C,N-サイクリックアゾメチンイミンとアルファ,ベータ不飽和アルデヒドの触媒エナチオセレクティブ1,3-二極サイクロアディション
Takuya Hashimoto1, Yuko Maeda, Masato Omote
1Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
Journal of the American Chemical Society
|March 5, 2010
まとめ
この研究では,エナチオセレクティブの1,3-二極サイクロアディション反応のためのC,N-サイクルアゾメチンイミンを導入しています. これらの反応は,テトラヒドロアイソキノリンやピペリジンなどの価値ある医薬品の構成要素を効率的に生成します.
科学分野:
- 有機化学 オーガニック・ケミストリー
- アシンメトリック・カタリシス
背景:
- アゾメチンイミンは,有機合成における多用途の二極体である.
- C,N-サイクリックアゾメチンイミンは,独特の反応性を持つ未知のサブクラスを表しています.
- 窒素を含むヘテロサイクルのエナチオセレクティブ合成は,薬物の発見に不可欠です.
研究 の 目的:
- 非対称な触媒におけるC,N-サイクルアゾメチンイミンの有用性を調査する.
- 高度にエナチオセレクティブの1,3-二極サイクロアディション反応を開発するために.
- 薬学的に重要なテトラヒドロアイソキノリンとピペリジンの支架にアクセスするには.
主な方法:
- 利用されたC,N-サイクルアゾメチンイミンは1,3-二極体として.
- チラルの触媒としてチタン-BINOLATE複合体を使用した.
- 1,3-二極サイクロアディションでエナルと反応した.
- クイラルクロマトグラフィーとスペクトロスコーピーを用いて製品のステレオ化学を分析した.
主要な成果:
- 高度にエナチオセレクティブの1,3-二極サイクロアディション反応を達成しました.
- C,N-サイクリックアゾメチンイミンの有効な応用が実証されました.
- 優れたステレオ制御でテトラヒドロアイソキノリンとピペリジンモチーフを生成します.
- この変換の効果的な触媒として,チタンビノ酸塩を特定しました.
結論:
- C,N-サイクルアゾメチンイミンは,非対称サイクロアディションのための貴重なシントンです.
- タイタニウムビノ酸塩触媒は,キラル窒素ヘテロサイクルへの効率的なアクセスを可能にします.
- この方法論は,重要な医薬品の中間製品への新しい経路を提供します.
関連する概念動画
Aldehydes and Ketones with Amines: Imine and Enamine Formation Overview
Primary amines react with carbonyl compounds—aldehydes and ketones—to generate imines. Imines consist of a C=N double bond and are named Schiff bases after its discoverer—the German chemist Hugo Schiff. On the other hand, secondary amines react with carbonyl compounds to give enamines. In enamines, the presence of a C=C double bond adjacent to the nitrogen atom leads to the delocalization of the lone pair.
Synthesis of α-Substituted Carbonyl Compounds: The Stork Enamine Reaction
α-Substituted ketones or aldehydes can be synthesized from enamines by the Stork enamine reaction, named after its pioneer Gilbert Stork. Enamines are useful synthetic intermediates where the lone pair on nitrogen is in conjugation with the C=C bond. They resemble enolate ions, as the resonance forms of both species have a nucleophilic α carbon.
Preparation of 1° Amines: Azide Synthesis
Direct alkylation of ammonia produces polyalkylated amines, along with a quaternary ammonium salt. To exclusively prepare primary amines, the azide synthesis method can be used.
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
Aldehydes and Ketones with Amines: Enamine Formation Mechanism
Enamine formation involves the addition of carbonyl compounds to a secondary amine through a series of reactions. The mechanism begins with the generation of carbinolamine, a nucleophilic attack followed by several proton transfer reactions. The hydroxyl group of the carbinolamine is converted into water to make a better leaving group that can push the reaction forward by eliminating a water molecule. In enamine formation, the last step involves the abstraction of a proton from the α carbon to...
Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Robinson annulation is a base-catalyzed reaction for the synthesis of 2-cyclohexenone derivatives from 1,3-dicarbonyl donors (such as cyclic diketones, β-ketoesters, or β-diketones) and α,β-unsaturated carbonyl acceptors. Named after Sir Robert Robinson, who discovered it, this reaction yields a six-membered ring with three new C–C bonds (two σ bonds and one π bond).
Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...


