Nitration of Bio-related Compounds with Peroxynitrite Mechanistic Implications to Biological Nitration

为了深入了解生物硝化的机理，研究了过氧亚硝酸盐与一些生物相关模型化合物在缓冲水溶液和乙腈中的反应。所使用的化合物包括酚类、N， N- i二甲基苯胺和活性烯烃，如二苯乙烯、1,4 -二苯基丁二烯和1,4 -二苯基丁烯。在碱性水溶液中，臭氧氧化叠氮化钠生成过氧亚硝酸盐。苯酚在芳香环上同时发生硝化和羟基化反应，产物分布呈典型的亲电性。副产物包括醌和环己二烯。A^A^-二甲基苯胺经历了广泛的去甲基化，这表明亚硝基离子作为活性物质参与其中。二苯乙烯有苯乙烯、环氧二苯乙烯和苯甲醛，以及一些环硝化产物。氧化裂解碳碳键的机理目前还不清楚，因为氧化二苯乙烯、1,2 -二苯乙二醇和二苯基羟基氧基乙烷酮对过氧亚硝酸盐都是惰性的。在相同的条件下，二苯基乙酰与环硝化产物同时产生苯并为主要产物；奇怪的是，它的替换模式只有ortho和meta。烯烃键的反应性比乙炔键强，但差异并不像亲电过程所期望的那么大。烯烃键和多烯键的相对反应性差异也不大。

In order to get insight into the mechanism of biological nitration, the reaction of peroxynitrite with some bio-related model compounds has been investigated in buffered aqueous solutions and acetonitrile. The compounds employed included phenols, N, N- i dimethylanline and activated olefines such as stilbene, 1, 4-diphenylbutadiene and 1, 4- diphenylbutenyne. Peroxynitrite was generated by the oxidation of sodium azide with ozone in aqueous alkaline solution.With phenols, concurrent nitration and hydroxylation took place on aromatic ring and the product distribution pattern showed a typical electrophilic nature. Side products included quinones and cyclohexadienes. A^A^-Dimethylaniline underwent extensive demethylation, which suggested involvement of the nitrosonium ion as active species. Stilbene afforded benzil, stilbene epoxide and benzaldehyde, together with some ring nitration products. The mechanism of oxidative cleavage of the carbon-carbon bond is not clear at present, since stilbene oxide, 1, 2-diphenylethanediol and diphenylhy＆roxyethanone were all found to be inert toward peroxynitrite. Under similar conditions, diphenylacetyle afforded benzil as the main product along with ring nitration products ; strangely enough, the substitution pattern of which was only ortho and meta. The olefinic bond was more reactive than the acetylenic one, but the difference was not so large as expected from the electrophilic process. The difference in relative reactivity between the olefinic and polyenic bonds was not so large, either.