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

胺在包括农业和制药部门在内的各种行业中发挥着重要作用。虽然胺可以很容易地在实验室规模上合成，但这些合成方案通常对工业没有吸引力，通常是由于前体的安全性问题或原子效率低下的方法。相比之下，加氢胺化（在不饱和底物（如烯烃或炔烃）上添加氨）是一种有吸引力的方法，用于以可持续的方式合成增值化学品，如化肥。尽管该方法具有吸引人的性质，但氨是一种具有挑战性的底物，并且迄今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加氢胺化，因为它们倾向于与氨形成Werner络合物，这妨碍了N-H键活化。相比之下，主族系统是过渡金属的有吸引力的替代品，因为它们在地球上更丰富，不太可能形成不反应的氨加合物，但它们的催化行为较少被探索。显然，开发可行的加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小组合成了含有P-Ga双键的新物种（称为磷丙二烯）。它们作为受抑刘易斯对（FLP）和激活各种N-H键（包括氨键）的能力也得到了证明;这些加入了大约十几个使用主基系统激活单位点N-H键的例子。该项目的目标是利用这种不寻常的反应性与过渡金属的协同催化，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族元素多重键的新物种，并研究此类化合物在小分子活化反应中的行为，特别侧重于胺。此外，该项目将探索这些新化合物在不饱和物质（如烯烃和炔烃）的催化氢胺化反应中的可行性。传统上，小分子活化主要限于过渡金属。尽管这些元素在催化中具有广泛的应用，但这并不延伸到氨的催化加氢胺化;目前仅已知基于Au（I）的单一实例。相比之下，许多主族化合物已被证明可以化学计量地活化氨，但主族体系的催化作用仅限于碱土金属，并且仅限于取代更多的胺。本研究的目的是探索磷丙二烯在催化氢胺化反应中的新特性。该项目福尔斯属于EPSRC催化研究领域，直接有助于制造未来和物理科学的研究主题。

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.