Acetate assisted C-H activation: A computational and experimental study

各种各样的复杂有机分子在从药品到塑料的广泛日常应用中非常重要。一般来说，这些分子的合成是从稍微简单的起始材料实现的。这种起始材料的关键特征是存在反应性官能团。通常这将是卤代基团，例如C-Cl键。然而，这种官能团的形成通常效率低下，并会产生对环境有害的废物-在这种情况下，氯化废物。原则上，理想的官能团是C-H键。含有C-H键的起始材料丰富且极其便宜，因此不需要任何浪费的预先操作。不幸的是，C-H键有一个巨大的缺点-它们通常非常不活泼。然而，我们已经发现了一种通过使用某些金属络合物与特定碱乙酸盐组合来增强C-H键的反应性的方法。初步研究表明，带正电荷的金属可以攻击C-H键，使其易于被乙酸盐裂解。这个过程的结果是通过形成新的金属-碳键来“激活”C-H键。一旦形成，金属-碳键是非常活跃的，并经历广泛的选择性转化，包括C-C键的形成，这将允许合成更复杂的有机分子。基于我们的新的金属促进的C-H活化偶联随后C-C键形成的催化方法将是非常有吸引力的，因为它既非常有效（避免浪费地形成其他反应性官能团）又环境友好（避免形成副产物）。在我们提出的工作中，我们的目标是了解我们观察到的容易的C-H键活化背后的基本化学。我们将使用计算模型和实验化学来精确地研究是什么因素促进了这一过程。一旦确定这些因素可以包括在设计的新催化剂的C-H活化。

A huge variety of complex organic molecules are important in a wide range of everyday applications - from pharmaceuticals to plastics. In general the synthesis of these molecules is achieved from somewhat simpler starting materials. A key feature of such startng materials is the presence of a reactive functional group. Often this will be a halogenated group, such as a C-Cl bond. However, the formation of such functional groups is often inefficient and generates environmentally damaging waste - in this case chlorinated waste.In principle, an ideal functional group would be a C-H bond. Starting materials containing C-H bonds are abundant and extremely cheap and so do not require any wasteful prior manipulation. Unfortunately, C-H bonds have one huge drawback - they are generally extremely unreactive. However, we have discovered a way to enhance the reactivity of C-H bonds by using certain metal complexes in combination with a particular base, acetate. Preliminary studies suggest that a positively charged metal can attack a C-H bond and make it susceptible to cleavage by acetate. The result of this process is to 'activate' the C-H bond by making a new metal-carbon bond. Once formed, metal-carbon bonds are very reactive and undergo a wide range of selective transformations, including the formation of C-C bonds that will allow the synthesis of more complicated organic molecules. A catalytic process based on our new metal-promoted C-H activation coupled followed by C-C bond formation would be extremely attractive as it is both extremely efficient (avoids wasteful formation of other reactive functional groups) and environmentally friendly (avoids the formation of byproducts). In our proposed work we aim to understand the fundamental chemistry that lies behind our observation of easy C-H bond activation. We shall use both computational modelling and experimental chemistry to investigate precisely what factors promote this process. Once identified these factors can be included in the design of new catalysts for C-H activation.