Computational studies of organic reactions

选择性反应是在多种可能的反应途径中，一种途径占主导地位的反应。每个途径都与一个过渡态相关，然而一些过渡态比其他过渡态更有利且能量更低。最低能量的过渡态对应于最有利的反应途径，因此导致选择性反应的主要产物。选择性反应，无论是区域选择性的，对映体选择性的还是非对映体选择性的，由于其在工业，研究和环境方面的广泛影响，在化学中具有重要意义。例如，不对称催化允许高度选择性地形成特定化合物的纯所需对映异构体。这通常比相应的非选择性方法更便宜，并且允许更好的产率。因此，可以减少废物量，同时提高选择性化学合成和工艺的效率和便利性。理解反应背后的选择性依赖于对反应机理和相关过渡态的了解，以及决定每个过渡态能量的潜在因素。这样的反应机制的见解可以通过彻底探索他们的势能面，一个数学函数，给出了系统的能量作为一个函数的所有原子的位置在它里面。反应的基态物种，即反应物，中间体，或产品，是由势能面上的最小值表示，而过渡态是由鞍点表示。存在多种计算方法可用于探索反应的势能面，例如密度泛函理论（DFT），一种仅基于其电子密度导出系统的能量的从头算量子力学方法，以及使用经典力学描述分子的分子力学。因此量子力学计算，例如使用DFT进行的那些，可以用来定位和确定过渡态的能量，从而阐明反应机理。这种详细的见解，使改进的选择性催化剂的合理设计，现有的催化剂应用到新的选择性反应，并调整现有的选择性过程，以提高产量和efficient.The本研究的基础涉及使用计算方法，如DFT和分子力学，调查各种选择性反应的机理细节。芳烃的过渡金属催化的选择性C-H硼基化和有机催化的对映选择性羟醛缩合是两个这样的感兴趣的反应的例子。

A selective reaction is one where, of multiple possible reaction pathways, one pathway dominates. Each pathway is associated with a transition state, however some transition states are more favourable and lower in energy than others. The lowest energy transition state corresponds to the most favourable reaction pathway and hence leads to the major product of a selective reaction.Selective reactions, whether regio-, enantio- or diastereoselective, are of the significant interest in chemistry due to their widespread implications in both industry, research and on the environment. For example, asymmetric catalysis allows the highly selective formation of purely the desired enantiomer of a particular compound. This is often cheaper, and allows for much better yields, than corresponding unselective methods. Hence the amount of waste can be reduced while the efficiency and ease of selective chemical syntheses and processes can be improved.Understanding the selectivity behind a reaction relies on a knowledge of the reaction mechanism and relevant transition states, as well as the underlying factors that determine the energy of each transition state. Such insights into reaction mechanisms may be obtained by a thorough exploration of their potential energy surfaces, a mathematical function that gives the energy of the system as a function of the positions of all the atoms within it. The ground state species of a reaction, i.e. reactants, intermediates, or products, are represented by minima on the potential energy surface, whilst transition states are represented by saddle points. A variety of computational methods exist that can be used to explore the potential energy surface of a reaction, for example density functional theory (DFT), an ab initio, quantum mechanical method which derives the energy of a system based only on its electron density, and molecular mechanics, which uses classical mechanics to describe molecules.Hence quantum mechanical calculations, such as those carried out using DFT, can be used to locate and determine the energy of transitions states and hence elucidate reaction mechanisms. Such detailed insights enables the rational design of improved selective catalysts, the application of existing catalysts to new selective reactions, and the tuning of existing selective processes to improve yield and efficiency.The basis of this research involves the use of computational methods, such as DFT and molecular mechanics, to investigate the mechanistic details of a variety of selective reactions. Transition-metal catalysed selective C-H borylation of arenes and organocatalyzed enantioselective aldol condensations are two such examples of reactions of interest.