From Generation of Peroxo and High-Valent Diiron Complexes to Enantioselective C-H Oxidation Catalysts

从过氧和高价二铁络合物的生成到对映选择性 C-H 氧化催化剂

• 批准号: 495337180
• 负责人: Professor Dr. Thorsten Glaser
• 金额: --
• 依托单位: Arbeitsgruppe Anorganische Chemie I
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/495337180?language=en
• 关键词: Generation; Peroxo; Valent; Diiron; Complexes

Enzymes with a non-heme diiron active site (NHFe2) activate dioxygen in biological systems to catalyze a variety of oxidation and/or oxygenation reactions of organic substrates, that are also interesting and promising for synthetic applications. One such reactivity is the selective C-H hydroxylation of not activated organic molecules including the least reactive substrate CH4 used by methane monooxygenase (sMMO). The catalytic cycles of NHFe2 generally employ a diferrous form that reacts with dioxygen to a peroxo-diferric intermediate. The active species is supposed to be either this peroxo-diferric species or a species derived from it. In sMMO, the peroxo intermediate, P, converts to a high-valent Fe(IV)Fe(IV) active species, Q. Despite strong worldwide efforts to obtain functional bioinspired diiron models for this reactivity, the actual catalytic performances are not good enough for application. Most ligand systems used so far are mainly comprised of nitrogen-containing donors. However, in sMMO there is a carboxylate-rich coordination environment, that is also characteristic for many other diiron enzymes. This implies, that the reactivity of these otherwise structurally very similar diiron active sites depends strongly on the terminal donors. In this respect, we want to establish a family of diiron complexes with dinucleating ligands that vary in their terminal donors including pyridine, imidazole, phenolate, and carboxylate and all kind of mixed forms to study their reactivity for building peroxo and/or high-valent diiron species. Besides the elucidation of the molecular and electronic structures of these peroxo and/or high-valent species, we will investigate their reactivities in the hydroxylation of selected substrates. As it is thought that the molecular and electronic structure dictate reactivity, we intend to obtain correlations between the molecular and electronic structures with their reactivities so that we can identify the best catalytic systems for selective C-H oxidations. For this, we will synthesize new derivatives of our family of dinucleating ligands with different terminal donors, we will synthesize their diiron complexes, we will try to obtain high-valent and peroxo species, and we will study their reactivites and catalytic abilities. However, we don’t want to stay with traditional substrates for C-H activation as cyclohexane, but we also want to introduce an enantioselectivity to this C-H bond activation. Therefore, we will try to introduce chirality into the dinucleating ligand system so that we can obtain chiral catalysts for the enantioselective C-H activation of carefully chosen substrates.

具有非血红素二铁活性位点（NHFe 2）的酶在生物系统中激活分子氧以催化有机底物的各种氧化和/或加氧反应，这对于合成应用也是有趣的和有前途的。一种这样的反应性是未活化的有机分子的选择性C-H羟基化，包括甲烷单加氧酶（sMMO）使用的反应性最低的底物CH 4。NHFe 2的催化循环通常采用与分子氧反应成过氧二铁中间体的二亚铁形式。在sMMO中，过氧中间体P转化为高价Fe（IV）Fe（IV）活性物种Q。尽管全世界都在努力获得这种反应性的功能性生物启发二铁模型，但实际的催化性能还不够好。迄今为止使用的大多数配体系统主要由含氮供体组成。然而，在sMMO中存在富含羧酸盐的配位环境，这也是许多其他二铁酶的特征。这意味着，这些结构上非常相似的二铁活性位点的反应性强烈依赖于末端供体。在这方面，我们希望建立一个家庭的双核配体，在其末端供体，包括吡啶，咪唑，酚盐，羧酸盐和所有种类的混合形式的二铁配合物，以研究其反应性建设过氧和/或高价二铁物种。除了这些过氧和/或高价物种的分子和电子结构的阐明，我们将研究它们在选定的底物的羟基化的反应性。由于人们认为，分子和电子结构决定的反应性，我们打算获得的分子和电子结构与它们的反应性之间的相关性，使我们能够确定最好的催化体系选择性C-H氧化。为此，我们将合成具有不同末端供体的双核配体家族的新衍生物，我们将合成它们的二铁配合物，我们将尝试获得高价和过氧物种，并且我们将研究它们的反应活性和催化能力。然而，我们不想停留在传统的C-H键活化底物环己烷，但我们也想引入对映选择性，这种C-H键活化。因此，我们将尝试在双核配体体系中引入手性，以获得对映选择性C-H活化的手性催化剂。