不安定アルキル基の光酵素生成:非対称的還元サイクル
Phillip D Clayman1, Todd K Hyster1
1Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
Journal of the American Chemical Society
|August 29, 2020
まとめ
研究者らは,フラビン還元酵素を用いた新しい光酵素法を開発し,エナチオセレクティブサイクリングのための不安定なラジカルを作成した. これは,複雑な反応におけるステレオ化学を正確に制御することを可能にすることで,過激な化学を進歩させます.
科学分野:
- 生物触媒と有機化学
- 酵素工学と光化学
背景:
- フラビン依存酵素は,通常,光照射で安定したラジカルを生成します.
- 酵素光触媒を用いた不安定化ラジカルの形成はこれまで報告されていません.
- 基質反応におけるステレオ選択性を制御することは,合成化学における重要な課題である.
研究 の 目的:
- フラビン依存酵素が不安定な核愛性ラジカルを生成する可能性を調査する.
- 光酵素触媒を用いたエナンチオセレクティブのラジカルサイクリング反応を開発する.
- 放射能生成とステレオ選択的水素原子移転のメカニズムを探求する.
主な方法:
- アルキルイオジドが不安定なラジカルを生成する前駆体として利用された.
- 酵素活性部位内のフラビン基板電荷伝達複合体の光刺激を用いる.
- フラビンセミキノンからサイクルラジカルの中間物質へのステレオ選択的水素原子移転を調査した.
主要な成果:
- 光酵素触媒を用いて,不安定な核性ラジカルを生成した.
- 多種多様な基板での急性循環反応で高いエナチオ選択性を達成した.
- 放射性物質の形成を促進する 複合的な電荷伝達機構の証拠を 提供した.
結論:
- 光酵素触媒は,不安定なラジカルを生成し,制御するために利用できます.
- このアプローチは 伝統的な化学の限界を克服し 新しい合成経路を提供しています
- 開発された方法は,過激な文献の主要な課題に取り組む,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.
関連する概念動画
01:10Radical Reactivity: Steric Effects
2.3K
The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic...
Along with electronic...
2.3K
01:11Radical Reactivity: Overview
2.5K
Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired...
2.5K
01:33Radical Reactivity: Intramolecular vs Intermolecular
2.1K
Radical reactions can occur either intermolecularly or intramolecularly. In an intermolecular radical reaction, a nucleophilic radical adds to an electrophilic alkene or vice versa. In such reactions, the radical and generally the alkene, which is also called the radical trap, are two different molecules. Additionally, for such intermolecular reactions to occur, the radical trap must be active, present in an excess concentration, and the radical starting material must have a weak...
2.1K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.7K
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...
3.7K
01:18Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism
2.5K
Birch reduction uses solvated electrons as reducing agents. The reaction converts benzene to 1,4-cyclohexadiene. The reaction proceeds by the transfer of a single electron to the ring to form a benzene radical anion. This anion is highly basic—it abstracts a proton from the alcohol to form a cyclohexadienyl radical. Another single electron transfer gives the cyclohexadienyl anion. A proton transfer from the alcohol forms 1,4-cyclohexadiene. Since this reduction occurs via radical anion...
2.5K
01:02Radical Reactivity: Electrophilic Radicals
2.3K
Radicals adjacent to electron‐withdrawing groups are called electrophilic radicals. These radicals readily react with nucleophilic alkenes. For example, the malonate radical, in which the radical center is flanked by two electron‐withdrawing groups, reacts readily with butyl vinyl ether, which consists of an electron‐donating oxygen substituent. The reaction between electrophilic malonate radical and nucleophilic vinyl ether is favored because the radical has a...
2.3K