Synthesis of multiply bonded main-group compounds for small molecule activation reactions

胺在各种行业中发挥着重要作用，包括在农业和制药部门。尽管很容易在实验室规模合成胺，但这些合成方案通常对工业没有吸引力，通常是因为对前体的安全担忧或原子效率低下的方法。相比之下，氢胺化(在不饱和的底物上加成氨，如烯烃或炔烃)是以可持续的方式合成化肥等增值化学品的一个有吸引力的过程。尽管这一过程具有吸引力，但氨是一种具有挑战性的底物，到目前为止，还没有已知的催化剂可以将其用作原料。过渡金属催化剂通常不能实现氢胺化反应，因为它们倾向于与氨形成沃纳络合物，这排除了N-H键的活化。相比之下，主族系统是过渡金属的一个有吸引力的替代品，因为它们在地球上更丰富，不太可能形成非活性氨加合物，但它们的催化行为还没有得到很好的研究。显然，开发可行的氢胺化催化剂是降低胺合成成本和浪费的重要一步。最近，Goicoechea基团合成了含有P-Ga双键的新物种(称为磷酸没食子烯)。它们作为受挫的Lewis对(FLP)并激活各种N-H键的能力也已被证明，包括氨的N-H键；这些加入了使用主基系统激活单位N-H键的大约12个例子。该项目的目标是利用过渡金属在协同催化中的这种不同寻常的反应活性，为从廉价和广泛可用的氨原料合成胺底物铺平道路。该项目旨在合成含有第13/15族元素多键的新物种，并研究此类化合物在小分子活化反应中的行为，特别是胺类化合物。此外，该项目将探索这些新化合物在不饱和物种(如烯烃和炔烃)催化氢胺化反应中的可行性。传统上，小分子活化在很大程度上仅限于过渡金属。虽然这些元素在催化中有广泛的应用，但这并不延伸到氨的催化氢胺化；目前只有一个基于Au(I)的例子是已知的。相比之下，一些主族化合物已被证明能按化学计量比活化氨，但主族体系的催化作用仅限于碱土金属，而且只有更多的取代胺。本项目的目的是开发磷酸没食子烯在催化氢胺化反应中的新行为。该项目属于EPSRC催化研究领域，该领域直接对制造未来和物理科学研究主题做出贡献。

Amines play an important role in a variety of industries, including in agriculture and the pharmaceutical sector. Although amines can be easily synthesised on a laboratory scale, these synthetic protocols are often unattractive to industry, usually due to safety concerns with precursors or atom inefficient methodologies. By contrast, hydroamination (the addition of ammonia across an unsaturated substrate, such as an alkene or alkyne) is an attractive process for the synthesis of value-added chemicals such as fertilisers in an sustainable fashion. Despite the attractive nature of this process, ammonia is a challenging substrate, and to date there are no known catalysts which can use it as a feedstock. Transition metal catalysts typically fail in effecting hydroamination because of their propensity to form Werner complexes with ammonia which precludes N-H bond activation. In contrast, main-group systems are an attractive alternative to transition metals as they are more Earth-abundant and less likely to form unreactive ammonia adducts, but their catalytic behaviour is less well explored. Clearly, the development of a viable hydroamination catalyst is an important step towards reducing the cost and waste of amine synthesis. Recently, the Goicoechea group has synthesised novel species containing P-Ga double bonds (known as phosphagallenes). Their ability to act as a frustrated Lewis pair (FLP) and activate a variety of N-H bonds, including that of ammonia has also been demonstrated; these join the approximately dozen examples of single-site N-H bond activation using main-group systems. The goal of this project is to exploit this unusual reactivity in cooperative catalysis with transition metals, paving the way for the synthesis of amine substrates from inexpensive and widely available ammonia feedstocks. The project aims to synthesise novel species containing group 13/15 element multiple bonds and to study the behaviour of such compounds in small-molecule activation reactions, with a particular focus on amines. Further, the project will probe the viability of these novel compounds in catalytic hydroamination reactions of unsaturated species, such as alkenes and alkynes. Traditionally, small-molecule activation is largely limited to transition metals. Although these elements have widespread application in catalysis, this does not extend to the catalytic hydroamination of ammonia; only a single example based on Au(I) is presently known. By contrast, a number of main-group compounds have been shown to stoichiometrically activate ammonia, but catalysis with main-group systems is limited to the alkaline-earth metals and only with more substituted amines. The aim of this project is to exploit the novel behaviour of phosphagallenes in catalytic hydroamination. This project falls within the EPSRC Catalysis research area, which directly contributes to the Manufacturing the Future and Physical Sciences research themes.