通过光反催化原子转移和选择性质子进行非对称的素异构
在PubMed上查看摘要
概括
此摘要是机器生成的。这项研究引入了一种新型的光反氧催化方法,用于不对称的烯酸异构化,使得有价值的烯酸丰富分子的合成成为可能. 这种策略克服了热力学限制,扩大了有机合成的可能性.
科学领域
- 有机化学
- 催化剂
- 不对称的合成
背景情况
- 不对称的olefin同质化是一种有价值的合成途径.
- 由于热力学优势的要求 (产品在基板上的稳定性) 取得了有限的成功.
研究的目的
- 开发一种策略来挑战具有热力学不利的不对称烯酸异构.
- 用α-三级碳立体中心合成富含酸衍生物.
主要方法
- 使用双催化剂系统与可见光光敏感剂 (DPZ) 和酸.
- 使用N-氧胺的光反氧催化原子转移 (HAT).
- 使用D2O作为立体中心标签的源.
主要成果
- 已经成功合成了多种类型的酸衍生物.
- 实现了高产量,反体过量 (ee) 和E/Z比率.
- 在立体中心体现了的结合.
结论
- 开发的策略可以实现热力学不利的不对称烯酸异构.
- 该方法在合成复杂分子方面具有广泛的适用性和有前途的实用性.
- 机理性见解提供了对反应性和反选择性挑战的理解.
相关概念视频
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...
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.
Syn Dihydroxylation Mechanism
The reaction comprises a two-step mechanism. It begins with the addition of osmium tetroxide across the alkene double bond in a concerted manner forming a...
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.
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A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
Borane as a reagent is very reactive, as the...

