超分子組立催化アザプリンサイクリングにおける拘束結合による新しい反応モードの実現
David M Kaphan1, F Dean Toste1, Robert G Bergman1
1Chemical Sciences Division, Lawrence Berkeley National Laboratory and Department of Chemistry, University of California, Berkeley, California 94720, United States.
Journal of the American Chemical Society
|July 16, 2015
まとめ
超分子組立1は,溶液中の反応を上回る,ヒドリド移転によるユニークなアザ-プリンス循環を可能にします. この触媒的模倣は反応経路と製品の選択性に対する驚くべき制御を示しています.
科学分野:
- 超分子化学
- 有機合成
- キャタリシス
背景:
- 超分子化学は 機能的なシステムを創造するために 自己組織化分子を使用します
- 酵素ミミックは,自然酵素の触媒効率と選択性を複製するように設計されています.
- Aza-Prinsの循環は,窒素を含むヘテロサイクルを形成する有機合成における重要な反応である.
研究 の 目的:
- 超分子触媒による二分子アザ-プリンス循環のメカニズムを調査する.
- 反応経路を制御する 超分子腔の役割を理解する
- 選択的触媒を模倣する酵素としての超分子システムの可能性を探求する.
主な方法:
- 特定の超分子組成を用いたカタリシス (1).
- 反応速度と速度を制限するステップを決定する運動分析
- 反応メカニズムを追跡するための同位体ラベル研究
- 超分子腔内の反応性の比較と大量溶液の比較
主要な成果:
- 超分子組立1は,予期せぬトランスアニュラルの1,5-ヒドリド移転でアザ-プリンスサイクルを触媒化する.
- 触媒効果は,超分子腔内の圧縮結合に起因する.
- 大量溶液における反応性は,組成1によって与えられる選択性を強調する,直角的な経路を示している.
- イミニウムイオンの封じ込めは,ヒドリド転送メカニズムをサポートする速度制限ステップとして識別されます.
結論:
- 超分子組成1は,希少なヒドリド伝達経路を促進する,非常に効果的な酵素模倣剤として作用する.
- この研究は,超分子封じ込めによる製品の選択性における極端な差異を示しています.
- この研究は 複雑な有機変異を制御する 超分子化学の力を示しています
関連する概念動画
Cycloaddition Reactions: Overview
3.8K
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.
3.8K
Thermal and Photochemical Electrocyclic Reactions: Overview
3.2K
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.
3.2K
Cycloaddition Reactions: MO Requirements for Thermal Activation
5.1K
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.
5.1K
Pericyclic Reactions: Introduction
11.0K
Pericyclic reactions are organic reactions that occur via a concerted mechanism without generating any intermediates. The reactions proceed through the movement of electrons in a closed loop to form a cyclic transition state, where rearrangement of the σ and π bonds yields specific products.
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic...
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic...
11.0K
Woodward–Hoffmann Selection Rules and Microscopic Reversibility
4.2K
Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...
4.2K
Photochemical Electrocyclic Reactions: Stereochemistry
2.4K
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
2.4K


![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)