选择性兴奋状态光反应由一种合结合敏化剂控制
Kazimer L Skubi1, Jesse B Kidd1, Hoimin Jung2,3
1Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States.
Journal of the American Chemical Society
|November 1, 2017
概括
研究人员开发了一种用于三重状态光反应的新性光催化剂. 这种催化剂通过利用结和 π-π 相互作用来合成分子,从而达到高的选择性,以实现精确的立体化学控制.
科学领域:
- 光化学合成 光化学合成
- 有机金属化学 有机金属化学
- 立体化学是一种立体化学.
背景情况:
- 在电子激发状态下控制立体化学是光化学合成的一个重大挑战.
- 现有的高enantioselectivity三重态光反应的催化系统是有限的.
- 状光催化为非对称合成提供了一个有前途的途径.
研究的目的:
- 为三重状态光反应开发一种高效的性光催化剂.
- 为了实现高的enantioselectivity在合成的前性诺.
- 通过基质组织在性催化环境中研究立体感应的机制.
主要方法:
- 一种基于过渡金属的新性光催化剂的设计和合成.
- 利用结和π-π相互作用来招募和组织基质.
- 采用德克斯特能量传输来实现高效的能量传输和立体感应.
- 通过连接物修饰优化催化剂结构.
主要成果:
- 开发的性光催化剂在三重状态光反应中表现出了卓越的有效性.
- 通过精确组织前性诺基底物,可以实现高的异能选择性.
- 在催化剂的性环境中观察到高效的德克斯特能量传输和立体感应.
- 与有机光催化剂相比,催化剂在显著较低的负载下实现了高反体过剩.
结论:
- 一种新的性光催化剂使三重状态光反应中的有效立体化学控制成为可能.
- 催化剂的设计,利用特定的非共价相互作用,是其高性能的关键.
- 该系统为非对称光化学合成提供了一种更高效和潜在的成本效益的方法.
![[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)
相关概念视频
01:26Photochemical Electrocyclic Reactions: Stereochemistry
2.3K
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
2.3K
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.6K
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
2.6K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
3.1K
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.
3.1K
02:35Regioselectivity of Electrophilic Additions-Peroxide Effect
11.1K
In the presence of organic peroxides, the addition of hydrogen bromide to an alkene yields the isomer that is not predicted by Markovnikov’s rule. For example, the addition of hydrogen bromide to 2-methylpropene in the presence of peroxides gives 1-bromo-2-methylpropane. This addition reaction proceeds via a free radical mechanism, which reverses the regioselectivity. The free radical reaction mechanism involves three stages: initiation, propagation, and termination.
11.1K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.9K
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...
3.9K
01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
2.8K
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.
2.8K