Photoactivation of sulfonium salts in transition metal-free formal C-H/C-H-type couplings

合成化学是推动科学技术进步的引擎，因为人造分子和材料对全世界成千上万科学家的工作至关重要。特别是，碳碳键的选择性形成是几乎所有合成努力的核心，对未来的药品、农用化学品和材料的组装至关重要。金属催化的交叉偶联已经发展为碳-碳键的形成，现在在每个化学实验室常规进行。交叉耦合技术对科学和社会的积极影响是显著的。不幸的是，大多数交叉偶联是由铂族金属（如钌、铑、钯、铱和铂）介导的，这些昂贵金属的供应面临风险，因此使它们的使用不可持续。在不确定的未来背景下，寻找无金属交叉耦合的方法已经抓住了合成界。世界领先的合成科学家们现在有一个共同的愿景，那就是建立一个不那么依赖铂族金属的化学社区。芳基磺酸盐是备受瞩目的下一代交叉偶联伙伴，因为它们易于使用和对金属和光活化的反应性。在无金属条件下，通过流线型净C-H功能化过程，可以很容易地从未取代的芳烃中获得磺化盐，具有优异的位点选择性。我们最近开发了在芳烃和芳烃自由基陷阱的无金属C-H/C-H交叉偶联中磺化盐的光化学活化。现在，通过与阿斯利康的同事合作，我们将通过扩展可用于光催化的磺化盐和捕获剂的组合，并通过电子供体-受体（EDA）复合物的形成来研究磺化盐的光活化，从而将磺化盐的光化学扩展到目前最先进的水平。我们的研究将提供一套无金属偶联工艺，在一个反应容器中操作，并将简单的原料化学品转化为高价值产品。我们的研究涉及以下EPSRC研究领域-合成有机化学，催化，化学反应动力学和机制，制造技术，化学生物学和生物化学，以及能源应用材料-跨越EPSRC制造未来，医疗保健技术，能源和物理科学的主题。

Synthetic chemistry is the engine that drives the advance of science and technology as man-made molecules and materials are vital to the work of thousands of scientists around the world. In particular, the selective formation of C-C bonds lies at the heart of almost any synthetic endeavour and is crucial for the assembly of tomorrow's pharmaceuticals, agrochemicals and materials. Metal-catalysed cross-coupling has been developed for C-C bond formation and is now routinely carried out in every chemistry laboratory. The positive impact of cross-coupling technology on science and on society has been remarkable. Unfortunately, the majority of cross-coupling is mediated by platinum group metals (e.g. ruthenium, rhodium, palladium, iridium and platinum) and the supply of these costly metals is at risk, thus making their use unsustainable. It is against the backdrop of an uncertain future that the search for methods for metal-free cross-coupling has gripped the synthetic community. The world's leading synthetic scientists now share a vision of a chemical community less reliant on platinum group metals. Arylsulfonium salts are high profile, next generation cross-coupling partners due to their ease of use and reactivity towards both metal and photoactivation. Sulfonium salts can be easily obtained under-metal-free conditions, with excellent site-selectivity, from unsubstituted arenes, in streamlined net C-H functionalisation processes. We have recently exploited the photochemical activation of sulfonium salts in a metal-free C-H/C-H cross-coupling of arenes and arene radical traps. Now, in collaboration with colleagues at AstraZeneca, we will extend the photochemistry of sulfonium salts far beyond the current state-of-the-art by expanding both the suite of sulfonium salts and trapping agents available for photocatalysis, and investigating the photoactivation of sulfonium salts through electron donor-acceptor (EDA) complex formation. Our studies will deliver a suite of metal-free coupling processes that operate in one reaction vessel and convert simple feedstock chemicals to high-value products.Our studies map on to the following EPSRC Research Areas - Synthetic Organic Chemistry, Catalysis, Chemical reaction dynamics and mechanisms, Manufacturing Technologiues, Chemical Biology and Biological Chemistry, and, Materials For Energy Applications - that straddle the EPSRC themes of Manufacturing the Future, Healthcare Technologies, Energy, and Physical Sciences.