催化 (2 + 2) 烯的分子内循环添加
Moisés Gulías1, Alba Collado, Beatriz Trillo
1Departamento de Química Orgánica y Centro Singular de Investigación en Química Biológica y Materiales Moleculares, Unidad Asociada al CSIC, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Journal of the American Chemical Society
|April 30, 2011
概括
催化剂使得新的 (2 + 2) 和的分子内循环添加成为可能. 这种反应在温和的,散列选择性条件下,产生双环[3.2.0]结构与循环环.
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:
- 循环添加反应是有机合成中构建循环分子的基础.
- 复合物是已知的催化剂,但它们在 (2+2) 和的分子内循环添加中的应用仍未得到充分研究.
- 开发高效和有选择的方法来合成像循环butanes这样的应变环系统是非常有趣的.
研究的目的:
- 报告一种新的催化 (2 + 2) 内分子循环添加反应.
- 为了研究一个特定的复合物,RuH的有效性{2}Cl{2}P{i}Pr{3}{2}),在这种转化中.
- 为了建立一个实用的合成路径,以bicyclo[3.2.0]heptane衍生物.
主要方法:
- 使用复合物RuH(2)Cl(2)(P(i)Pr(3))(2) 作为催化剂.
- 利用阿伦和基因作为分子内循环添加的基质.
- 在温和的反应条件下进行反应.
- 分析立体化学结果以确定二聚体选择性.
主要成果:
- 成功证明了在阿和之间发生的催化 (2 + 2) 内分子循环添加.
- 识别RuH{2}Cl{2}P{i}Pr{3}) {2}作为这种反应的关键催化剂.
- 在温和的条件下,反应有效地进行.
- 循环添加是完全分立体选择的,产生特定的立体异构体.
- 提供对含有循环butan环的bicyclo[3.2.0]heptane骨的访问.
结论:
- 开发了一种新的催化合成方法,用于 (2 + 2) 内分子循环添加.
- 催化剂RuH{2}Cl{2}P{i}Pr{3}) 是实现高反应性和选择性的关键.
- 这种方法提供了一种实用且分类选择性的途径,以获得有价值的bicyclo[3.2.0]heptane结构.
相关概念视频
01:16Cycloaddition Reactions: Overview
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
01:27Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Robinson annulation is a base-catalyzed reaction for the synthesis of 2-cyclohexenone derivatives from 1,3-dicarbonyl donors (such as cyclic diketones, β-ketoesters, or β-diketones) and α,β-unsaturated carbonyl acceptors. Named after Sir Robert Robinson, who discovered it, this reaction yields a six-membered ring with three new C–C bonds (two σ bonds and one π bond).
01:16Cycloaddition Reactions: MO Requirements for Thermal Activation
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
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.
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.