在四碳酸催化反应中C-H插入,尽管有分裂的动态趋势:对反应效率和催化剂设计的影响
Wentao Guo1, Stephanie R Hare1, Shu-Sen Chen1
1Department of Chemistry, University of California, Davis, California 95616, United States.
Journal of the American Chemical Society
|September 13, 2022
概括
Rh催化的C-H插入反应可以产生多个产物. 最初的分子动力学模拟揭示了催化剂设计,特别是使用更大的腔和特定的替代剂,如何控制对所需β-lactones的选择性.
科学领域:
- 有机化学 有机化学
- 计算化学计算化学
- 催化剂是一种催化剂.
背景情况:
- 催化C-H插入反应对于合成β-乳酸至关重要.
- 这些反应经常面临过渡后状态分叉的挑战,导致不可预测的产品选择性.
- 传统的过渡状态理论努力解释这种复杂的反应路径中的选择性.
研究的目的:
- 使用ab initio分子动力学模拟来预测和合理化Rh催化C-H插入反应中的产品选择性.
- 研究催化剂结构,包括固体效应和弱相互作用在控制反应结果中的作用.
- 为β-乳合成催化剂的合理设计提供理论框架.
主要方法:
- 使用ab initio分子动力学模拟来建模反应路径并预测产品分布.
- 应用能量分解分析和非共价相互作用分析来理解催化剂-基质相互作用.
- 比较小型和大型催化剂活性位点的行为.
主要成果:
- 最初的分子动力学模拟成功预测了产品选择性,克服了传统过渡状态理论的局限性.
- 涉及2-甲替代物的弱相互作用被确定为影响选择性的关键.
- 较大的催化剂活性位点通过促进片段重组证明了克服动态偏好的碎片化途径的能力.
结论:
- 催化剂的设计,特别是活性部位腔的尺寸和特定的替代剂,是控制Rh催化β-乳形成的选择性的关键.
- 分子动力学模拟提供了一种强大的方法来理解和合理化复杂的反应动力学和选择性.
- 这些发现为通过C-H插入设计更有效和更有选择性的β-乳合成催化剂提供了基础.
相关概念视频
Radical Reactivity: Intramolecular vs Intermolecular
1.8K
Radical reactions can occur either intermolecularly or intramolecularly. In an intermolecular radical reaction, a nucleophilic radical adds to an electrophilic alkene or vice versa. In such reactions, the radical and generally the alkene, which is also called the radical trap, are two different molecules. Additionally, for such intermolecular reactions to occur, the radical trap must be active, present in an excess concentration, and the radical starting material must have a weak...
1.8K
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
10.4K
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
10.4K
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.4K
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
3.4K
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
3.9K
The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.
3.9K
Radical Reactivity: Concentration Effects
1.5K
In a radical reaction, the concentration of starting materials governs the selectivity of a radical. For example, the reaction between an alkyl halide and an alkene, in the presence of tin hydride and AIBN, begins with the generation of a tin radical. The generated radical then abstracts halogen from the alkyl halide, producing an alkyl radical. This alkyl radical can either react with tin hydride, yielding an alkane, or add to an alkene, generating a nitrile-stabilized radical, eventually...
1.5K
Reduction of Alkenes: Catalytic Hydrogenation
12.4K
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
12.4K


