氧气激活由非黑米铁 (II) 复合物:α-基托碳酸盐与碳酸盐相比
Mark P Mehn1, Kiyoshi Fujisawa, Eric L Hegg
1Department of Chemistry and Center for Metals in Biocatalysis, 207 Pleasant Street Southeast, University of Minnesota, Minneapolis, MN 55455, USA.
Journal of the American Chemical Society
|June 26, 2003
概括
铁复合物与α-碳酸盐激活氧气,模仿非血铁氧酶. 这些模型经过基化和氧化脱碳化,揭示了α-基团在氧激活中的关键作用.
科学领域:
- 生物有机化学 生物有机化学
- 有机金属化学 有机金属化学
- 酵素仿真是一种很好的方法.
背景情况:
- 非海姆铁氧化酶是生物氧化反应中的关键酶.
- 了解它们的活跃部位需要合成模型.
- 硬质阻碍带,如Tp(Ph2),用于控制金属协调环境.
研究的目的:
- 合成和表征单核铁 (II) α-基托碳酸盐和碳酸盐复合物,作为非海姆铁氧化酶活性位点的模型.
- 研究这些模型复合体与二氧化碳的反应.
- 阐明氧气激活和基质基化机制.
主要方法:
- 合成铁 (II) 复合物与Tp (Ph2) 连接体和α-基托碳酸盐/碳酸盐连接体.
- 单晶X射线衍射用于结构确定.
- 谱学表征 (NMR,UV-Vis) 的方法.
- 用 (18) O 进行同位素标记研究.
- 动力学研究 (激活参数,哈梅特分析).
主要成果:
- 五坐标铁(II) 复合物与α-基托碳酸盐和碳酸盐配体的结构特征.
- 这两种类型的复合物都与O(2) 反应,以氧化Tp(Ph2) 配体,并经过氧化脱.
- 同位素研究证实了从O(2) 加入氧气到化联体和碳酸盐中.
- 动力学数据显示了对复合物和O2的第一级依赖,其中一个涉及铁) 超氧化物中间体的拟议机制.
- 阿尔法-基托碳酸盐复合物比碳酸盐复合物反应快得多.
结论:
- 合成的铁复合物有效地模拟非海姆铁氧化酶活性位点.
- 阿尔法-基因功能对于高效的氧激活和基化至关重要.
- 反应通过一种核性机制进行,包括超氧化物攻击和氧化脱化.
- 这些发现提供了对阿尔法基托酸依赖铁酶的催化机制的见解.
相关概念视频
Oxidation of Alcohols
In this lesson, the oxidation of alcohols is discussed in depth. The various reagents used for oxidation of primary and secondary alcohols are detailed, and their mechanism of action is provided.
The process of oxidation in a chemical reaction is observed in any of the three forms:
The process of oxidation in a chemical reaction is observed in any of the three forms:
Oxidations of Aldehydes and Ketones to Carboxylic Acids
Oxidation of aldehydes and ketones results in the formation of carboxylic acids. Aldehydes, bearing hydrogen next to the carbonyl group, are easily oxidized compared to ketones. This is because an aldehydic proton can easily be abstracted during oxidation.
Aldehydes readily undergo oxidation in strong oxidizing agents such as potassium permanganate and chromic acid. The oxidation can also be carried out using mild oxidizing agents such as silver oxide. In fact, aldehydes can be easily oxidized...
Aldehydes readily undergo oxidation in strong oxidizing agents such as potassium permanganate and chromic acid. The oxidation can also be carried out using mild oxidizing agents such as silver oxide. In fact, aldehydes can be easily oxidized...
Loss of Carboxy Group as CO2: Decarboxylation of β-Ketoacids
Carboxylic acids, upon heating, undergo a decarboxylation reaction by releasing carbon dioxide gas. Monocarboxylic acids do not undergo decarboxylation easily. However, a silver salt of carboxylic acid reacts with bromine or iodine under high temperature to release carbon dioxide gas and forms halide with one less carbon. This reaction is called the Hunsdiecker reaction.
Reactivity of Enolate Ions
Enolate ions are formed by the acid–base reaction of a carbonyl compound with a base. This leads to deprotonation of the α hydrogen atom, leading to a resonance-stabilized enolate ion where one of the contributing structures is an oxyanion, which imparts additional stability. Therefore, the proton on the α carbon is more acidic in nature than that of other sp3-hybridized C–H bonds but less acidic than those in O–H bonds where the negative charge in the conjugate base is localized on the oxygen...
Oxidation of Phenols to Quinones
In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
Enolate Mechanism Conventions
When a carbonyl compound is treated with a strong base, the α position gets deprotonated to give a resonance-stabilized intermediate called an enolate. Enolates are ambident nucleophiles because they possess two nucleophilic sites that can attack an electrophile owing to the delocalization of the negative charge between the α carbon and oxygen atoms. When the oxygen atom attacks an electrophile, it is called O-attack, whereas electrophilic attack via the α carbon is known as C-attack.
C-attack...
C-attack...
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