イリジウム触媒によるエナンチオセレクティブ・アリリックビニレーション
James Y Hamilton1, David Sarlah, Erick M Carreira
1Eidgenössische Technische Hochschule Zürich, HCI H335, 8093 Zürich, Switzerland.
Journal of the American Chemical Society
|December 22, 2012
まとめ
この研究は,ビニル三ボラートを使用した最初のイリジウム触媒非対称置換反応を導入します. この新しい方法は,高いエナチオセレクティブ性を持つ天然製品を含む,価値あるダイエンとトリエンを効率的に合成します.
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
- 合成有機化学 合成有機化学について
背景:
- ビニルトリフルオロボラート (Vinyl trifluoroborate) は,汎用性の高い合成反応剤である.
- 非対称な触媒は,エナティオメリカルに純粋な化合物を合成するために重要である.
- 1,4-ジーンとトリエンの合成のための効率的な方法の開発は重要です.
研究 の 目的:
- イリジウム触媒による最初の非対称的置換反応を,ビニルトリフルオロボラートで報告する.
- 1,4-ダイエンとトリエンのエナチオセレクティブ合成のための方法を開発する.
- 自然製品合成におけるこの方法の有用性を実証する.
主な方法:
- イリジウム- ((P,olefin) 複合体を触媒として利用する.
- カリウムアルケニルトリフルオロボラートと分岐した,ラセミアルリルアルコールを反応させる.
- 非対称な置換反応条件を用いる.
主要な成果:
- 置換反応で高い部位選択性を達成した.
- 最高99%の優れたエナチオセレクティブ性を得ました.
- (-) - ナイアソル, (-) - ヒノキレシノールを含む様々な1,4-ダイエン,トリエンを成功して合成した.
結論:
- 開発されたIr触媒反応は,ビニルトリフッ化ボラートによる同種の最初のものです.
- この方法は,エナチオメリックに濃縮されたダイエンとトリエンへの迅速なアクセスを提供します.
- この方法は,生物学的活性のある天然製品の合成に適用できます.
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関連する概念動画
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01:24[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement
The Claisen rearrangement is a [3,3] sigmatropic rearrangement of allyl vinyl ethers to unsaturated carbonyl compounds. The rearrangement is a concerted pericyclic reaction proceeding via a chair-like transition state.
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...
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.
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.
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...
02:24Reduction 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.