Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Dalton Trans. 2012 Aug 28;41(36):10883-99. doi: 10.1039/c2dt30806a.
The S-oxygenation of cysteine with dioxygen to give cysteine sulfinic acid occurs at the non-heme iron active site of cysteine dioxygenase. Similar S-oxygenation events occur in other non-heme iron enzymes, including nitrile hydratase and isopenicillin N synthase, and these enzymes have inspired the development of a class of [N(x)S(y)]-Fe model complexes. Certain members of this class have provided some intriguing examples of S-oxygenation, and this article summarizes these results, focusing on the non-heme iron(II/III)-thiolate model complexes that are known to react with O(2) or other O-atom transfer oxidants to yield sulfur oxygenates. Key aspects of the synthesis, structure, and reactivity of these systems are presented, along with any mechanistic information available on the oxygenation reactions. A number of iron(III)-thiolate complexes react with O(2) to give S-oxygenates, and the degree to which the thiolate sulfur donors are oxidized varies among the different complexes, depending upon the nature of the ligand, metal geometry, and spin state. The first examples of iron(II)-thiolate complexes that react with O(2) to give selective S-oxygenation are just emerging. Mechanistic information on these transformations is limited, with isotope labeling studies providing much of the current mechanistic data. The many questions that remain unanswered for both models and enzymes provide strong motivation for future work in this area.
半胱氨酸与氧气的 S-氧合反应生成半胱氨酸亚磺酸发生在半胱氨酸双加氧酶的非血红素铁活性部位。类似的 S-氧合事件也发生在其他非血红素铁酶中，包括腈水合酶和青霉素 N 合酶，这些酶激发了一类 [N(x)S(y)]-Fe 模型配合物的发展。该类中的某些成员提供了一些有趣的 S-氧合的例子，本文总结了这些结果，重点介绍了已知与 O(2)或其他 O-原子转移氧化剂反应生成硫氧代物的非血红素铁(II/III)-硫醇ate 模型配合物。这些体系的合成、结构和反应性的关键方面，以及氧合反应的可用的任何机理信息都有所呈现。许多铁(III)-硫醇ate 配合物与 O(2)反应生成 S-氧代物，硫醇供体的氧化程度因不同的配合物而异，取决于配体、金属几何形状和自旋态的性质。首次出现的与 O(2)反应生成选择性 S-氧合的铁(II)-硫醇ate 配合物的例子刚刚出现。这些转化的机理信息有限，同位素标记研究提供了当前大部分的机理数据。对于模型和酶，仍然存在许多未解决的问题，为该领域的未来工作提供了强烈的动力。
