催化性对子进行enantioselective aldol反应的催化反应
Kounosuke Oisaki1, Dongbo Zhao, Motomu Kanai
1Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan.
Journal of the American Chemical Society
|June 1, 2006
概括
这项研究引入了一种新型的催化系统,用于和 ketene silyl acetals 之间的 enantioselective aldol 反应. 开发的铜化物-奇拉氨酸催化剂实现了对各种基质的高选择性.
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:
- 阿尔多尔反应是基本的碳-碳键形成反应.
- 在涉及和 ketene silyl acetals 的 aldol 反应中实现高的 enantioselectivity 仍然是一个挑战.
- 开发高效的催化系统对于可持续合成至关重要.
研究的目的:
- 开发一种新型的催化系统,用于和 ketene silyl acetals 之间的 enantioselective 和 diastereoselective aldol 反应.
- 研究一种新联体和添加剂在实现高选择性的作用.
- 为了证明开发的方法的广泛适用性.
主要方法:
- 使用一种化铜 (CuF) 复合物与一种来自Taniaphos的新性氨酸接体.
- 作为加快剂添加剂使用二二酸 (PhBF3K).
- 测试了各种各样的芳香基,阿利法基和异芳香基的反应,以及替代的核爱素.
主要成果:
- 在和 ketene silyl acetals 之间的 aldol 反应中实现了高的 enantioselectivity.
- 新型的taniaphos衍生联体和phbf3k添加剂是高反选择性的关键.
- 催化系统展示了广泛的基质范围,包括各种类型和替代核.
- 发现灾难选择性是独立于 ketene silyl acetal 几何的.
结论:
- 这项工作展示了子与基烯乙烯的催化和二聚选择性阿尔多尔反应的第一个例子.
- 开发的CuF-奇拉胺催化系统为不对称合成提供了一个强大的新工具.
- 该方法是高效的,适用于广泛的基质,为复杂分子合成铺平了道路.
相关概念视频
01:08Base-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.
00:56Crossed 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.
01:15Acid-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.
00:57C–C Bond Cleavage: Retro-Aldol Reaction
The reverse of the aldol addition reaction is called the retro-aldol reaction. Here, the carbon–carbon bond in the aldol product is cleaved under acidic or basic conditions to form two molecules of carbonyl compounds. The mechanism of the reaction consists of three steps.
In the first step, as depicted in Figure 1, the base deprotonates the β-hydroxy ketone at the hydroxyl group to form an alkoxide ion.
In the first step, as depicted in Figure 1, the base deprotonates the β-hydroxy ketone at the hydroxyl group to form an alkoxide ion.
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.
01:33Aldol Condensation vs Claisen Condensation
Aldol condensation is an acid or base-catalyzed condensation between aldehydes or ketones to give an α,ꞵ-unsaturated carbonyl compound. A base-promoted condensation between ester molecules to produce a ꞵ-ketoester is known as the Claisen condensation. In the presence of a base, both reactions involve deprotonation of the acidic α hydrogen to produce the corresponding enolates. The nucleophilic enolates attack their respective nonenolized carbonyl compound forming a tetrahedral intermediate.