从化的基化C-H化的分子内化化
Sophie Rousseaux1, Michaël Davi, Julien Sofack-Kreutzer
1Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada. srous100@uottawa.ca
Journal of the American Chemical Society
|August 5, 2010
概括
这项研究引入了高效的催化分子内C(sp(3)) -H arylation使用化,产生各种循环化合物. 对连接体和条件的优化可以选择性合成有价值的循环氨酸,内氨酸等.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 合成方法论 合成方法论
背景情况:
- 催化C-H激活是有机合成中的一个强大的工具.
- 内部分子C ((sp ((3)) -H化提供了循环结构的直接途径.
- 以前的方法往往受到基质范围或反应条件的限制.
研究的目的:
- 开发有效的和一般的催化分子内C ((sp ((3)) -H化 (异) 化物.
- 通过使用易于获得的化和异化来扩大C(sp(3)) -H化范围.
- 为了实现各种有价值的循环化合物的高产量和选择性.
主要方法:
- 对联体 (P(t) Bu(3),PCyp(3),PCy(3) 和基/溶剂组合 (K(2) CO(3) /DMF,Cs(2) CO(3) /皮瓦力酸/梅西) 的选.
- 优化反应条件以获取不同的产品类别.
- 计算研究 (DFT(B3PW91)) 以阐明反应机制和选择性.
主要成果:
- 第一个有效的和一般的催化分子内C ((sp ((3)) -H化 (异) 化的例子.
- 成功合成了循环丁烯,英达烯,英多林,二二芬烯和英达.
- 对于初级C-H债券而不是二级/三级债券,证明了区域选择性,有利于五个成员的环形形成.
- 报告了40多个成功的C-H化示例.
结论:
- 开发的方法提供了一个通用的途径,从化中获得有价值的循环化合物.
- 连接物和基/溶剂的选择对于控制产品的结果和产量至关重要.
- 计算分析证实了C-H激活是决定速率的,并突出了C-H毒性相互作用在区域选择性中的作用.
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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 Addition to Alkynes: Hydrohalogenation
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.
Reduction of Alkenes: Catalytic Hydrogenation
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
Halogenation of Alkenes
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
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...


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