双重非対称的誘導によるアレンのエナチオ表面選択パラジウム誘導シリボレーション
Michinori Suginome1, Toshimichi Ohmura, Yoshihiro Miyake
1Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, and PRESTO, Japan Science and Technology Corporation (JST), Katsura, Nishikyo-ku, Kyoto 615-8510, Japan. suginome@sbchem.kyoto-u.ac.jp
Journal of the American Chemical Society
|October 14, 2005
まとめ
研究者らは,パラジウム触媒とキラル補助物を用いて,エンアンチオイン濃縮のβ-ボリヤルリルシランを合成した. この方法は,高いステレオ選択性を達成し,キラルオルガノシリコン化合物の新しい経路を提供しました.
科学分野:
- 有機金属化学 有機金属化学
- 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:
- チラルの有機シリコン化合物は,有機合成における貴重な構成要素である.
- ステレオ選択的合成のための効率的な方法の開発は,依然として課題です.
研究 の 目的:
- エナンチオ濃縮β-ボリヤルリルシランを合成するための新しいパラジウム触媒方法の開発.
- 非対称的なシリコン-ボロン結合加減反応におけるキラル補助物質の使用を調査する.
主な方法:
- パラジウムで触媒化されたエナチオ表面 - 端末アレンにシリコン-ボロン結合の選択的添加.
- パラジウム触媒を用いて,キラルモノデンテートフォスフィンリガンドを用いた.
- ボロン原子にキラル補助物質を搭載したシリルボランを使用した.
主要な成果:
- 抗酸化物質を濃縮したβ-ボリヤルリルシランを成功して合成した.
- 高い対面選択性を達成し,最大96%の解消率を達成しました.
- 立体化学を制御するキラル補助体の有効性を実証した.
結論:
- 開発されたパラジウム触媒反応は,キラルベータ-ボリヤルリルシランへの効率的な経路を提供します.
- 高いステレオ選択性を達成するために,キラル補助器の使用は極めて重要です.
- この方法論は,有機シリコン化合物の非対称合成のためのツールキットを拡張します.
さらに関連する動画
関連する概念動画
02:24Introduction to Electrophilic Addition Reactions of Alkenes
The double bond in a simple, unconjugated alkene is a region of high electron density that can act as a weak base or a nucleophile. The filled π orbital (HOMO) of the double bond can interact with the empty LUMO of an electrophile. A bonding interaction occurs when the electrophile attacks between the two carbons; the electrophile then accepts a pair of electrons from the π bond and undergoes addition across the double bond, yielding a single product.
Addition and elimination reactions can be...
Addition and elimination reactions can be...
02:46Halogenation of Alkenes
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
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.
02:34Preparation of Alkynes: Dehydrohalogenation
Introduction
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.