Development of Synthetic Methods for the Late-Stage Modification of Synthetic Intermediates: The Arene-Limited Nondirected C–H Activation of Arenes and the Direct C–H Activation of Aliphatic Carboxylic Acids

向基于可再生资源的可持续能源系统和化学价值链的过渡，创造了对更高效和资源节约的合成方法的持续需求，以满足全球对复杂有机分子（如药物、农药或功能材料的一部分）日益增长的需求。在这种情况下，用于碳-氢键的直接官能化的方法是非常有吸引力的，因为它们具有缩短合成胭脂和减少废物产生的潜力。然而，这种方法的开发具有挑战性，因为待官能化的C-H键在化学上非常稳定，因此是惰性的。同时，典型的有机分子具有各种不同的C-H键，使得在这样的过程中选择性几乎是微不足道的。由于C-H官能化方法的巨大潜力仍然未得到充分开发，因此此类方法处于大量研究工作的中心。本项目的目的是研究钯催化的芳香族和脂肪族底物的C-H活化的策略，目前没有合适的方法具有足够的反应性和选择性。对于芳香族C-H键的官能化，我们最近发现了基于使用两个互补配体的催化剂体系。我们的目标是使用并在概念上进一步开发这种方法，用于可用作限制试剂的无导向基团芳香族底物的官能化。为了使脂肪族底物官能化，游离羧酸被用作高度吸引的定向基团。在小组先前研究的基础上，我们的目标是开发新的配体和反应条件，以实现这一目标。总的来说，这些研究有望为复杂有机分子的功能化提供合成上有用的方法，这有助于解决上述社会挑战。

The transition to sustainable energy systems and chemical value chains based on renewable resources creates a continued demand for ever more efficient and resource saving synthetic methods, in order to meet the growing global demand for complex organic molecules such as drugs, pesticides, or parts of functional materials. In this context methods for the direct functionalization of carbon-hydrogen bonds are very attractive, since they hold the potential to shorten synthetic rouges and reduce waste production. Such methods are, however, challenging to develop, since the C–H bonds to be functionalized are chemically very stable and thus inert. At the same time typical organic molecules possess a variety of different C–H bonds, such that selectivity is all but trivial in such processes. Due to the substantial potential of C–H functionalization methods that still remains underexploited, such methods are at the center of substantial research efforts. The aim of this project is to study strategies for the palladium-catalyzed C–H activation of aromatic and aliphatic substrates, for which no suitable methods with sufficient reactivity and selectivity are currently available. For the functionalization of aromatic C–H bonds, we have recently discovered a catalyst system based on the use of two complementary ligands. We aim to use and conceptually further develop this approach for the functionalization of directing group-free aromatic substrates that can be employed as the limiting reagent. To functionalize aliphatic substrates, free carboxylic acids are to be used as highly attractive directing groups. Building upon previous studies in the group we aim to develop novel ligands and reaction conditions in order to achieve this goal. Overall, these studies are expected to deliver synthetically useful methods for the functionalization of complex organic molecules, which can contribute to addressing the abovementioned societal challenges.