电还原性烯酸联接
Pengfei Hu1,2, Byron K Peters1,2, Christian A Malapit3,2
1Department of Chemistry, Scripps Research, 10550 North Torrey Pines Road, La Jolla 92037, California, United States.
Journal of the American Chemical Society
|December 1, 2020
概括
这项研究引入了一种新的电化学方法,其中子作为核友来合成三级酒精. 这种用户友好的技术为传统的Grignard添加剂提供了可扩展和耐空/耐水的替代方案.
科学领域:
- 有机化学
- 合成方法
- 电化学
背景情况:
- 传统的格里纳德添加到未激活的是合成三级酒精的基石.
- 这种方法通常需要严格的无水和无氧条件,这限制了其实际应用.
- 开发替代的,用户友好的合成途径仍然是有机合成的一个重大挑战.
研究的目的:
- 提出一种新的,易于使用的方法,用未激活的和烯来合成三级酒精.
- 为了扭转典型的极性断开,使能作为核友.
- 建立一个可扩展的,化学选择的,强大的电化学方法来实现这种转化.
主要方法:
- 采用电化学方法来促进基的核友添加到未激活的氨酸中.
- 反应在范围,可扩展性和对空气和水的耐受性方面得到了优化.
- 进行了机制研究以阐明反应途径.
主要成果:
- 开发的电化学方法成功地将和简单的未激活的烯结合起来,产生三级酒精.
- 反应显示了广泛的范围,高化学选择性和可扩展性.
- 这一过程对空气和水具有耐受性,简化了实验程序.
结论:
- 这项研究在合成有机化学方面取得了重大进展,为格里纳德反应提供了一个用户友好的替代方案.
- 电化学方法简化了多步合成,在温和的条件下提供了三级酒精.
- 这种直观的机制与SmI2等传统的减少剂不同,突显了这种方法的新性.
相关概念视频
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The pinacol and McMurry reactions involve the reductive coupling of ketones or aldehydes. Similarly, the bimolecular reductive coupling of two ester molecules in the presence of sodium metal in an aprotic solvent yields an α-hydroxy ketone product. The α-hydroxy ketone is also called acyloin, so the reaction is referred to as ‘acyloin condensation.’
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01:27Vicinal Diols via Reductive Coupling of Aldehydes or Ketones: Pinacol Coupling Overview
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Wilhelm Rudolph Fittig discovered the pinacol coupling reaction in 1859. It is a radical dimerization reaction and involves the reductive coupling of aldehydes or ketones in the presence of hydrocarbon solvent to yield vicinal diols.
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01:22Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
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The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.
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01:27Aldol Condensation with β-Diesters: Knoevenagel Condensation
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01:15Acid-Catalyzed Aldol Addition Reaction
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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.
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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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