内部アルキンの分子間水溶解におけるリガンド制御による顕著な地域およびステレオ多様性:実験的および理論的研究
Shengtao Ding1, Li-Juan Song, Lung Wa Chung
1Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong SAR, China.
Journal of the American Chemical Society
|August 27, 2013
まとめ
ルテニウム触媒は,リガンド制御によるアルキンの水酸化を可能にし,多様なビニルジサイランを生成します. ステリック・バルクとカタリスト・リガンドは,この効率的な合成方法において,逆の領域とステレオ選択性を決定する.
科学分野:
- 有機金属化学 有機金属化学
- カタリシス カタリシス カタリシス
- 合成有機化学 合成有機化学について
背景:
- 内部アルキンの分子間水酸化は,重要な合成変換である.
- これらの反応において高い地域性およびステレオ選択性を達成することは,依然として課題です.
- リンガンドの設計は,触媒的結果を制御する鍵です.
研究 の 目的:
- 内部アルキンの最初の高効率のリガンド制御された地域およびステレオダイバーゲントの分子間水酸化を明らかにすること.
- カチオニウムルテニウム複合体の,特に[Cp*Ru(MeCN) 3+と[CpRu(MeCN) 3+の触媒活性を調査する.
- 選択性を制御するシリル群と触媒リガンドの役割を調査する.
主な方法:
- カチオン型ルテニウム複合体 ([Cp*Ru(MeCN) 3+と[CpRu(MeCN) 3+) を用いた触媒.
- シリルアルキンの分子間水酸化.
- 反応機構を解明するための密度関数理論 (DFT) 計算.
- 理論的な予測の実験的検証.
主要な成果:
- 内部アルキンのリガンド制御,レジオおよびステレオダイバージェントの分子間水酸化の発見.
- ルテニウム触媒リガンド (Cp*対Cp) に応じて,優れた,逆の地域とステレオ選択性 (α反対βシン添加) を有するビニルジサイランの形成.
- シリルマスク群が選択性のためのステリックバルクを提供し,汎用的な製品派生を可能にすることを実証.
- DFTの計算により,酸化性水金属化,イソメリ化,還元性シリル移動を含むメカニズムが明らかになった.
結論:
- リガンドとアルキン置換物のステリック効果は,地域とステレオ選択性を決定的に支配する.
- アルキンのシリル基とルテニウム触媒リガンドの相互作用が観測されたステレオダイバージェンスを決定する.
- この作品は,制御された水溶化によって貴重な構成要素を合成するための多用途のプラットフォームを提供します.
関連する概念動画
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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.
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.
02:40Alkynes to Aldehydes and Ketones: Acid-Catalyzed Hydration
Introduction
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
02:36Regioselectivity and Stereochemistry of Hydroboration
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 stereochemistry.
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 stereochemistry.
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
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.
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.
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
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...
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...