通过三元复合机制进行类似酶的催化:基桥式二核复合物通过N-化介导化学选择性O-化
Yukiko Hayashi1, Stefano Santoro, Yuki Azuma
1Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
Journal of the American Chemical Society
|April 16, 2013
概括
(II) 乙酸盐有效催化基组选择性化,性能优于其他过渡金属. 一个带有双二连接体的碳酸盐集群通过迈凯利斯-门机制实现了选择性转.
科学领域:
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
- 有机合成 有机合成
背景情况:
- 分子的选择性功能化在有机合成中至关重要.
- 过渡金属催化剂为化学转换提供了多功能反应能力.
- 区分类似的功能组,如基和氨基,是一个合成的挑战.
研究的目的:
- 开发一种催化系统,用于基组选择性化在氨基的存在下.
- 为了研究第一排晚过渡金属酸盐的催化活性.
- 为了阐明催化转化的机制.
主要方法:
- 过渡金属酸盐 (Mn,Fe,Co,Cu,Zn) 的选,用于乙化反应.
- 使用八核碳酸盐集群与含有的配体 (例如,2,2'-双).
- 一个关键的双核中间体的分离和表征.
- 动力学研究和密度函数理论 (DFT) 计算以确定反应机制.
主要成果:
- (II) 乙酸盐在氧基化过程中表现出更高的反应性和选择性.
- 基于碳酸盐集群和双二烯的高效催化系统被开发用于转化.
- 作为一个关键的中间体,分离了一种双核复合物,Co2 ((OCO ((t) Bu) 2 ((bpy) 2 ((μ2-OCH2-C6H4-4-CH3) 2 .
- 动力学和DFT研究表明了迈凯利斯-门行为和有序的三元复杂机制.
结论:
- 乙酸是一种有效的催化剂,可以在胺基上选择性化基.
- 碳酸盐集群与双二连接体相结合,形成高效的转化催化剂.
- 催化机制类似于双核金属酶的催化机制,涉及氧化物形成和协调.
相关概念视频
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
01:27Aldol Condensation with β-Diesters: Knoevenagel Condensation
The Knoevenagel condensation is an aldol-type reaction involving the condensation of aldehydes or ketones with active methylene compounds such as β-diesters to produce substituted olefins.
03:08Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
02:17Reduction 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...
03:00Preparation of Epoxides
Overview
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...