アルキルおよびアリルハリドの活性化のためのハロゲン原子移転剤としてのアミノアルキル基

Timothée Constantin¹, Margherita Zanini¹, Alessio Regni¹

¹Department of Chemistry, University of Manchester, Manchester M13 9PL, UK.

Science (New York, N.Y.)

|February 29, 2020

まとめ

新しいα-アミノアルキルラジカルは有機ハリドを激素反応に活性化させ,危険な亜鉛反応剤により安全な代替品を提供します. この突破により温和な環境下では炭素と炭素の結合が効率的に形成されます

科学分野:

有機化学
ラジカル・ケミストリー
合成方法論

背景:

有機ハライドは汎用性の高い合成材料です
光還元化学におけるそれらの応用は,低還元ポテンシャルによって妨げられています.
タイン・ヒドリド還元などの伝統的な方法は危険な反応剤を含んでいます

研究の目的:

α-アミノアルキル基を用いた有機ハライドの活性化のための新しい方法を開発する.
既存の急性発射方法より安全で効率的な代替手段を提供するためです
この新しい戦略の有用性を様々な炭素-炭素結合形成反応で実証する.

主な方法:

単純なアミンからα-アミノアルキル基を生成する.
アルキルおよびアリルハライドにおける炭素-ハロゲン結合の均解活性化.
C-C結合形成のための酸化還元変異でこれらのラジカルを利用する.

主要な成果:

α-アミノアルキルラジカルは,古典的な亜鉛ラジカルのような反応性を示す.
アルキル・ハリドとアリル・ハリドの両方の活性化に成功
sp3-sp3,sp3-sp2 と sp2-sp2 の炭素結合の形成
軽度の反応条件下で達成された高い化学選択性.

結論:

α-アミノアルキル基は有機ハライドを活性化するための強力で安全なツールです.
この方法は,有機ハライドを含む急性反応の範囲を広げます.
この戦略は複雑な分子を作るための実践的なアプローチを提供します

さらに関連する動画

10:10

Application of Elemental Lanthanides in the Selective C-F Activation of Trifluoromethylated Benzofulvenes Providing Access to Various Difluoroalkenes

Published on: July 28, 2018

6.8K

09:45

A Protocol for Safe Lithiation Reactions Using Organolithium Reagents

Published on: November 12, 2016

31.9K

関連する概念動画

01:27

Radical Substitution: Halogenation of Alkanes and Alkyl Substituents

9.7K

In the presence of heat or light, alkanes react with molecular halogens to form alkyl halides by a substitution reaction called radical halogenation. This reaction has three steps: initiation, propagation, and termination, as seen in the radical chlorination of methane to produce methyl chloride.
In the initiation step of the reaction, the chlorine molecule undergoes homolytic cleavage in the presence of light or heat, forming two highly reactive chlorine radicals. Propagation occurs in two...

9.7K

01:31

Radical Substitution: Allylic Chlorination

3.0K

Typically, when alkenes react with halogens at low temperatures, an addition reaction occurs. However, upon increasing the temperature or under reaction conditions that form radicals, providing a low but steady concentration of halogen radicals, allylic substitution reaction is favored. This is because allylic hydrogens are very reactive as the formed intermediate is resonance stabilized. For example, when propene is treated with chlorine in the gas phase at 400 °C, it undergoes allylic...

3.0K

01:26

Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride

2.2K

Radical substitution reactions can be used to remove functional groups from molecules. The hydrogenolysis of alkyl halides is one such reaction, where the weak Sn–H bond in tributyltin hydride reacts with alkyl halides to form alkanes. Here, the reagent Bu3SnH yields tributyltin halide as a byproduct.
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...

2.2K

01:27

Radical Substitution: Allylic Bromination

6.3K

In organic synthesis, the formation of products can be altered by changing the reaction conditions. For example, a dibromo addition product is formed when propene is treated with bromine at room temperature. In contrast, propene undergoes allylic substitution in non-polar solvents at high temperatures to give 3-bromopropene. In order to avoid the addition reaction, the bromine concentration must be kept as low as possible throughout the reaction. This can be achieved using N-bromosuccinimide...

6.3K

01:02

Radical 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

01:16

Radical Reactivity: Nucleophilic Radicals

2.6K

Radicals adjacent to electron-donating groups are called nucleophilic radicals. These radicals readily react with electrophilic alkenes. The SOMO–LUMO interactions are the driving force for the reaction, where the high-energy SOMO of the electron-rich, nucleophilic radicals interacts with the low-energy LUMO of the electron-deficient, electrophilic alkenes. Such SOMO–LUMO interactions are the basis of reactive radical traps, affecting the selectivity in radical reactions. For...