A novel platform for modeling oxidative catalysis in non-heme iron oxygenases with unprecedented efficiency
A novel platform for modeling oxidative catalysis in non-heme iron oxygenases with unprecedented efficiency
复制标题
DOI：
10.1002/chem.200800724
复制
发表时间：
2008-01-01
影响因子：
4.3
通讯作者：
Costas, Miquel
中科院分区：
文献类型：
--
作者：
Company, Anna;Gomez, Laura;Costas, Miquel
非血红素单铁依赖性加氧酶是一种非常多样化和通用的酶，参与了许多氧化转化，这也具有潜在的技术意义。[1]这些生物催化剂构成了开发环境友好氧化技术的灵感来源。[2]另一方面，仿生合成催化剂构成了一个有价值的工具，探索非血红素酶执行其化学反应机制。[3]衍生自三脚架TPA（TPA=三（2-甲基吡啶基）-胺）和线性BMPEN（BPMEN= N，N '-双（2-甲基吡啶基）-N，N'-二甲基二氨基乙烷）类型配体的铁络合物是特别特殊的化合物，因为它们能够以显著的效率进行立体选择性酶样转化，例如烷烃羟基化和烯烃环氧化和顺式-二羟基化。[3]这种四齿骨架围绕铁（II）中心，产生具有两个顺式可用配位位点的络合物，所述配位位点可被不稳定配体如CH 3CN或CF 3SO 3占据。与这两个系列的配合物的发展平行，已经探索了包括三-，[4]四-[5]和五齿[6]配体的其他几个例子，但在选择性，通用性和效率方面，它们都不能与TPA和BPMEN系列相比。在这项工作中，我们报告了一个新的家庭的非血红素铁配合物的基础上甲基吡啶衍生的三氮杂环壬烷（TACN）的骨干。这个新的家庭的配合物显示出前所未有的效率，在烷烃和烯烃的立体有择氧化与H2 O2，绕过国家的最先进的氧化TPA和BPMEN配合物催化。[3]我们表明，取代的氮原子上的三氮杂大环和吡啶环的类型是关键的工具，以控制相应的Fe II配合物在催化烷烃和烯烃的氧化反应的选择性。生物激发氧化反应中催化选择性的结构控制使该系列复合物成为模拟铁依赖性加氧酶样反应性的独特且通用的平台。四齿配位体R，R ′ PyTACN（方案1）与FeACHTUNGTRENNUNG（CF 3SO 3）2 ACHTUNGTRENNUNG（CH 3CN）2在THF中反应，得到标题化合物[FeACHTUNGTRENNUNG（CF 3SO 3）2（R，R ′ PyTACN）] 1·CF 3SO 3 -4·CF 3SO 3，为白色至黄色分析纯粉末，其可以在CH 2Cl 2/Et 2 O中重结晶后以结晶形式获得。
Non-heme monoiron dependent oxygenases are emerging as a very diverse and versatile group of enzymes involved in a number of oxidative transformations, which also hold potential technological implications.[1] These biological catalysts constitute a source of inspiration for the development of environmentally benign oxidation technologies.[2] On the other hand, bioinspired synthetic catalysts constitute a valuable tool to explore the reaction mechanisms by which nonheme enzymes perform their chemistry.[3] Iron complexes derived from tripodal TPA (TPA= tris (2-methylpyridyl)-amine) and linear BMPEN (BPMEN= N, N’-bis (2-methylpyridyl)-N, N’dimethyldiaminoethane) type of ligands are particularly exceptional compounds because of their ability to perform stereoselective enzyme-like transformations such as alkane hydroxylation and alkene epoxidation and cis-dihydroxylation, with remarkable efficiency.[3] Such tetradentate backbones wrap around an iron (II) center giving rise to complexes with two cis available coordination sites which can be occupied by labile ligands like CH3CN or CF3SO3. Parallel to the development of these two families of complexes, several other examples including tri-,[4] tetra-[5] and pentadentate [6] ligands have been explored, yet none of them can compare with TPA and BPMEN families in terms of selectivity, versatility and efficiency. In this work we report a novel family of non-heme iron complexes based on the methylpyridine derivatized triazacyclononane (TACN) backbone. This novel family of complexes shows unprecedented efficiency in the stereospecific oxidation of alkanes and alkenes with H2O2, bypassing stateof-the-art oxidations catalyzed by TPA and BPMEN complexes.[3] We show that the type of substitution on the N atoms of the triazamacrocycle and on the pyridine ring are key tools to control the selectivity of the corresponding FeII complexes in catalytic alkane and alkene oxidation reactions. This structural control of the catalytic selectivity in bioinspired oxidation reactions makes this family of complexes a unique and versatile platform to mimic iron dependent oxygenase-like reactivity. Reaction of tetradentate ligands R, R’PyTACN (Scheme 1) with FeACHTUNGTRENNUNG (CF3SO3) 2ACHTUNGTRENNUNG (CH3CN) 2 in THF afforded title compounds [FeACHTUNGTRENNUNG (CF3SO3) 2 (R, R’PyTACN)] 1· CF3SO3–4· CF3SO3, as white to yellow analytically pure powders that could be obtained in crystalline form after recrystallization from CH2Cl2/Et2O.