Li+誘発のシグマ結合メタテシス:メチル交換のためのアリル,メチル交換は,メチル化されたモノカルバドデカボラートアニオン中のボロンで行われる
Zbynĕk Janousek1, Uwe Lehmann, Jakub Castulík
1Department of Chemistry and Biochemistry, University of Colorado at Boulder, Colorado, USA.
Journal of the American Chemical Society
|April 1, 2004
まとめ
190°Cのリチウムカルボラート誘導体とアリルシランとの間に新しいシグマ結合転移反応が観察されました. この反応にはアクティブなリチウムカチオンが必要で,アリラートカルボレートアニオンを生成し,その構造はX線結晶学で解明される.
科学分野:
- 有機金属化学 有機金属化学
- ボロン化学 ボロン化学
- カーボラン化学
背景:
- カーボランは,ユニークな電子的および構造的性質を持つ多用途のボロン・クラスター化合物です.
- シグマ結合メタテシスは,新しい炭素元素結合を形成するための強力なツールです.
- カーボラン誘導体の反応性を理解することは,新しい合成方法論の開発に不可欠です.
研究 の 目的:
- リチウムモノカルバドデコボラート誘導体のシグマ結合メタテシス反応性を調査する.
- メタテシス反応に対する対カチオンの影響を調査する.
- アリレーション反応の産物を特徴付けるために.
主な方法:
- リチウムモノカルバドデカボレート誘導体 (1a) とp-ブロモフェニルトリメチルシランの高温反応.
- アリラート炭酸塩アニオン (2) の構造決定のためのX線結晶学.
- セシウム塩 (1b) と12-クラウン-4の添加を用いた比較研究
主要な成果:
- 正式なシグマ結合の転移は190°Cで発生し,テトラメチルシランとアリレイテッドカルボレートアニオンを生成した.
- 反応は活性Li+カチオンの存在に依存しており,セシウム塩または冠エーテルの存在で失敗した.
- アリレートカルボラートアニオンのX線構造が成功裏に決定されました.
結論:
- リチウムモノカルバドデコバレート誘導体は,アリルシラネスとのシグマ結合メタテシスを受けることができます.
- この特定のメタテシス反応には,活性Li+カチオンの存在が不可欠である.
- この研究は,メタテシスによるカルボラン機能化のメカニズムと範囲についての洞察を提供します.
関連する概念動画
Voltaic/Galvanic Cells
Spontaneous Chemical Reactions
Spontaneous redox reactions occur abundantly in nature. The chemical reaction occurring in a disposable AA battery powering our remote controls is one such example of a spontaneous redox reaction. Another example is the immersion of coiled copper wire into an aqueous silver nitrate solution. The reaction shows a gradual, visually impressive color change from colorless to bright blue and the formation of a grey precipitate on the copper wire. In this experiment,...
Spontaneous redox reactions occur abundantly in nature. The chemical reaction occurring in a disposable AA battery powering our remote controls is one such example of a spontaneous redox reaction. Another example is the immersion of coiled copper wire into an aqueous silver nitrate solution. The reaction shows a gradual, visually impressive color change from colorless to bright blue and the formation of a grey precipitate on the copper wire. In this experiment,...
Cooperative Allosteric Transitions
Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand binds to any of these subunits, it triggers a conformational change that affects the binding sites in the other subunits; this can change the affinity of the other sites for their respective ligands. The ability of the protein to change the shape of its binding site is attributed to the presence of a mix of flexible and stable segments in the...
Cooperative Allosteric Transitions
Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand binds to any of these subunits, it triggers a conformational change that affects the binding sites in the other subunits; this can change the affinity of the other sites for their respective ligands. The ability of the protein to change the shape of its binding site is attributed to the presence of a mix of flexible and stable segments in the...
Nitriles to Ketones: Grignard Reaction
Organomagnesium halides, commonly known as Grignard reagents, convert nitriles to ketones and proceed through a nucleophilic acyl substitution. Nitriles react with a Grignard reagent, followed by an aqueous acid, to yield ketones. The reaction introduces a new carbon–carbon bond. The alkyl–magnesium bond in the Grignard reagent is highly polar, so the alkyl carbon develops a carbanionic character and acts as a nucleophile.
The mechanism begins with a nucleophilic attack by the Grignard reagent...
The mechanism begins with a nucleophilic attack by the Grignard reagent...
Cooperative Allosteric Transitions
Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand binds to any of these subunits, it triggers a conformational change that affects the binding sites in the other subunits; this can change the affinity of the other sites for their respective ligands. The ability of the protein to change the shape of its binding site is attributed to the presence of a mix of flexible and stable segments in the...
Transition State Theory
Transition-state theory, also known as activated-complex theory, provides a molecular-level explanation of reaction rates in both gas-phase and solution-phase reactions. It extends earlier kinetic models by considering the formation of a short-lived, high-energy configuration during a reaction.The progress of a chemical reaction can be represented using a reaction profile, which plots potential energy against the reaction coordinate. As two reactant molecules approach one another, their...


