非対称な触媒は,イリジウム複合体のイナーテッド・キラル・アット・メタルを用いて行われる
Liang-An Chen1, Weici Xu, Biao Huang
1Fujian Provincial Key Laboratory of Chemical Biology, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People's Republic of China.
Journal of the American Chemical Society
|May 16, 2013
まとめ
新しいイリジウム (III) 複合体は,ナイトロアルケンの非常に効率的な非対称的転送水素化を可能にします. この金属触媒は,非共性相互作用によって優れたエナチオセレクティブ性と低触媒負荷を達成し,多くの有機触媒の性能を上回ります.
科学分野:
- 有機金属化学 有機金属化学
- アシンメトリック・カタリシス
- オーガニック・シンセシス オーガニック・シンセシス
背景:
- チラルの触媒は,エナティオメリカルに純粋な化合物を合成するために不可欠です.
- 非対称的移転水素化は,有機合成における重要な変換である.
- 効率的で選択的な触媒の開発は,依然として大きな課題です.
研究 の 目的:
- 触媒的非対称的転送水素化のための新しいキラル-at-metalイリジウム (III) 複合体を開発する.
- 触媒のメカニズムを調査し,非共性相互作用に焦点を当てます.
- 効率性,エナチオセレクティブ性,および触媒負荷の観点から触媒の性能を評価する.
主な方法:
- キラル・アット・メタル・イリジウム (III) 複合体の合成と特徴付け.
- 複合体の適用は,β,β'-非置換のニトロアルケンの非対称的移転水素化における触媒として用いられる.
- エナティオメール過量 (ee) を決定する技術を用いた触媒産物の分析.
- 弱相互作用の役割を理解するための計算学または機械学的研究.
主要な成果:
- イリジウム (III) 複合体は,非対称的移転水素化の触媒として高い効率性を示した.
- 99% eeまでのエナティオメア過剰が達成されました.
- 触媒は,低触媒負荷 (0.1 mol %まで) でさえも優れた性能を示した.
- 触媒は,リガンド球内の弱い相互作用 (例えば,水素結合) を介して,直接の金属の調整なしに進行した.
結論:
- 構造的に頑丈な支架は,非共性触媒の利用に有利である.
- 開発されたイリジウム (III) 複合体は,非対称的移転水素化のための非常に効果的な触媒です.
- 形状的に制約された協力的相互作用は,触媒の高性能の鍵です.
関連する概念動画
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
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...
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...
01:22Heterogeneous Catalysis
Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with 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.
02:05Prochirality
The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...