協調アルケーンに対するアミン攻撃:反マルコヴニコフからマルコヴニコフ製品への相互変換
Ruslan Pryadun1, Dinesh Sukumaran, Robert Bogadi
1Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, USA.
Journal of the American Chemical Society
|September 30, 2004
まとめ
プラチナアルケンの複合体は,ダイエチラミンと反応する. 小さいアルケンは核好性の攻撃を受け,マルコヴニコフ対産物 (anti-Markovnikoff products) を形成し,マルコヴニコフ産物 (Markovnikoff products) に変換する一方,大きなアルケンはアミンによって置き換えられる.
科学分野:
- 有機金属化学 有機金属化学
- 協調化化学について
- プラチナ・カタリシス
背景:
- アルケネリガンドを含むプラチナ複合体は,触媒作用において重要である.
- これらの複合体の核性分子との反応性を理解することは,合成アプリケーションにとって極めて重要です.
研究 の 目的:
- プラチナアルケンの一連の複合体を合成し,特徴づけること.
- これらの複合体のダイエチラミンとの反応を調査する.
- 調整アルケーンにダイエチラミン添加のメカニズムと地域選択性を解明する.
主な方法:
- 様々なアルケンのためのプラチナアルケンの複合体 PtCl ((2) (((PPh ((3)) (((アルケンの合成.
- NMRスペクトロスコピーとX線結晶学を用いた特徴化.
- 核愛性の攻撃と置換を研究するために,ダイエチラミンとの複合体の反応.
主要な成果:
- 一連のプラチナアルケンの複合体を成功裏に準備し,特徴づけました.
- ディエチラミンはアルケンを1 - ヘクセン,1 - オクテン,および1 - デクセンとの複合体で置き換えた.
- より小さな協調アルケーン (プロペン,1-ブーテン) に対するダイエチアミンによる核好性攻撃が発生し,当初は抗マルコヴニコフ製品が生じた.
- アンチ・マルコヴニコフ・アドクトは,アミン解離なしに室温でマルコヴニコフ・プロダクトにイソメリ化します.
結論:
- ディエチラミンとプラチナアルケンの複合体の反応性は,アルケンのサイズに依存しています.
- ニュクレオフィルの攻撃とそれに続くイソメリゼーションを含むメカニズム的経路は,より小さなアルケンのために提案されました.
- これらの発見は,核好性添加反応におけるオーガノプラチナ化合物の行動に関する洞察を提供します.
関連する概念動画
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...
01:21Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
00:51Base-Promoted α-Halogenation of Aldehydes and Ketones
α-Halogenation of aldehydes and ketones is a reaction involving the substitution of α hydrogens with halogens in the presence of a base. The reaction begins with the abstraction of α hydrogen by the base to produce a nucleophilic enolate ion. This intermediate undergoes a subsequent nucleophilic substitution with the halogen to produce a monohalogenated carbonyl compound. If the starting substrate has more than one α hydrogen, it is difficult to stop the reaction at the stage of...
01:16Amines to Alkenes: Hofmann Elimination
Alkenes can be obtained from amines via an E2 elimination. The amine is first converted into a good leaving group, such as a quaternary ammonium salt. This is accomplished by treating the amine with an excess of alkyl halide, which results in a halide salt. Next, the halide salt is transformed into a hydroxide salt that functions as a base to enable elimination.
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...
01:14Amines to Alkenes: Cope Elimination
Cope elimination reaction involves the conversion of tertiary amines to alkene using hydrogen peroxide under thermal conditions, as depicted in figure 1.
01:17Reactions of α-Halocarbonyl Compounds: Nucleophilic Substitution
Nucleophilic substitution in α-halocarbonyl compounds can be achieved via an SN2 pathway. The reaction in α-haloketones is generally carried out with less basic nucleophiles. The use of strong basic nucleophiles leads to the generation of α-haloenolate ions, which often participate in other side reactions.