炭水化物触媒によるエナチオセレクティブアルケンの二酸化: 1,2-結合ディボロン複合体の反応性の強化
Lichao Fang1, Lu Yan1, Fredrik Haeffner1
1Department of Chemistry, Merkert Chemistry Center, Boston College , Chestnut Hill, Massachusetts 02467, United States.
Journal of the American Chemical Society
|February 9, 2016
まとめ
炭水化物由来の触媒は,有機合成の重要な反応であるエナチオセレクティブアルケンの二酸化を可能にします. 機理学的な研究では,1,2結合のディボロナートが中間物質として形成されていることが明らかである.
科学分野:
- 有機化学
- カタリシス
- 合成方法論
背景:
- アルケンの二酸化は,炭素-炭素および炭素-ボロン結合を作るための貴重な変換である.
- 効率的で選択的な触媒システムの開発は,引き続き活発な研究分野です.
- 炭水化物の分子は 持続可能で調節可能な 触媒設計のプラットフォームです
研究 の 目的:
- アルケンのエナチオセレクティブ・ディボレーションのための新しい触媒システムを開発する.
- 簡単に手に入る持続可能な炭水化物誘導体を活用する.
- 主要な中間物質の特定を含む反応メカニズムを明らかにする.
主な方法:
- 潜在的触媒として炭水化物由来化合物のスクリーニング
- エナンチオセレクティブ・ディボレーションの反応条件の最適化
- イソトープの標識と中間捕獲実験を含むメカニズム研究を行う.
主要な成果:
- 様々なアルケンの触媒的エナンチオセレクティブ・ディボレーションが成功しました.
- 炭水化物由来の触媒は高い効率と選択性を示した.
- 機械的調査は1,2-結合ディボロナートの中間作用の証拠を提供した.
結論:
- 容易に入手できる炭水化物由来の触媒は,エナチオセレクティブアルケンの二酸化に有効である.
- 開発された方法論は,価値あるオルガノボロン化合物を合成するための持続可能なアプローチを提供します.
- 1,2-結合ディボロナートを含むメカニズムの理解は,将来の触媒の開発を導くことができます.
関連する概念動画
02:36Regioselectivity and Stereochemistry of Hydroboration
9.7K
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.
9.7K
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
21.8K
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
21.8K
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
10.0K
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
10.0K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
4.0K
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...
4.0K
03:08Hydroboration-Oxidation of Alkenes
12.1K
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.
12.1K
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
18.3K
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...
18.3K