分子间/分子内连续的阿尔多尔反应
Atsuto Izumiseki1, Hisashi Yamamoto
1Molecular Catalyst Research Center, Chubu University , 1200 Matsumoto-cho, Kasugai 487-8501, Japan.
Journal of the American Chemical Society
|January 17, 2014
概括
这项研究引入了一种使用disiyl enol乙烯的新型序列性阿尔多尔反应. 这种方法有效地创建复杂的循环分子与精确的立体化学控制.
科学领域:
- 有机化学 有机化学
- 合成化学 合成化学
背景情况:
- 阿尔多尔反应在有机合成中对于碳-碳键的形成至关重要.
- 控制 aldol 反应中的立体化学对于合成复杂分子至关重要.
研究的目的:
- 描述第一个分子间/分子内序列阿尔多尔反应的迪西乙醇.
- 为了证明五,六,七个环的产品的形成.
- 在创建多个立体中心时,实现高水平的相对立体化学控制.
主要方法:
- 在一个顺序的阿尔多尔反应中利用disiylenole.
- 采用促进分子间和分子内反应通路的条件.
- 分析反应产物以确定环形大小和立体化学.
主要成果:
- 成功执行了第一个分子间/分子内序列的阿尔多尔反应与迪西乙醇乙.
- 形成各种循环产物,包括五,六和七个环.
- 产生四个或更多连续的立体中心,具有较高的相对立体化学控制.
结论:
- 开发的顺序阿尔多尔反应策略对于构建复杂的循环支架是有效的.
- 这种方法为立体选择性合成提供了一个强大的工具.
- 反应提供了与可预测立体化学的复杂分子架构的访问.
相关概念视频
01:18Intramolecular Aldol Reaction
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Intramolecular aldol reaction occurs in dicarbonyl compounds such as dialdehydes, diketones, and keto-aldehydes. The dicarbonyl compounds possess more than one nucleophilic ⍺ carbon for the base to deprotonate and form the enolates. For example, in symmetrical diketones, there are four ⍺ carbons. Hence, four types of enolates are possible when treated with a base. However, since the molecule is symmetrical, the enolates formed on either side of one carbonyl group are equivalent to...
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01:10C–C Bond Formation: Aldol Condensation Overview
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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.
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01:08Base-Catalyzed Aldol Addition Reaction
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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.
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00:56Crossed Aldol Reaction Using Strong Bases: Directed Aldol Reaction
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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.
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01:04Crossed Aldol Reactions: Overview
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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.
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00:57C–C Bond Cleavage: Retro-Aldol Reaction
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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.
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