![Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F51444.jpg&w=3840&q=50)
触媒的非対称ピクテ・スペングラー反応
Jayasree Seayad1, Abdul Majeed Seayad, Benjamin List
1Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany.
Journal of the American Chemical Society
|January 26, 2006
まとめ
キラルリン酸を用いた新しい触媒的非対称ピクテ・スペングラー反応が開発されました. この方法は,トリプタミンとアルデヒドから高収量とエナティオメール純度のテトラヒドロベータカルボリン誘導体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・シンセシス
- カタリシス カタリシス カタリシス
背景:
- ピクテ・スペングラー反応は,インドルアルカロイドを合成するための重要な方法である.
- 非対称的な変異を開発することは,エナティオメリカルに純粋な化合物にアクセスするために不可欠です.
研究 の 目的:
- 新しい触媒的非対称ピクテ・スペングラー反応を開発する.
- テトラヒドロベータカルボリンの合成において,高い収穫量とエナチオセレクティブ性を得るために.
主な方法:
- 置換トリプタミンとアルデヒドを基質として利用する.
- 触媒としてキラルリン酸の触媒量を使用します.
- 反応条件を優化して,収量とエナティオメア過剰を発生させる.
主要な成果:
- 様々なテトラヒドロベータカルボリン誘導体の合成に成功しました.
- 高い収穫量と優れたエナティオメール過量 (ee) を達成した.
- アリファティックアルデヒドとアロマティックアルデヒドの両方との反応の広範な適用性を実証しました.
結論:
- 開発された触媒非対称ピクテ・スペングラー反応は,非常に効率的な方法である.
- キラルリン酸触媒は,エナチオセレクティブ合成のための強力なツールを提供します.
- この方法論は,キラル型テトラヒドロベータカルボリン基板への貴重な経路を提供します.
関連する概念動画
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...
02:35Regioselectivity of Electrophilic Additions-Peroxide Effect
In the presence of organic peroxides, the addition of hydrogen bromide to an alkene yields the isomer that is not predicted by Markovnikov’s rule. For example, the addition of hydrogen bromide to 2-methylpropene in the presence of peroxides gives 1-bromo-2-methylpropane. This addition reaction proceeds via a free radical mechanism, which reverses the regioselectivity. The free radical reaction mechanism involves three stages: initiation, propagation, and termination.
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
01:34Woodward–Hoffmann Selection Rules and Microscopic Reversibility
Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...