Hydrophosphination Catalysis Using Low-Coordinate Iron Complexes

有机磷化合物是化学中最重要的物种之一，推动着医药、金属提取、核燃料加工、润滑剂、农用化学品、材料和超分子化学等领域的重大进展。它们作为过渡金属配体的广泛应用支撑了许多现代均相催化过程，例如在金属催化的交叉偶联、烯烃歧化和C-H活化反应中。传统的磷化氢合成路线往往表现出较差的官能团耐受性、副产物形成，并使用大量的步骤，包括化学计量的添加剂、有毒金属试剂和保护基团。这些限制导致了大量的浪费，这是原子经济的一个问题。氢磷化反应涉及到在不饱和键上添加P-H部分，并提供了100%原子效率的潜力，并有机会使用相对简单的起始材料在有机磷产品中产生显著的复杂性。特别是，C=X(X=O，N，S)键的氢磷酸化是将杂原子官能团引入到产品中的有效方法，但由于缺乏合适的催化络合物、竞争副反应和催化剂中毒，研究仍然很少。因此，利用这种反应作为一种方便的策略来使磷化合物杂化还没有被开发出来。在全球利用富含稀土和无毒金属进行化学合成的重大努力的推动下，我们建议提供一种新的方法来合成有机磷化合物，使用铁络合物作为异丁烯化合物氢磷化的前催化剂。值得注意的是，我们的配合物可以催化这种反应的新的插入途径，这是非常罕见的，通常很难控制。这些新的反应途径有能力开启新的反应和合成方法。我们将探索这种氢化磷化化学，并使用未开发的底物来提供新的有机磷化合物家族，并通过控制催化剂的结构和反应条件来开发一种合理的方法来控制反应性和区域选择性。这种化学将被用于合成特定的有机磷化合物，这种催化机理的阐明将为在新的催化反应中开发新的反应策略提供实验和理论数据。因此，除了一系列新的有机磷化合物外，这一研究方案还将提供丰富的基础知识，供学术界和工业界的研究人员使用。由于一系列非常不同的有机磷物种的广泛性质和潜在用途，这一研究方案有可能对广泛的学术和工业应用产生重大影响。我们预计，我们对氢化磷化催化的方法将影响一系列氢化元素化反应，并可能影响其他方法，如同系化、聚合和选择性齐聚反应。

Organophosphorus compounds are one of the most important species in chemistry, driving critical advances in areas such as medicine, metal extraction, nuclear fuel processing, lubricants, agrochemicals, materials and supramolecular chemistry. Their wide use as ligands to transition metals underpins many modern homogeneous catalytic processes, for example in metal-catalysed cross-coupling, alkene metathesis and C-H activation reactions. Classic synthetic routes to phosphines often display poor functional group tolerance, side product formation, and use a significant number of steps including stoichiometric amounts of additives, toxic metal reagents and protecting groups. These limitations lead to copious waste, representing a problem for atom economy. Hydrophosphination reactions involve the addition of a P-H moiety across an unsaturated bond, and offer the potential for 100% atom efficiency with the opportunity to generate significant complexity in the organophosphorus products using relatively simple starting materials. In particular, the hydrophosphination of C=X (X = O, N, S) bonds is a powerful way to introduce heteroatom functionality into products, but remains poorly explored due to the paucity of suitable catalytic complexes, competing side reactions and catalyst poisoning. Thus, the use of this reaction as a convenient strategy to heterofunctionalised phosphorus compounds has not been exploited. Driven by major global efforts towards chemical synthesis using earth-abundant and non-toxic metals, we propose to deliver a new approach for the syntheses of organophosphorus compounds using iron complexes as pre-catalysts for the hydrophosphination of heterocumulene compounds. Significantly, our complexes can catalyse novel diinsertion pathways for this reaction, which are very rare and usually difficult to control. These new reaction pathways have the power to unlock new reactions and synthetic methodologies. We will explore this hydrophosphination chemistry and use unexplored substrates to deliver new families of organophosphorus compounds and develop a rational approach to control reactivity and regioselectivity through the manipulation of the structure of the catalyst and the reaction conditions. This chemistry will be used to synthesise specific organophosphorus targets and the elucidation of the mechanisms for this catalysis will provide experimental and theoretical data to inform new reaction strategies that may be developed in new catalytic reactions. This research programme will thus deliver a wealth of fundamental knowledge in addition to a bank of new organophosphorus compounds, which will be made available to researchers in academia and industry.This research programme has the potential to have significant impact for a broad range of academic and industrial applications due to the extensive properties and potential uses of a range of very different organophosphorus species. We envisage that our approach to the catalysis of hydrophosphination will impact a range of hydroelementation reactions and may impact other methodologies such as homologation, polymerisation and selective oligomerisation reactions.