基基的直接催化不对称的阿尔多尔反应:不对称的Zn催化与Et(2)Zn/链接-BINOL复合体
Naoya Kumagai1, Shigeki Matsunaga, Tomofumi Kinoshita
1Contribution from the Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Journal of the American Chemical Society
|February 20, 2003
概括
研究人员开发了新型不对称的复合物,模仿酶进行高效的阿尔多尔反应. 这些催化剂能够精确合成复杂分子,具有出色的产量和立体选择性,推进非对称催化.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 不对称的合成方法
背景情况:
- 含的II类阿尔多酶是重要的生物催化剂.
- 开发这些酶的合成模仿剂是催化过程中的一个关键挑战.
研究的目的:
- 开发新型不对称的复合物,以模仿II类含的阿尔多拉酶.
- 在基基的直接催化不对称阿尔多尔反应中应用这些复合物.
主要方法:
- 开发具有 (S,S) 结合的BINOL连接体的二甲基 (Et(2) Zn) 复合体.
- 催化剂系统的优化,包括静电测量的变化和分子的使用.
- 使用X射线分析,NMR,CSI-MS和动力学研究的机械研究.
主要成果:
- 在阿尔多尔反应中,A Et(2) Zn/(S,S) 连接-BINOL 1 系统实现了高产率 (高达95%) 和优异的反选择性 (高达99%).
- 一个第二代系统 (Et(2)Zn/(S,S) -linked-BINOL 1 = 4/1与MS 3A) 在低催化剂负荷 (0.1 mol %) 的情况下表现出显著的效率.
- 该系统成功地创建了具有高产量和酶选择性的奇拉四替代碳中心.
结论:
- 开发的不对称复合物是直接阿尔多尔反应的高效催化剂.
- 优化的催化剂系统在催化剂加载方面提供了前所未有的效率.
- 这些发现为不对称的阿尔多尔反应的机制提供了新的见解,并促进了合成化学的发展.
相关概念视频
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.
Aldol 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.
Acid-Catalyzed Aldol Addition Reaction
The aldol reaction of a ketone under acidic conditions successfully forms an unsaturated carbonyl as the final product instead of an aldol. The acid-catalyzed aldol reaction is depicted in Figure 1.
Crossed Aldol Reaction Using Strong Bases: Directed Aldol Reaction
The reaction between two different carbonyl compounds comprising α hydrogen in the presence of a strong base like lithium diisopropylamide (LDA) to form a crossed aldol product is known as a directed aldol reaction. The directed aldol reaction is depicted in Figure 1.
Reduction 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...
Oxidation 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.


