Artificial photosynthesis strategies for synthesis: Combined photoredox and transition metal-catalysed transfer hydrogenation of C-C multiple bonds

人工光合作用合成策略：结合光氧化还原和过渡金属催化的 C-C 多重键转移氢化

• 批准号: EP/V048961/1
• 负责人: Xacobe Cambeiro
• 金额: $ 25.8万
• 依托单位: University of Greenwich
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FV048961%2F1
• 关键词: Artificial; photosynthesis; strategies; synthesis; Combined

The feasibility of chemical reactions is generally governed by the existence of a sufficient thermodynamic driving force pushing them. When performing sequences of reactions to prepare compounds of interest, this driving force is ensured by using in each step highly reactive small molecule reactants with a high energy contents, and the availability and procedence of such reactants determine the limits of how practical and sustainable a chemical process can be. Illustrative examples are oxidations and reductions, two of the main categories in which we classify chemical reactions. In the case of oxidation reactions, molecular oxygen can be used an ideal oxidant, since it is abundant and innocuous and in ideal conditions it can be consumed to produce only water as a by-product. Similarly, we could conceive using water as an ideal reductant, which would result in production of only oxygen as by-product. However, this faces the problem of water not being a good reductant or, in other words, lacking the thermodynamic driving force needed to push the reaction. Instead, the most common reductant used for organic compounds is molecular hydrogen, which is not found in nature and is instead produced in an overwhelming majority from fossil fuels in a process that releases enormous amounts of carbon dioxide.Remarkably, photosynthetic organisms use water as the reductant in the fixation of carbon dioxide to form carbohydrates and release molecular oxygen, with sunlight providing the required energy. Taking inspiration from this, in this proposal we aim to develop an 'artificial photosynthesis' approach for the reduction of certain types of organic compounds of industrial importance -namely, alkenes and alkynes. To do this, we will need to develop systems where two catalysts operate in a concerted manner, with one using the energy from light to oxidise water (forming oxygen and providing the 'reductive power') and the other reducing the organic compound. Catalysts are already known capable of performing the first of these roles, and in this project we will develop the second, thus bridging the key gap to enable true artificial photosynthesis reactions in organic chemistry.This investigation will result in more sustainable methods for reduction of alkenes and alkynes which, importantly, are among the largest scale organic reactions performed in chemical industry. Thus, success in this project will contribute towards the development of a more sustainable chemical industry in general, reducing its dependence on the use of fossil sources of carbon. Also, this investigation will produce valuable information on the mechanistic manifolds involved, thus providing facilitating the discovery of other efficient and sustainable reactions in the future.

化学反应的可行性通常取决于是否存在足够的热力学驱动力来推动它们。当进行一系列反应以制备感兴趣的化合物时，通过在每一步中使用高能量含量的高活性小分子反应物来确保这种驱动力，而这些反应物的可用性和程序决定了化学过程的实用性和可持续性的极限。氧化和还原就是一个很好的例子，这是我们对化学反应进行分类的两个主要类别。在氧化反应的情况下，分子氧可以作为理想的氧化剂，因为它是丰富和无害的，在理想的条件下，它可以被消耗，只产生水作为副产物。同样地，我们可以设想用水作为理想的还原剂，这将导致只生产氧气作为副产物。然而，这面临着水不是一个好的还原剂的问题，换句话说，缺乏推动反应所需的热力学驱动力。相反，用于有机化合物的最常见还原剂是分子氢，它不存在于自然界中，而是绝大多数由化石燃料产生，这一过程会释放大量的二氧化碳。值得注意的是，光合生物利用水作为二氧化碳固定的还原剂，形成碳水化合物并释放分子氧，而阳光提供所需的能量。受此启发，在这个提案中，我们的目标是开发一种“人工光合作用”方法，以减少某些类型的工业重要有机化合物，即烯烃和炔烃。要做到这一点，我们需要开发两种催化剂协同工作的系统，其中一种利用光的能量氧化水（形成氧气并提供“还原力”），另一种则还原有机化合物。目前已知的催化剂能够发挥第一种作用，在这个项目中，我们将开发第二种作用，从而弥合有机化学中实现真正的人工光合作用反应的关键差距。这项研究将产生更可持续的方法来减少烯烃和炔烃，重要的是，这是化学工业中规模最大的有机反应之一。因此，这个项目的成功将有助于发展更可持续的化学工业，减少其对使用矿物碳源的依赖。此外，这项调查将产生有关所涉及的机械流形的宝贵信息，从而为将来发现其他有效和可持续的反应提供便利。