基因与CpCr(CO) 3H反应的机制. 对于激进循环化的应用
Deven P Estes1, Jack R Norton, Steffen Jockusch
1Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA.
Journal of the American Chemical Society
|August 21, 2012
概括
这项研究研究了CpCr(CO) ((3) H与活性的反应,揭示了原子转移 (HAT) 和单电子转移 (SET) 等化和循环反应中的独特机制.
科学领域:
- 有机金属化学 有机金属化学
- 反应机制 反应机制
- 催化剂是一种催化剂.
背景情况:
- CpCr ((CO) ((3) H 是一种已知的还原剂.
- 活性基因是有机合成中的多功能基质.
- 了解反应路径对于催化剂设计至关重要.
研究的目的:
- 阐明CpCr的反应机制{CO}{3H}与激活的基.
- 为了研究化的动力学和立体化学.
- 探索循环化反应的催化应用.
主要方法:
- 在中发生反应的动力学研究.
- 化产品的立体化学分析.
- 电子磁共振 (EPR) 光谱检测激素中间体.
- 催化化使用cobaloxime催化剂.
主要成果:
- 乙烯和乙烯化通过原子转移 (HAT) 机制进行.
- 甲基乙二碳酸盐 (DMAD) 反应涉及化和替代,可能通过单个电子转移 (SET) 途径.
- EPR光谱证实了在DMAD反应过程中形成的激素离子中间体.
- 在催化条件下,一种芳香的1,6 eneyne经过了循环处理,产生了78%的循环产品.
- 一种cobaloxime催化剂完全消除了化,产生了100%的循环产品.
结论:
- CpCr ((CO) ((3) H与激活的基具有多种反应性,包括HAT和SET机制.
- 催化系统可以选择性地促进循环化而不是化.
- 该研究提供了对有机金属反应途径和催化转换的见解.
相关概念视频
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.
Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
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.
Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.
Radical Reactivity: Nucleophilic Radicals
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 instance, consider...
Preparation of Alkynes: Dehydrohalogenation
Introduction
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.

![[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)