Manganese complex catalysts for hydrogenation and dehydrogenation reactions

可持续地利用地球上的资源是人类面临的一项核心挑战。贵金属稀有、昂贵，在关键技术中有多种用途。催化就是这样一项关键技术。锰是地壳中含量第三丰富的过渡金属，在加氢和脱氢反应中有望成为贵金属催化剂的“替代品”。如果可以获得新的反应性或选择性，这种“替代”就会变得特别有趣。在最近发表于Angewandte Chemie的三篇（2016年和2017年）初步工作手稿中，我们介绍了用于重要加氢和脱氢反应的新型高活性锰催化剂。我们在提案中着重于三个目标。1. 更好地理解pnp -配体稳定的锰配合物如何在加氢或脱氢反应中起作用，并由此衍生出新的催化应用。2. 基于（手性）pnn -钳形配体的新型锰催化剂的研制。3. 新型锰催化反应的发展，其中氨基醇转化为重要的化合物类别。1. 加氢和脱氢催化的机理研究：在初步工作中，我们可以证明锰催化剂在C=O键加氢中是贵金属催化剂的一个有趣的替代品。化学，2016，论文1)。现在我们还不知道催化循环是如何进行的以及底物的活化是如何发生的。因此，我们提出机理研究，这也允许更合理的催化剂设计。所获得的见解应用于在氢化敏感官能团存在下的亚胺的氢化。除氢化作用外，我们还对脱氢的机理，特别是碱的作用感兴趣。新型（手性）催化剂：锰基加氢和脱氢催化的进展与新型催化剂的开发密切相关。因此，我们计划开发一种新型（也是手性）催化剂。因此，采用了一种简单而可变的配体合成方法。这种新型催化剂在多种反应中得到比较应用。例如，在对映选择性催化方面，亚胺的氢化反应令人感兴趣。3. 新的醇类再官能化反应：在我们的初步工作中，我们可以在脱氢缩合反应中证明Mn-Ir的类比，以合成芳香n-杂环化合物（2 × Angew）。化学，2017，论文2和3)。因此，开发以锰为催化剂合成杂环化合物的新方法是有可能的。除了碱基可调的亚胺合成外，还提出了一种新的嘧啶和咪唑合成方法。初步的工作支持这些方案的可行性。

The sustainable handling of the resources on our planet is a central challenge of humankind. Noble metals are rare, expensive and are used diversely in key technologies. Catalysis is such a key technology. Manganese is the third most abundant transition metal in the earth’s crust and a promising “replacement” for noble metal catalysts in hydrogenation and dehydrogenation reactions. Such a “replacement” becomes especially interesting if new reactivity or selectivity are accessible. In three recent (2016 and 17) preliminary work manuscripts published in Angewandte Chemie, we introduced novel highly active manganese catalysts for important hydrogenation and dehydrogenation reactions. We focus on three aims in the proposal. 1. A better understanding of how PNP-ligand stabilized manganese complexes act in hydrogenation or dehydrogenation reactions and thereof derived novel catalytic applications. 2. The development of novel manganese catalysts based on (chiral) PNN-pincer ligands. 3. The development of novel Mn-catalyzed reactions in which amino alcohols are converted into important classes of compounds. 1. Mechanistic studies of hydrogenation and dehydrogenation catalysis: In the preliminary work, we could show that manganese catalysts are an interesting alternative to noble metal catalysts in the hydrogenation of C=O bonds (Angew. Chem. 2016, paper 1). Right now we don’t know how the catalytic cycle proceeds and how the activation of substrates takes place. We thus propose mechanistic studies, which also permit a more rational catalyst design. The obtained insight should be used for the hydrogenation of imines in the presence of hydrogenation sensitive functional groups. Beside hydrogenation we are interested in mechanistic aspects of the dehydrogenation, especially the role of the base.2. Novel (chiral) catalysts: Progress in manganese based hydrogenation and dehydrogenation catalysis is strongly linked with the development of novel catalysts. Thus, we plan the development of a novel (also chiral) catalyst class. Therefore, a simple and broadly variable ligand synthesis is applied. The novel catalysts are used comparative in a variety of reactions. With regard to enantioselective catalysis, for instance, the hydrogenation of imines is of interest. 3. Novel alcohol re-functionalization reactions: In our preliminary work, we could demonstrate a Mn-Ir analogy in dehydrogenative condensation reaction for the synthesis of aromatic N-heterocyclic compounds (2 x Angew. Chem. 2017, paper 2 and 3). Thus, the development of novel syntheses of heterocycles using manganese catalysts should be possible in the future. Beside the base-tunable Imine-amine synthesis, the development of a novel pyrimidine and imidazole synthesis is proposed. Preliminary work support the feasibility of them.