Hemicarcerand ligands for the systematic investigation of sigma-alkane complexes

烷烃的选择性功能化是一个具有当代重要性的领域--其动机是希望在有机合成中有效和有效地利用这些廉价和丰富的碳氢化合物，并将其用作化学工业的原料。这样的目标受制于烷烃的化学惰性，而这些惰性是由组成强烈的C-C和C-H键赋予它们的。通过可溶过渡金属催化剂的作用，在克服这些限制方面取得了进展，尽管在大规模实际实施方面仍存在许多实质性挑战。事实证明，关键的绊脚石之一是建立这些过程的基本机械性化学：由于它们的瞬变和极具活性的性质，烷烃活化过程中涉及的金属中间体极难使用传统方法进行研究。这些信息构成了合理开发有用催化体系的重要先决条件知识。拟议的研究项目涉及开发一种史无前例的超分子方法，用于系统地研究过渡金属介导的烷烃，特别是难以捉摸的西格玛-烷烃中间体的活化。这种方法需要制备和使用定义明确的大分子空穴和配体，它们通过将烷烃包裹在大分子内部来促进和稳定过渡金属西格玛-烷烃络合物的形成。在这些超分子体系中加入烷烃有效地绕过了与传统策略相关的有害问题，并允许有效地询问金属-烷烃相互作用。最终，这种方法将产生一个明确的基础化学体系，这将使人们对烷烃活化方法的理解发生一步变化。

The selective functionalisation of alkanes is an area of contemporary importance - motivated by the desire to make efficient and effective use of these inexpensive and abundant hydrocarbons in organic synthesis and as feedstocks for the chemical industry. Such objectives are encumbered by the chemical inertness of alkanes, conferred upon them by the strong constituent C-C and C-H bonds. Through the action of soluble transition metal catalysts, progress has been made in overcoming these limitations although many substantial challenges remain for large-scale practical implementation. One of the key stumbling blocks has proven to be establishing the fundamental mechanistic chemistry of these processes: encumbered by their transient and extremely reactive nature, metal-based intermediates involved in alkane activation processes are exceedingly difficult to investigate using conventional approaches. Such information constitutes vital prerequisite knowledge for the rational development of useful catalytic systems.The proposed research project involves the development of an unprecedented supramolecular approach for systematically investigating the transition metal mediated activation of alkanes, in particular elusive sigma-alkane intermediates. The approach entails the preparation and use of well-defined macromolecular cavitand ligands, which both promote and stabilise the formation of transition metal sigma-alkane complexes through encapsulation of the alkane within the interior of the macromolecule. The inclusion of the alkanes within these supramolecular systems effectively circumvents detrimental problems associated with conventional strategies and allows effective interrogation of the metal-alkane interaction. Ultimately, this approach will generate a definitive body of fundamental chemistry that will enable a step change in understanding of alkane activation methods.