关于的实验和计算研究 (I) 催化区域选择性基化反应
Philip Andreetta1, Robert T Martin2, Charafa Souilah1
1Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35043, Marburg, Germany.
Angewandte Chemie (International ed. in English)
|September 29, 2023
概括
((I) 催化剂使三级碳酸盐的区域选择性基化能够与1,3-二碳化合物进行. 这种新方法显示出高产量和分支产品的选择性,即使存在二次碳酸.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 有机金属化学 有机金属化学
背景情况:
- 基化是一种关键的碳-碳键形成反应.
- 开发选择性催化剂,用于具有挑战性的基质,如三级基碳酸盐仍然是一个活跃的研究领域.
- 现有的催化方法往往缺乏选择性或需要特定的条件,如光催化.
研究的目的:
- 开发一种新的 ((I) 催化方法,用于三级碳酸盐的区域选择性基化.
- 探索精确定义的 (I) 复合体与双 (phosphine) 连接体的催化活性.
- 为了在基化反应中获得分支产品的高产量和区域选择性.
主要方法:
- 合成四面体 ((I) 复合体与双酸二 ((phosphine)) 连接体.
- 在基化反应中合成复合物的催化选.
- 使用各种三级和二级烯碳酸盐的反应选择性的研究.
- 涉及实验和计算方法的机械学研究.
主要成果:
- 确定[dppp) Co[PPh3) Cl]作为目标反应的有效催化剂.
- 实现了高产量和优秀的区域选择性,用于与各种三级基碳酸盐的分支产品.
- 对三级烯碳酸盐比二级碳酸盐具有显著的选择性.
- 基于机理学研究,提出了一种涉及Co (I) /Co (III) 中间体的催化循环.
结论:
- 开发了一种新的,高度区域选择性的 ((I) 催化方法,用于三级碳酸盐的基化.
- 该方法为分支产品提供了一种实用和选择性的方法,与光催化方法不同.
- 这些发现提供了对中介催化循环的有价值的见解,用于基替代.
相关概念视频
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
14.3K
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...
14.3K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
7.8K
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.
7.8K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.3K
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...
3.3K
02:36Regioselectivity and Stereochemistry of Hydroboration
8.2K
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
8.2K
02:13Reduction of Alkenes: Catalytic Hydrogenation
12.1K
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...
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...
12.1K
02:35Regioselectivity of Electrophilic Additions-Peroxide Effect
8.7K
In the presence of organic peroxides, the addition of hydrogen bromide to an alkene yields the isomer that is not predicted by Markovnikov’s rule. For example, the addition of hydrogen bromide to 2-methylpropene in the presence of peroxides gives 1-bromo-2-methylpropane. This addition reaction proceeds via a free radical mechanism, which reverses the regioselectivity. The free radical reaction mechanism involves three stages: initiation, propagation, and termination.
8.7K