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Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
Published on: November 9, 2019
オーガニック分子による陽子移転触媒によるブテノリドの非対称オレフィンイソメリゼーション
Yongwei Wu1, Ravi P Singh, Li Deng
1Department of Chemistry, Brandeis University, Waltham, Massachusetts 02454-9110, United States.
Journal of the American Chemical Society
|July 20, 2011
まとめ
研究者は,エナチオセレクティブオレフィンイソメリゼーションのための新しいキラル有機触媒を開発しました. このバイオミテック型陽子伝達触媒は,不飽和ブテノリドを高精度で有価なキラル製品に効率的に変換します.
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:
- オレフィンイソメリゼーションは,有機合成における重要な変換である.
- この反応のためのエナチオセレクティブ・メソッドの開発は,依然として大きな課題です.
- バイオミメティックアプローチは,効率的な触媒を設計するための有望な戦略を提供します.
研究 の 目的:
- エナチオセレクティブオレフィンイソメリゼーションのための新しいキラル有機触媒を開発する.
- この変換におけるバイオミメティック・プロトン伝搬触媒の応用を調査する.
- 開発された触媒システムの範囲と限界を探求する.
主な方法:
- 新しいキラル有機触媒の設計と合成.
- オレフィンイソメリゼーションのためのバイオミメティック・プロトン転送触媒.
- β,γ-不飽和ブテノリドをα,β-不飽和ブテノリドにエナンチオセレクティブ変換する.
- 反応経路を解明するためのメカニズム研究.
主要な成果:
- 前例のないエナチオセレクティブおよび一般的なオレフィンイソメリゼーションを達成しました.
- 多種多様な単体および非置換β,γ不飽和ブテノリドを変換した.
- 高いエナチオセレクティビティと収量で対応するキラルα,β不飽和ブテノリドが得られました.
- 触媒の負荷が0.5mol%以下で,高い触媒効率が実証されています.
- 機械学の研究では,速さ決定のステップとしてプロトネーションを特定しました.
結論:
- 開発されたキラル有機触媒は,バイオミメティックな陽子の移転を介して,高度にエナチオセレクティブで一般的なオレフィンイソメリゼーションを可能にします.
- この方法により,価値あるキラル α,β-不飽和ブテノリドに効率的にアクセスできます.
- この発見は,非対称合成における陽子転移触媒のメカニズムに関する新しい洞察を提供します.
関連する概念動画
03:08Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
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.
02:17Reduction 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...
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
01:13Olefin Metathesis Polymerization: Overview
Recently, the development of olefin metathesis polymerization advanced the field of polymer synthesis. Simply put, the reorganization of substituents on their double bonds between two olefins in the presence of a catalyst is known as the olefin metathesis reaction. The use of metathesis reaction for polymer synthesis is called olefin metathesis polymerization.
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
02:36Regioselectivity and Stereochemistry of Hydroboration
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.