EnT-catalysis-enabled, radical-relay cascade cyclization to access multisubstituted cyclohexane/cyclohexene.
Mei Xiang1, Cong Huang1, Jie Gao1
1College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China. hyangchem@csu.edu.cn.
Chemical Communications (Cambridge, England)
|December 24, 2025
Summary
Visible-light-mediated triplet-triplet energy transfer (EnT) catalysis enables efficient synthesis of multisubstituted cyclohexane and cyclohexene frameworks. This novel radical-relay cyclization strategy utilizes a bifunctional reagent for broad substrate scope and high diastereoselectivity.
Area of Science:
- Organic Chemistry
- Catalysis
- Photochemistry
Background:
- Visible-light photocatalysis is a rapidly growing field.
- Triplet-triplet energy transfer (EnT) catalysis offers unique reactivity pathways.
- Developing efficient methods for synthesizing complex cyclic frameworks is crucial.
Purpose of the Study:
- To develop a novel EnT-catalyzed radical-relay cyclization strategy.
- To synthesize diverse multisubstituted cyclohexane and cyclohexene frameworks.
- To explore the utility of a rationally designed bifunctional reagent.
Main Methods:
- Visible-light irradiation.
- Triplet-triplet energy transfer (EnT) catalysis.
- Radical-relay cyclization.
- Utilized a novel bifunctional reagent: diphenylmethane O-(2,2-dimethyl-4-phenylpent-4-enyl) oxime.
Main Results:
- Successful synthesis of various multisubstituted cyclohexane and cyclohexene frameworks.
- Demonstrated broad substrate scope with alkenes and alkynes.
- Achieved excellent diastereoselectivity in the cyclization reactions.
- Showcased facile conversion of cyclohexane products to 6-azabicyclo[3.2.1]octan-7-one derivatives.
Conclusions:
- The developed EnT-catalyzed radical-relay cyclization is a concise and effective method.
- The bifunctional reagent serves as dual radical precursors for efficient transformations.
- This approach provides an environmentally friendly route to complex cyclic molecules.
More Related Videos
Related Concept Videos
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
01:16Cycloaddition Reactions: Overview
3.3K
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.
3.3K
01:16Cycloaddition Reactions: MO Requirements for Thermal Activation
4.1K
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.
4.1K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
2.9K
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.
2.9K
01:11Radical Reactivity: Overview
2.6K
Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired...
2.6K
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