立体选择性分子间合物C-H三酸氧化功能化的基
Rauful Alam1, Lukasz T Pilarski, Elias Pershagen
1Department of Organic Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
Journal of the American Chemical Society
|May 17, 2012
概括
这项研究引入了一种用催化方法,用于使用新型氧化剂对基的三酸氧化. 该反应显示了循环基因的高区域和二聚体选择性,提供了一个新的合成途径.
科学领域:
- 有机化学 有机化学
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
背景情况:
- 基C-H功能化是有机合成中的关键转化.
- 的催化提供了C-H激活和功能化的多功能途径.
- 开发选择性方法,在基位置引入氧化功能仍然是一个活跃的研究领域.
研究的目的:
- 开发一种新的催化方法,用于替代基的直接C-H三酸氧化.
- 在循环基上研究这种转变的区域和二聚体选择性.
- 阐明反应机制,包括中间体的作用.
主要方法:
- 用Palladium催化反应使用PhI(OCOCF3) 2作为氧化剂和乙氧化源.
- 用各种替代的基质范围探索,重点是单替代环烯和环烯.
- 机理研究涉及潜在的 (η3-基) Pd (II) 中间体的表征和反应性.
主要成果:
- 取得了成功的Pd-催化基C-H三乙氧化替代基的实现.
- 对于单位替代环烯和环烯的三酸氧化,观察到出色的区域和异位选择性.
- 机理学研究表明,涉及到刻板选择性Pd(IV) 中间体和随后的还原性淘汰.
结论:
- 已经建立了一个新的,高效的方法,用于化催化化C-H三酸氧化.
- 该反应提供了一条高度选择性的路径,用于三酸氧化循环基.
- 涉及Pd(IV) 中间体的拟议机制为反应的立体化学控制提供了洞察力.
相关概念视频
Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others.
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
Acid-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...
Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Preparation 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.
Electrophilic Aromatic Substitution: Friedel–Crafts Acylation of Benzene
The Friedel–Crafts acylation reactions involve the addition of an acyl group to an aromatic ring. These reactions proceed via electrophilic aromatic substitution by employing an acyl chloride and a Lewis acid catalyst such as aluminum chloride to form aryl ketone.
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.


