ニトロサエレン-アルキンサイクル添加のメカニズムについて
Andrea Penoni1, Giovanni Palmisano, Yi-Lei Zhao
1Dipartimento di Scienze Chimiche ed Ambientali, Universita degli Studi dell'Insubria, Via Valleggio 11, 22100, Como, Italy.
Journal of the American Chemical Society
|December 20, 2008
まとめ
この研究では,ニトロサレンとアルキンが段階的なダイラジカルメカニズムで反応してN-ヒドロキシインドールを形成することを明らかにしました. 実験データと計算データにより,反応経路と代用物質が反応速度に与える影響が明らかになる.
科学分野:
- 有機化学 オーガニック・ケミストリー
- 反応メカニズム 反応メカニズム
- コンピューティング・ケミストリー
背景:
- ニトロサレンとアルキンは,有機合成の重要な構成要素である.
- これらの化合物の反応機構を理解することは,新しい合成方法論の開発に不可欠です.
研究 の 目的:
- ニトロサレンとアルキンの反応メカニズムを解明する.
- 反応速度と地域選択性に対する置換剤の影響を調査する.
- 実験的発見を計算研究で検証する.
主な方法:
- 置換されたニトロサレンとアルキンの間の反応の運動学的研究.
- 運動同位体効果の測定. 運動同位体効果の測定.
- 密度関数理論 (DFT) の計算は, (U) B3 LYP/6-31+G (d) レベルで行われている.
主要な成果:
- 反応は,N-C結合形成を伴う段階的なダイラジカルメカニズムを経由して進行し,続いてC-C結合形成が続く.
- ニトロサレンの電子取り除く群とアルキンの電子提供群が反応を加速する.
- 計算による研究は,地域選択性と置換効果を正確に予測します.
結論:
- 反応のメカニズムは,段階的なダイラジカルサイクル加法である.
- 置換効果は,反応速度を調節する上で重要な役割を果たします.
- 組み合わせた実験的および計算的アプローチは,反応の包括的な理解を提供します.
関連する概念動画
01:09Conjugate Addition to α,β-Unsaturated Carbonyl Compounds
α,β-Unsaturated carbonyl compounds are molecules bearing a carbonyl and alkene functionality in conjugation with each other. The conjugation in the molecule leads to three resonance structures. The hybrid form exhibits two probable electrophilic sites: the carbonyl carbon and the β carbon.
01:16Cycloaddition Reactions: Overview
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
02:27Preparation of Alkynes: Alkylation Reaction
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
01:18Nucleophilic Addition to the Carbonyl Group: General Mechanism
The carbonyl carbon in an aldehyde or ketone is the site of a nucleophilic attack due to its electron-deficient nature. Depending on the strength of the incoming nucleophile, the reaction occurs via different mechanistic pathways.
A stronger nucleophile can directly attack the electrophilic center, the carbonyl carbon. The HOMO orbital of the nucleophile interacts with the LUMO (π* antibonding) orbital present on the carbonyl carbon. This interaction breaks the π bond and shifts the π bonding...
A stronger nucleophile can directly attack the electrophilic center, the carbonyl carbon. The HOMO orbital of the nucleophile interacts with the LUMO (π* antibonding) orbital present on the carbonyl carbon. This interaction breaks the π bond and shifts the π bonding...
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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.
01:27Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Robinson annulation is a base-catalyzed reaction for the synthesis of 2-cyclohexenone derivatives from 1,3-dicarbonyl donors (such as cyclic diketones, β-ketoesters, or β-diketones) and α,β-unsaturated carbonyl acceptors. Named after Sir Robert Robinson, who discovered it, this reaction yields a six-membered ring with three new C–C bonds (two σ bonds and one π bond).