リガンド制御コバルト触媒によるRegiodivergentアルキンの水酸化
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PubMedで要約を見る
まとめ
この要約は機械生成です。この研究は,地域分散アルキンの水酸化のためのコバルト触媒反応を導入する. リガンド選択は,単純な起始材料から多様なアルケンの同位体形成を制御する.
科学分野
- 有機化学
- キャタリシス
- 合成方法論
背景
- 単一のアルキンの前駆体からアルケンの同位体を生成するのは困難である.
- アルキンの機能化における地域選択性を制御することは,合成効率にとって極めて重要です.
研究 の 目的
- リガンド制御のコバルト触媒による地域分散アルキンの水酸化方法の開発.
- 同様のアルキンとアルキルハリド基板から異なるアルキン同位体の予測可能な合成を達成する.
主な方法
- 特定のビソクサゾリン (L1) とピリジン・オクサゾリン (L8) リガンドを用いたアルキンのコバルト触媒化水酸化.
- 末端および内部アルキンを様々な活性化および非活性化アルキルハリドで利用する.
主要な成果
- 高いステレオ選択性を持つ (E) -1,2-非置換および1,1-非置換アルケンを合成するための信頼性と予測可能なプロトコル.
- 内部アルキンから三置換アルケンの合成に成功した.
- 様々なアルキンとアルキルハリドを含む幅広い基板範囲で,優れた機能群耐性がある.
結論
- リガンド制御により,コバルト触媒によるアルキン水アルキル化において,地域差異的な結果が得られる.
- 開発された方法は,様々なアルケンの同位体に効率的にアクセスするための汎用的なプラットフォームを提供します.
関連する概念動画
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Thermodynamic Stability
Catalytic hydrogenation reactions help evaluate the relative thermodynamic stability of hydrocarbons. For example, the heat of hydrogenation of acetylene is −176 kJ/mol, and that of ethylene is −137 kJ/mol. The higher exothermicity...
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others.
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
Mechanism
The hydroboration-oxidation reaction is a two-step...
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...
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...