エナチオセレクティブの有機触媒性アミン結合体添加
Young K Chen1, Masanori Yoshida, David W C MacMillan
1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Journal of the American Chemical Society
|July 20, 2006
まとめ
この研究は,最初のエナチオセレクティブの有機触媒性アミン結合添加を導入します. この新しい方法は,イミニウム触媒を用いて有価なβ-アミノアルデヒド中間物質を効率的に合成します.
科学分野:
- 有機化学 オーガニック・ケミストリー
- カタリシス カタリシス カタリシス
- アシンメトリック・シンセシス
背景:
- C-N結合形成のためのエナチオセレクティブ・メソッドの開発は,有機合成において極めて重要です.
- オーガノカタリシスは,複雑な分子構造のための金属のない代替手段を提供します.
研究 の 目的:
- 最初のエナチオセレクティブの有機触媒性アミン結合添加反応を開発する.
- 価値あるキラルベータアミノアルデヒド中間物質の合成を可能にします.
主な方法:
- LUMOを低下させるイミニウム触媒を用いた.
- 合理的に設計されたN-シリロキシカルバマート核フィール (HOMOで育てられた) を採用した.
- イミダゾリジノン2*pTSAを有機触媒としてスクリーニングした.
主要な成果:
- アルファ,ベータ不飽和アルデヒドに高度な化学およびエナチオセレクティブの1,4-添加を達成しました.
- 様々なN-保護のシルイロキシカルバメトの添加を成功的に触媒化しました.
- 合成的に有用なベータアミノアルデヒド中間物質を生成する.
結論:
- 開発されたプロトコルは,エナチオセレクティブアミン結合体添加における重要な進歩を表しています.
- 酵素濃縮ベータアミノ酸と1,3-アミノアルコールの迅速な合成により,合成的有用性を実証した.
関連する概念動画
Catalysis
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
Nucleophilic Addition to the Carbonyl Group: General Mechanism
The carbonyl carbon in an aldehyde or ketone is the site of a nucleophilic attack due to its electron-deficient nature. Depending on the strength of the incoming nucleophile, the reaction occurs via different mechanistic pathways.
A stronger nucleophile can directly attack the electrophilic center, the carbonyl carbon. The HOMO orbital of the nucleophile interacts with the LUMO (π* antibonding) orbital present on the carbonyl carbon. This interaction breaks the π bond and shifts the π bonding...
A stronger nucleophile can directly attack the electrophilic center, the carbonyl carbon. The HOMO orbital of the nucleophile interacts with the LUMO (π* antibonding) orbital present on the carbonyl carbon. This interaction breaks the π bond and shifts the π bonding...
Conjugate Addition to α,β-Unsaturated Carbonyl Compounds
α,β-Unsaturated carbonyl compounds are molecules bearing a carbonyl and alkene functionality in conjugation with each other. The conjugation in the molecule leads to three resonance structures. The hybrid form exhibits two probable electrophilic sites: the carbonyl carbon and the β carbon.
Conjugate Addition (1,4-Addition) vs Direct Addition (1,2-Addition)
α,β-Unsaturated carbonyl compounds with two electrophilic sites, the carbonyl carbon, and the β carbon, are susceptible to nucleophilic attack via two modes: conjugate or 1,4-addition and direct or 1,2-addition.
Conjugate addition results in a thermodynamically stable product. The reaction retains the stronger C=O bond at the expense of the weaker C=C π bond. The process is slow as the β carbon is less electrophilic than the carbonyl carbon.
Direct addition products are formed faster owing to...
Conjugate addition results in a thermodynamically stable product. The reaction retains the stronger C=O bond at the expense of the weaker C=C π bond. The process is slow as the β carbon is less electrophilic than the carbonyl carbon.
Direct addition products are formed faster owing to...
Catalysis
Catalysis influences the rate of chemical reactions by providing an alternative reaction pathway with lower activation energy. A catalyst speeds up a reaction, but it is not consumed during the process. The fundamental principle of catalysis is the ability of a catalyst to alter the reaction mechanism, often introducing a more efficient pathway than the uncatalyzed process.In a catalyzed reaction, the catalyst participates directly in the reaction mechanism. It interacts with reactants to form...
Heterogeneous 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...


