有机合成中的压力环:双 aldol-allylation 反应反应
Xiaolun Wang1, Qinglin Meng, Andrew J Nation
1Department of Chemistry, Columbia University, New York, NY 10027, USA.
Journal of the American Chemical Society
|September 5, 2002
概括
化学家们开发了一种使用循环基基基基和基的合基合反应. 这种高效的方法产生复杂的多基片段,形成多个碳-碳键和立体中心.
科学领域:
- 有机化学 有机化学
- 合成化学 合成化学
- 立体选择性合成 立体选择性合成
背景情况:
- 聚克化物碎片是天然产品合成中的关键构建块.
- 构建这些碎片的现有方法可能是复杂和低效的.
- 基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基
研究的目的:
- 开发一种高效和立体选择的方法来合成多基基片段.
- 为了探索紧张的循环基基基基基基基基基基基基基基基基基基基合反应中的反应性.
- 为创建多个碳-碳键和立体中心建立一个简单的路线.
主要方法:
- 基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基
- 使用应变释放易斯酸性固有的西兰试剂.
- 反应产品的表征,以确认结构和立体化学.
主要成果:
- 协同发生的 aldol-allylation 反应有效地进行,产生所需的多基基片段.
- 这种反应在单个合成过程中建立了两个新的碳-碳键.
- 在高度控制下生成多达四个新的立体中心.
- 锡兰试剂易于制备,并表现出储存的稳定性.
结论:
- 开发的合 aldol-allylation 反应提供了一个强大而高效的工具,用于聚基化合成.
- 使用应力循环西兰为立体选择性碳-碳键形成提供了一种独特的方法.
- 这种方法简化了复杂分子架构的构建,在药物化学和药物发现中具有价值.
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.
01:10C–C Bond Formation: Aldol Condensation Overview
Aldol condensation is an important route in synthetic organic chemistry used to generate a new carbon–carbon bond under basic or acidic conditions. The aldol condensation reaction presented in Figure 1 constitutes an aldol addition reaction followed by the dehydration process.
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.
01:04Crossed Aldol Reactions: Overview
Crossed aldol addition is the reaction between two different carbonyl compounds under acidic or basic conditions. Here, both the carbonyl compounds function as nucleophiles and electrophiles. As shown in Figure 1, such a reaction yields a mixture of products, two of which are formed via self-condensation, while the remaining two are formed via crossed-condensation. Without adjustment, the reaction's usefulness in organic chemistry is decreased.
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.