Related Experiment Video
Updated: Jan 11, 2026
07:36
Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
Published on: November 9, 2019
8.4K
Cu-catalyzed enantioconvergent oxygen-centered radical cyclization
Zhen-Yu Li1, Chun-Dong Huang2, Chun-Yan Guan1
1College of Chemistry (Pingyuan Laboratory), Zhengzhou University Zhengzhou 450001 China gaobeiling@zzu.edu.cn meigj@zzu.edu.cn.
Chemical Science
|November 12, 2025
Summary
This study introduces a novel copper-catalyzed method for enantioconvergent oxygen-centered radical cyclization. The reaction efficiently creates valuable isoxazolines with high enantioselectivity from racemic precursors.
Area of Science:
- Organic Chemistry
- Catalysis
- Asymmetric Synthesis
Background:
- Radical cyclization is crucial for synthesizing ring structures.
- Asymmetric cyclization of oxygen-centered radicals is challenging due to their reactivity.
- Existing methods for carbon-centered radical cyclization are more advanced.
Purpose of the Study:
- To develop an enantioselective method for oxygen-centered radical cyclization.
- To address the challenges associated with the high oxidizing power and electrophilicity of oxygen-centered radicals.
- To synthesize valuable isoxazoline compounds with high enantiopurity.
Main Methods:
- Cu-catalyzed asymmetric oxidative coupling reaction.
- Utilizing the tertiary C(sp3)-H bond and oxime O-H bond of racemic γ-ketoximes.
- Employing aerobic and mild reaction conditions.
Main Results:
- Achieved enantioconvergent oxygen-centered radical cyclization.
- Synthesized a diverse range of isoxazolines with a fully substituted stereocenter.
- Obtained good yields and excellent enantioselectivity.
Conclusions:
- The developed method provides an efficient route to enantiomerically enriched isoxazolines.
- Mechanistic studies elucidated the origin of enantiocontrol.
- Demonstrated synthetic utility through transformation into polyhydroxy building blocks.
Related Concept Videos
01:25Radical Anti-Markovnikov Addition to Alkenes: Overview
4.0K
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.
4.0K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.8K
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 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...
3.8K
03:00Preparation of Epoxides
9.1K
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...
9.1K
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.5K
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.
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.
2.5K
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
7.2K
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.
7.2K
01:33Radical Reactivity: Intramolecular vs Intermolecular
2.1K
Radical reactions can occur either intermolecularly or intramolecularly. In an intermolecular radical reaction, a nucleophilic radical adds to an electrophilic alkene or vice versa. In such reactions, the radical and generally the alkene, which is also called the radical trap, are two different molecules. Additionally, for such intermolecular reactions to occur, the radical trap must be active, present in an excess concentration, and the radical starting material must have a weak...
2.1K