Tailor-made well-defined copper nitrenes for catalytic asymmetric C-H amination and aziridination

氮烯是开壳的低价化合物，由于氮烯氮的缺电子构型，其特别具有反应性。氮烯可以例如由合适的金属络合物和有机叠氮化物或亚氨基碘烷制备，其中金属被氧化并且氮烯的化合价通过金属-氮烯键饱和。这种金属氮烯被认为是催化直接胺化和氮烯转移到不饱和有机底物和杂原子的关键物种。特别地，末端氮烯的出现被认为是所述反应的反应性的决定性因素。到目前为止，只有少数终端铜氮烯已被确定。通过专门操纵它们的电子性质，可以增加金属氮烯的反应性，其中特殊的配体设计在这里是决定性的。通过XRD、XAS、ESR、拉曼和UV/维斯光谱研究，可以从实验上获得金属氮烯的价电子和成键比。此外，电子性质可以在理论上建模的物种的识别，从而可以模拟的光谱特性。在氮烯介导的催化中，迄今为止主要是过渡金属（Cu、Pd、Fe、Ru、Ag、Ir、Rh、Co、Mn）发挥作用;由于大量的可用性和低毒性，铜上级许多过渡金属。最有效的铜催化剂需要苛刻的热条件。然而，由于含金属的叠氮化合物和亚氨基碘烷溶液具有爆炸性，因此必须不惜一切代价避免加热，并且出于安全原因，永远不会获得工业应用。此外，尽管对金属氮烯的催化研究已经有很多年了，但很少有功能氮烯体系和功能催化剂之间的一致性。在以前的研究中，我们能够表明，双（吡唑基）甲烷稳定的铜氮烯配合物存在的单线态，这是非常有利的区域和对映体选择性的胺化和氮杂环丙烷化。我们现在想通过手性改变双（吡唑基）甲烷并将这个复杂的家族扩展到恶唑啉来进一步发展这个概念。定制配体的可能性，连同来自光谱表征和动力学以及催化研究的反馈，允许具有可调性质的反应性金属氮烯的有针对性的设计。此外，还将开发新的氮烯来源。一个重要的焦点也是潜在的相关性的各自的自旋状态与所观察到的反应性。

Nitrenes are open-shell, low valent compounds, which are particularly reactive due to the electron deficiency configuration at the nitrene nitrogen. Nitrenes can be produced, for example, from suitable metal complexes and organic azides or iminoiodinanes, whereby the metal is oxidised and the valency of the nitrene is saturated by metal-nitrene bonds. Such metallonitrenes are considered key species for catalytic direct amination and nitrene transfer to unsaturated organic substrates and heteroatoms. In particular, the occurrence of terminal nitrenes is considered a decisive factor for the reactivity of the reactions addressed. So far, only a few terminal copper nitrenes have been characterised. By specifically manipulating their electronic properties, it is possible to increase the reactivity of metal nitrenes, whereby the special ligand design is decisive here. The valence electrons and bonding ratios of the metal nitrenes are experimentally accessible via XRD, XAS, ESR, Raman and UV/Vis spectroscopic investigations. In addition, the electronic properties can be modelled theoretically for the identification of the species and thus the spectroscopic properties can be simulated. In nitrene-mediated catalysis, mainly transition metals (Cu, Pd, Fe, Ru, Ag, Ir, Rh, Co, Mn) have played a role so far; due to the large availability and low toxicity, copper is superior to many transition metals. The most effective copper catalysts require harsh thermal conditions. However, the heating of metal-containing azide and iminoiodinane solutions must be avoided at all costs due to their explosive nature and will never find industrial application for safety reasons. Furthermore, although there have been catalytic studies on metal nitrenes for many years, there is rarely a congruence between a functional nitrene system and functional catalyst. In previous studies, we were able to show that bis(pyrazolyl)methane-stabilised copper-nitrene complexes exist as singlet, which is very advantageous for the regio- and enantioselectivity of aminations and aziridinations. We now want to develop this concept further by chirally varying the bis(pyrazolyl)methanes and also extending this complex family towards oxazolines. The possibility to tailor the ligands, together with feedback from spectroscopic characterisation and kinetic as well as catalytic studies, allows a targeted design of reactive metal-nitrenes with tunable properties. In addition, new nitrene sources are to be developed. An important focus is also the potential correlation of the respective spin states with the observed reactivity.