通过双组分半乙/氧结合物添加反应的双组分 bismuth 中介的 syn-1,3-dioxanes 的灾难选择性构造
P Andrew Evans1, Aleksandr Grisin, Michael J Lawler
1Department of Chemistry, The University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom. Andrew.Evans@liverpool.ac.uk
Journal of the American Chemical Society
|February 3, 2012
概括
这项研究介绍了一种简单,高效的甲催化反应,以产生syn-1,3-dioxanes. 该方法直接形成有价值的电子吸收组,简化了合成途径.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 合成方法论 合成方法论
背景情况:
- 复杂有机分子的立体选择合成在药物发现和材料科学中至关重要.
- 开发高效的催化方法来构建1,3-二氧化等异环化合物仍然是一个活跃的研究领域.
- 石催化提供了一种更绿色,往往更有选择性的替代传统重金属催化剂.
研究的目的:
- 开发一种新的,高效的,立体选择性的方法来合成syn-1,3-dioxanes.
- 探讨在两组分半乙/氧结合物添加反应中土催化物的实用性.
- 为了证明电子吸收组的直接引入而不需要氧化状态调整.
主要方法:
- 使用卜素催化剂调节δ-三基化/δ-化α,β-不和化和化之间的反应.
- 采用两组分反应策略,涉及半乙的形成,然后添加氧-合物.
- 通过使用标准光谱技术,对产生的 syn-1,3-二氧化物产品进行了表征.
主要成果:
- 实现了syn-1,3-dioxanes的高效和立体选择性合成.
- 展示了开发的协议的操作简单性.
- 成功地直接访问了带有电子吸收组的分子,避免了多步氧化过程.
结论:
- 这种以木为媒介的反应提供了一条强大而简单的途径,以获得有价值的syn-1,3-二氧化衍生物.
- 这种方法在效率,立体选择性和合成融合方面提供了显著的优势.
- 该协议直接安装功能组的能力简化了复杂分子合成.
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相关概念视频
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
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.
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
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.
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01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
03:00Preparation of Epoxides
Overview
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
01:28Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.
02:36Regioselectivity and Stereochemistry of Hydroboration
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 stereochemistry.
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 stereochemistry.