[2+2] 酸化性可視光光触媒によるサイクル添加 [2+2]
Michael A Ischay1, Zhan Lu, Tehshik P Yoon
1Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA.
Journal of the American Chemical Society
|June 10, 2010
まとめ
ルテニウムトリス (((ビピリジン)) (Ru (((bpy) (((3) (((2+)) は,電子が豊富なオレフィンと,電子が欠けているオレフィンの両方の [2+2]サイクロアディションを効率的に触媒化する. この多用途の光触媒は,可視光を用いたストレントリング合成を可能にします.
科学分野:
- 有機化学 オーガニック・ケミストリー
- フォトケミストリー フォトケミストリー
- カタリシス カタリシス カタリシス
背景:
- 光化学反応は,サイクロブータンなどのストレントリングシステムを合成するのに価値があります.
- ルテニウムトリス (((ビピリジン)) (Ru (((bpy) (((3) (((2+)) は,電子欠乏オレフィンを含む [2+2]サイクロアディションの効果的な光触媒として以前に確立されています.
研究 の 目的:
- 電子に富んだオレフィンの [2+2]サイクル添加のための光触媒としてのRu(bpy) ((3) ((2+) の有効性を実証する.
- 有機合成におけるRu(bpy) ((3) ((2+) の汎用的な光電気化学的性質を強調する.
主な方法:
- Ru ((bpy) ((3) ((2+)) の存在下での可視光照射を用いた.
- 電子が豊富なオレフィンの [2+2] サイクル添加反応を研究した.
- 1電子の還元または酸化のための光触媒の光電気化学的能力を活用しました.
主要な成果:
- Ru (((bpy) (((3) ((2+) は,電子が豊富なオレフィンの [2+2]サイクル添加を効果的に触媒化する.
- 光触媒は,単電子還元経路または酸化経路を通じて反応を促進することによって,多用途性を示します.
結論:
- Ru (((bpy) (((3) ((2+) は,電子欠乏性オレフィンと電子豊富なオレフィンの両方の [2+2]サイクロアディションのための汎用的な光触媒です.
- これは,可視光光化学を介してストレートリングシステムを構築する Ru (((bpy) (((3) ((2+) の有用性を拡張します.
関連する概念動画
Cycloaddition Reactions: MO Requirements for Photochemical Activation
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.
Cycloaddition Reactions: Overview
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.
Cycloaddition Reactions: MO Requirements for Thermal Activation
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.
Photochemical Electrocyclic Reactions: Stereochemistry
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
Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
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.
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