Benzotriazolyl Radical-Mediated C(sp3)-H Functionalization under Visible-Light Irradiation.
Quynh H Nguyen1, Seunghoon Shin1
1Department of Chemistry and Research Institute for Natural Sciences, Hanyang University, Seoul 04763, South Korea.
Organic Letters
|June 1, 2026
Summary
Benzotriazolyl radicals efficiently mediate selective C-H functionalization of ethers via hydrogen atom transfer. This visible-light-driven method enables the synthesis of valuable β-alkoxy ketones and coupled products.
Area of Science:
- Organic Chemistry
- Photochemistry
- Radical Chemistry
Background:
- Selective C(sp3)-H functionalization is crucial in organic synthesis.
- Traditional methods for ether functionalization often lack selectivity or require harsh conditions.
- Benzotriazole radicals offer unique properties for mediating radical reactions.
Purpose of the Study:
- To develop a visible-light-induced method for selective α-C(sp3)-H functionalization of ethers.
- To utilize benzotriazolyl radicals as efficient hydrogen atom transfer mediators.
- To explore the application of this methodology in synthesizing β-alkoxy ketones and coupled products.
Main Methods:
- Photochemical generation of benzotriazolyl radicals from N-enoxybenzotriazoles using visible light.
- Hydrogen atom transfer from ethers to benzotriazolyl radicals.
- Radical addition of α-alkoxy radicals to N-enoxybenzotriazoles or electron-deficient olefins.
Main Results:
- Selective abstraction of α-hydrogens from various ethers, thioethers, thioacetals, and benzylic positions.
- Efficient synthesis of β-alkoxy ketones as aldol surrogates with high radical chain propagation efficiency (Φ = 291).
- Successful three-component radical addition reactions yielding coupled products with high chemoselectivity.
Conclusions:
- Visible-light-induced photolysis of N-enoxybenzotriazoles provides a practical route to benzotriazolyl radicals.
- Benzotriazolyl radicals are effective mediators for selective α-C(sp3)-H functionalization of ethers.
- The developed protocol offers a versatile and efficient approach for constructing complex organic molecules.
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