State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, P. R. China.
Chem Asian J. 2012 Oct;7(10):2253-7. doi: 10.1002/asia.201200422. Epub 2012 Jul 3.
A mild process for the selective oxidation of sulfides is in great demand. Therefore, probing the mechanism underlying the biological oxidation of sulfides under ambient conditions may provide valuable insights for the development of such a reaction. Based on porphyrin models of P450 enzymes, evidence of two key intermediates, Int0 and Int1, in this reaction is provided. Spectroscopic studies indicated the formation of a hydroperoxide-iron(III) species (Int0) upon addition of H(2)O(2). This intermediate proved to be highly selective for sulfoxide production. By contrast, a defined porphyrin oxoiron(IV) cation radical (Int1) directly reacted with sulfoxides, leading selectively to the corresponding sulfones. Interestingly, the available sulfoxides reversibly act as a new axial ligand for Int0 forming a more active species Int0(SO). The amount of Int0 increased in the presence of alkyl, aryl, or aromatic sulfides, while Int1 formed in the absence of these sulfides. Thus, sulfoxides and sulfones would selectively form under conditions that favor the corresponding intermediates, which elucidate the biological oxidation pathway.
人们迫切需要一种温和的方法来选择性地氧化硫化物。因此，探究在环境条件下生物氧化硫化物的机制可能为开发这种反应提供有价值的见解。本研究基于细胞色素 P450 酶的卟啉模型，提供了该反应中两个关键中间体 Int0 和 Int1 的证据。光谱研究表明，在添加 H2O2 后形成了过氧化物-铁（III）物种（Int0）。该中间体被证明对亚砜的生成具有高度选择性。相比之下，确定的卟啉氧合铁（IV）正离子自由基（Int1）直接与亚砜反应，选择性地生成相应的砜。有趣的是，可用的亚砜可逆地充当 Int0 的新轴向配体，形成更活跃的物种 Int0(SO)。在存在烷基、芳基或芳族硫化物的情况下，Int0 的量增加，而在不存在这些硫化物的情况下形成 Int1。因此，在有利于形成相应中间体的条件下，亚砜和砜会选择性地形成，这阐明了生物氧化途径。
