相关实验视频

Updated: Oct 11, 2025

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species

Published on: August 16, 2018

可调节和实用的同质有机减速剂

David J Charboneau¹, Haotian Huang¹, Emily L Barth¹

¹Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States.

Journal of the American Chemical Society

|November 30, 2021

概括

为金属介导反应合成了四种新的稳定在空气中的有机减少剂. 这些可调节的减速剂为交叉电友合 (XEC) 反应提供了增强的稳定性和控制,使新的合成策略成为可能.

科学领域:

有机化学
合成化学
催化剂

背景情况:

均质的减电剂对于金属介导的减电转换,如交叉电友合 (XEC) 是至关重要的.
现有的减速剂往往具有不良的空气稳定性和有限的可调性,这阻碍了它们的广泛应用.
需要强大且多功能的减少剂,使反应条件更温和,基质范围更广.

研究的目的:

合成和描述基于四氨基乙烯支架的新型,空气稳定,均的有机减少剂.
评估这些新减少剂在促进具有挑战性的Ni-催化C-sp2-C-sp3交叉电友合反应中的有效性.
通过调整减氧潜力来开发一种控制基生成的新策略.

主要方法:

合成四种新的四氨基乙烯基有机减少剂,具有可调节的氧化还原潜力.
对合成的减速剂的空气稳定性和减速潜力的评估 (与铁素对比).
减少剂在涉及卡特里茨基盐和化的Ni-催化C(sp2) -C(sp3) 交叉电友合反应中的应用.

主要成果:

新的减电剂表现出增强的空气稳定性,其中一个在空气中无限期稳定 (-0.85V对Fc).
所有合成的还原剂都有效地促进了Ni-催化C ((sp2) -C ((sp3) XEC反应,即使是复杂的基质.
通过调整减氧剂和卡特里茨基盐的氧化还原潜力,证明了一种控制基生成的新方法,使具有挑战性的XEC转换成为可能.

结论:

开发的以四氨基乙烯为基础的减少剂为传统的同质减少剂提供了稳定和可调节的替代品.
这些还原剂促进了更温和,更可控的Ni-催化还原转化,包括C(sp2) -C(sp3) XEC.
这些减速剂的可调性为开发新合成方法和扩大减速合反应的范围开辟了道路.

更多相关视频

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions

Published on: March 20, 2014

Retropinacol/Cross-pinacol Coupling Reactions - A Catalytic Access to 1,2-Unsymmetrical Diols

Retropinacol/Cross-pinacol Coupling Reactions - A Catalytic Access to 1,2-Unsymmetrical Diols

Published on: April 4, 2014

相关概念视频

Thermal and Photochemical Electrocyclic Reactions: Overview

Thermal and Photochemical Electrocyclic Reactions: Overview

Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.

Photochemical Electrocyclic Reactions: Stereochemistry

Photochemical Electrocyclic Reactions: Stereochemistry

The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation

Thermal Electrocyclic Reactions: Stereochemistry

Thermal Electrocyclic Reactions: Stereochemistry

The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.

Crossed Aldol Reactions: Overview

Crossed Aldol Reactions: Overview

Crossed aldol addition is the reaction between two different carbonyl compounds under acidic or basic conditions. Here, both the carbonyl compounds function as nucleophiles and electrophiles. As shown in Figure 1, such a reaction yields a mixture of products, two of which are formed via self-condensation, while the remaining two are formed via crossed-condensation. Without adjustment, the reaction's usefulness in organic chemistry is decreased.

Cycloaddition Reactions: Overview

Cycloaddition 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.

Pericyclic Reactions: Introduction

Pericyclic Reactions: Introduction

Pericyclic reactions are organic reactions that occur via a concerted mechanism without generating any intermediates. The reactions proceed through the movement of electrons in a closed loop to form a cyclic transition state, where rearrangement of the σ and π bonds yields specific products.
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic...