カビタンドにおける選択的なマクロサイクル形成
Ji-Min Yang1, Yang Yu2, Julius Rebek1
1Skaggs Institute for Chemical Biology and Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States.
Journal of the American Chemical Society
|January 28, 2021
まとめ
カビタンドは水中の長鎖二アルデヒドの選択的なマクロサイクリングを可能にし,エントロピーの課題を克服します. この宿主-ゲスト系は 効率的なリング形成のために 生物学的触媒を模倣します
科学分野:
- 有機化学
- 超分子化学
- キャタリシス
背景:
- 線形前駆体のエンドツーエンドサイクルによるマクロサイクリングは,エントロピー的に不利である.
- 分子間反応はしばしば望ましい分子内循環と競合し,低収量と予測不可能な結果をもたらします.
- 伝統的なテンプレート作成方法は非効率で,テンプレートはホスト構造内でゲストとして機能します.
研究 の 目的:
- 溶液中の長鎖α,ω-二アルデヒドの分子内アルドール/脱水反応のための選択的方法の開発.
- 線形前駆体の形状を制御し,マクロサイクライゼーションを好むために,宿主としてカビタンスを利用する.
- 生物学的触媒を模倣して テンプレート反応で見られる 従来の宿主-ゲストの関係を逆転させる
主な方法:
- 長鎖α,ω-二アルデヒドのアルドール/脱水反応を促進するために,キャビタンスを適用する.
- 二酸化アルデヒドを折りたたまれた形状に導くために,空洞の内部で水害力を利用する.
- 分子間副作用よりもマクロサイクリングを促進するために水溶液で反応を行う.
主要な成果:
- 選択的な分子内アルドール/脱水反応は,キャビタンを使用して達成された.
- マクロサイクル製品は,30%から85%までの良い収穫量で得られました.
- この方法は11から17個の環の大きさのマクロサイクルを成功させた.
結論:
- カビタンドは,前体構成を制御することによって選択的なマクロサイクリングを促進する効果的な宿主として作用する.
- このカビタンド媒介的アプローチは,従来のマクロサイクリング方法に関連するエントロピック障壁を克服します.
- このシステムの逆の宿主-ゲストダイナミクスは,生物学的触媒にインスパイアされたテンプレート合成のための新しい戦略を提供します.
関連する概念動画
01:16Cycloaddition Reactions: MO Requirements for Thermal Activation
3.9K
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.
3.9K
02:11Conformations of Cyclohexane
14.4K
Cyclohexane does not exist in a planar form due to the high angle and torsional strain it would experience in the planar structure. Instead, it adopts non-planar chair and boat conformations.
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...
14.4K
01:16Cycloaddition Reactions: Overview
3.1K
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.
3.1K
02:30Stability of Substituted Cyclohexanes
14.1K
This lesson discusses the stability of substituted cyclohexanes with a focus on energies of various conformers and the effect of 1,3-diaxial interactions.
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
14.1K
01:34Woodward–Hoffmann Selection Rules and Microscopic Reversibility
3.5K
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...
3.5K
02:02Chair Conformation of Cyclohexane
17.1K
The chair conformation is the most stable form of cyclohexane due to the absence of angle and torsional strain. The absence of angle strain is a result of cyclohexane’s bond angle being very close to the ideal tetrahedral bond angle of 109.5° in its chair conformer. Similarly, the torsional strain is also absent owing to the perfectly staggered arrangement of bonds.
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this...
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this...
17.1K