通过路易斯和布伦斯特德酸协同协助氧化物的不对称化
在PubMed上查看摘要
概括
此摘要是机器生成的。这项研究提出了一种新型的催化不对称的氧化物到氧胺的化,克服了以前的挑战. 这种新方法使用易斯和布伦斯特德酸合作策略实现了高产量和反选择性.
科学领域
- 有机化学
- 催化剂
- 不对称的合成
背景情况
- 氧化物的催化不对称化到氧胺是具有挑战性的,因为其反应性较低,难以控制和N-O键裂变.
- 在有机化学中开发高效的胺合成方法至关重要.
研究的目的
- 建立一个易斯和布伦斯特德酸合作策略,用于氧化物的不对称化.
- 在基胺的合成中实现高产量和反选择性.
主要方法
- 使用一种合作催化系统,涉及易斯酸 (In ((OTf) 3或Zn ((OAc) 2) 和布伦斯特德酸 (l-CSA) 与基氨酸基.
- 进行机械研究以了解催化剂组件的作用.
主要成果
- 在氧化物不对称的化过程中,可获得高达95%的产量和96%的化过量 (ee).
- 证明了易斯和布伦斯特德酸在控制反应性和反选择性的关键作用.
- 成功地将反应扩大到格拉姆尺度,并保留了产量和酶选择性.
结论
- 开发的易斯和布伦斯特德酸合作战略有效地解决了氧化的挑战.
- 这种方法提供了一种强大的可扩展的途径,以化丰富.
相关概念视频
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...
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...
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.
The observed regioselectivity can be explained based on the radical stability and steric effect. From the radical stability perspective, adding hydrogen bromide in the presence of peroxide directs the bromine radical at the less substituted carbon via a more stable tertiary radical intermediate. Similarly, in the steric framework, the...
The reaction of hydrogen bromide with alkenes in the presence of hydroperoxides or peroxides proceeds via anti-Markovnikov addition. The radical chain reaction comprises initiation, propagation, and termination steps.
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy...
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
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...

