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世界各地数以千计的科学家的工作至关重要。特别是，选择性地形成碳-碳键是几乎所有合成努力的核心，对明天的制药、农用化学品和材料的组装至关重要。金属催化的交叉偶联反应已经被开发出来用于C-C键的形成，现在每个化学实验室都经常进行这种反应。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，大多数交叉耦合是由铂族金属(例如，Ru、Rh、Pd、Ir和铂)调节的，这些昂贵金属的供应面临风险，因此它们的使用不可持续。正是在未来不确定的背景下，对无金属交叉偶联方法的探索吸引了合成界的注意力。世界领先的合成科学家现在都有一个共同的愿景，即化学社区对铂族金属的依赖程度降低。芳基硫盐是备受瞩目的下一代交叉偶联伙伴，因为它们易于使用，并且对金属和光活化都具有反应性。在简化的净C-H官能化过程中，从未被取代的芳烃中可以很容易地在无金属的条件下从没有取代的芳烃中获得具有良好位置选择性的硫盐。我们最近在芳烃和芳烃自由基陷阱的无金属C-H/C-H交叉偶联中利用了硫盐的光化学活化。现在，我们将与阿斯利康的同事合作，通过扩展可用于光催化的硫酸盐和捕捉剂系列，并通过形成电子供体-受体(EDA)络合物来研究硫盐的光活化，从而将硫酸盐的光化学远远扩展到当前最先进的水平。我们的研究将提供一套在一个反应容器中运行的无金属耦合过程，并将简单的原料化学品转化为高价值的产品。我们的研究映射到以下EPSRC研究领域-合成有机化学、催化、化学反应动力学和机理、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的制造未来、医疗保健技术、能源和物理科学主题。

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.