可见光驱动 [2 + 2] 在不和脂质中和CC键之间的光环添加
Hai-Fang Li1, Wenbo Cao1, Xiaoxiao Ma1
1State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments , Tsinghua University , Beijing 100084 , People's Republic of China.
Journal of the American Chemical Society
|January 30, 2020
概括
研究人员通过使用非共价复合体进行 [2 + 2] 光环添加实现了氧化环构造. 这种由可见光驱动的反应提供了一种与帕特诺-布奇反应不同的新途径.
科学领域:
- 有机化学
- 摄影化学
- 超分子化学
背景情况:
- 和碳酸的 [2 + 2] 光环添加对于合成氧乙至关重要.
- 目前的方法通常依赖于单个基板的紫外线激发.
- 在这种反应中,对非共价碳复合物的直接激发还没有得到充分的研究.
研究的目的:
- 调查非共价基碳化合物中的 [2 + 2] 光环添加.
- 探索可见光驱动的氧化形成.
- 为了阐明这种新反应的机制.
主要方法:
- 和不和脂之间的非共价复合物的表征.
- 这些复合物的可见光照射.
- 用光谱分析识别反应产物和中间体.
主要成果:
- 成功表征了和不和脂质的非共价复合物.
- 实现了第一个可见光诱导的 [2 + 2] 循环添加形成氧乙.
- 确定了一种涉及复合体内的电子转移的新机制,与帕特诺-布奇反应不同.
结论:
- 非共价复合物可以被可见光直接激发,形成氧乙.
- 这种方法提供了基板激发波长的独立性.
- 提供了新的合成策略来构建氧化.
相关概念视频
Cycloaddition Reactions: MO Requirements for Photochemical Activation
2.5K
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
2.5K
Photochemical Electrocyclic Reactions: Stereochemistry
2.1K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
2.1K
Cycloaddition Reactions: Overview
3.3K
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
3.3K
Cycloaddition Reactions: MO Requirements for Thermal Activation
4.1K
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.
4.1K
Thermal and Photochemical Electrocyclic Reactions: Overview
2.9K
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
2.9K
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
12.0K
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.
12.0K
![[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
