一个基:它的设计,结构,功能和反应机制
Hiroshi Naka1, Masanobu Uchiyama, Yotaro Matsumoto
1Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai 980-8578, Japan. naka@mail.pharm.tohoku.ac.jp
Journal of the American Chemical Society
|February 1, 2007
概括
一种新的酸基可使芳香化合物的区域选择性功能化. 这种强大的工具可以合成复杂的芳香结构,并且在阿里法化学中显示出创造功能化分子的前景.
科学领域:
- 有机金属化学 有机金属化学
- 合成有机化学 合成有机化学
背景情况:
- 芳香化合物的直接功能化对于合成复杂分子至关重要.
- 现有的方法往往缺乏区域选择性或需要恶劣的条件.
研究的目的:
- 设计和开发一种新的基,用于区域选择性和化学选择性直接生成功能化的芳香化合物.
- 为了探索这种试剂在芳香和酸化学中的实用性.
- 阐明基的机制和结构特征.
主要方法:
- 酸基的合成和表征,i-Bu(3) Al(TMP) Li.
- 电友性捕获反应 (例如,与I(2),Cu/Pd催化C-C键的形成,氧化).
- 谱学研究 (NMR,现场FT-IR) 和X射线晶体学.
- 密度函数理论 (DFT) 的计算.
主要成果:
- 酸基,i-Bu(3) Al(TMP) Li,有效地产生具有高区域和化学选择性的功能化芳香化合物.
- 在制备1,2-和1,2,3-多替代芳香化合物的过程中被证明是有用的.
- 在阿里法化学中成功应用,用于将功能化的基乙烯和碳酸盐添加到化物中.
- 结构分析显示了一种Li/Al双金属复合体,其中作为识别部位.
- 机理学研究表明,TMP配体容易形成 adduct 和deprotonation,区域选择性是由协调效应驱动的.
结论:
- 开发的酸基是一种强大的工具,用于选择性芳香和酸功能化.
- /双金属结构和协调效应是观察到的反应性和选择性的关键.
- 这种方法为复杂的多替代有机分子提供了一条多功能途径.
相关概念视频
Acid Halides to Alcohols: LiAlH4 Reduction
Acid halides are reduced to alcohols in the presence of a strong reducing agent like lithium aluminum hydride.
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
Base-Catalyzed Aldol Addition Reaction
As depicted in Figure 1, base-catalyzed aldol addition involves adding two carbonyl compounds in aqueous sodium hydroxide to form a β-hydroxy carbonyl compound.
Amides to Amines: LiAlH4 Reduction
Amide reduction with strong reducing agents like lithium aluminum hydride proceeds through a nucleophilic acyl substitution to form amines. Primary, secondary, and tertiary amides yield primary, secondary, and tertiary amines, respectively.
Amide reduction requires two equivalents of the reducing agent, acting as a source of hydride ions. As shown in the figure, the reaction is initiated with a nucleophilic attack by the hydride ion at the carbonyl carbon to form a tetrahedral intermediate.
Amide reduction requires two equivalents of the reducing agent, acting as a source of hydride ions. As shown in the figure, the reaction is initiated with a nucleophilic attack by the hydride ion at the carbonyl carbon to form a tetrahedral intermediate.
Properties of Organometallic Compounds
Organometallic compounds are compounds that contain a carbon–metal bond. Carbon belongs to an organyl group like alkyl, aryl, allyl, or benzyl groups. The metal can be from Group I or Group II of the periodic table, a transition metal, or a semimetal.
Aldehydes and Ketones with Amines: Imine Formation Mechanism
Imine formation involves the addition of carbonyl compounds to a primary amine. It begins with the generation of carbinolamine through a series of steps involving an initial nucleophilic attack and then several proton transfer reactions. The second part includes the elimination of water, as a leaving group, to give the imine.
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
Aldehydes and Ketones with Amines: Imine and Enamine Formation Overview
Primary amines react with carbonyl compounds—aldehydes and ketones—to generate imines. Imines consist of a C=N double bond and are named Schiff bases after its discoverer—the German chemist Hugo Schiff. On the other hand, secondary amines react with carbonyl compounds to give enamines. In enamines, the presence of a C=C double bond adjacent to the nitrogen atom leads to the delocalization of the lone pair.

