n -氨基吡唑被各种氧化剂氧化得到n -亚硝基衍生物，并被重排成相应的1,2,3-三嗪。由于该反应体系对多种1,2,3-三嗪衍生物有效，我们将该反应应用于n -氨基- 1,2,3-三唑的氧化。因此，1-氨基-三氮唑-三氮唑氧化得到三氮唑- 1,2,3,4 -四氮，这是第一个芳香四氮衍生物。这个反应被认为是有实际用途的，因为有许多三唑衍生物很容易得到。然而，其他四嗪衍生物不能通过该方法得到。利用分子轨道计算研究了这一失败的原因，结果表明1,2,3,4-四氮会通过逐步自由基过程而不是协同自由基过程分解，因此合成后的化合物是稳定的。因此我们决定研究另一种氧化剂与n -氨基化合物反应，并发现一氧化氮作为一种生物自由基备受关注，可以作为多种生理信号的传递者。以不同的方式与氨基化合物反应，这取决于分子氧与NO的数量。

Since last year, we have been investigating the synthetic method for 1,2,3,4-tetrazines and their benzo derivatives. In order to evaluate the scope and limitation of our reaction system. N-aminopyrazoles were oxidized byy various oxidizing agents to give N-nitrene derivatives, which were rearranged to corresponding 1,2,3-triazines. Since this reaction system was revealed to be effective for diverse 1,2,3-triazine derivatives, we applied the reaction to the oxidation of N-amino-l, 2,3-triazole. Thus, the oxidation of 1-amino-triazolotriazole afforded the triazolo-l, 2,3,4-tetrazine, which is the first aromatic tetrazine derivative. The reaction was thought to be of practical use because there are many triazole derivatives which are readily available. The other tetrazine derivatives were, however, not obtained by this procedure. The cause of this failure was studied using the molecular orbital calculations, and the results showed that 1,2,3,4-tetrazine would be decomposed via stepwise radical processes rather than concerted ones, thus the compound would be stable if it was synthesized Thus we decided to study another oxidizing agents to react with N-amino compounds, and found that nitric oxide, which has attracted much attention as a biological radical to act as diverse physiological signal transmitters, reacted with amino compounds in various manners depending upon the amount of molecular oxygen vs. NO.