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Photochemical Boronate Rearrangement Enables the One-Pot Synthesis of 2,4-Difunctionalized 2H-Chromenes
Chenyang Xu1, Yixin Zhang1, Yiyun Chen1,2,3
1State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
This study introduces a new, one-pot method using visible light to synthesize 2H-chromenes from 2-hydroxychalcones and organoboronic acids. This efficient photochemical strategy offers a greener alternative for creating valuable pharmaceutical building blocks.
Area of Science:
- Organic Chemistry
- Photochemistry
- Medicinal Chemistry
Background:
- 2H-Chromenes are crucial scaffolds in pharmaceuticals.
- Traditional synthesis methods for 2H-chromenes are often inefficient, requiring multiple steps or harsh conditions.
Purpose of the Study:
- To develop a novel, one-pot, visible-light-mediated synthesis of 2,4-disubstituted 2H-chromenes.
- To provide modular access to diverse 2H-chromene derivatives, including challenging motifs.
Main Methods:
- Utilizing a photochemical 1,3-boronate rearrangement.
- Employing a visible-light-mediated reaction between 2'-hydroxychalcones and organoboronic acids.
- Implementing the protocol in a continuous-flow system for scalability.
Main Results:
- Successfully synthesized diverse 2,4-disubstituted 2H-chromenes.
- Achieved high regioselectivity via 1,2-addition, avoiding typical 1,4-addition pathways.
- Demonstrated broad functional group compatibility and synthesized 40 examples, including 2-alkyl-4-aryl motifs.
Conclusions:
- The developed photochemical strategy offers an efficient and modular route to valuable 2H-chromene scaffolds.
- The continuous-flow implementation enhances reaction time and facilitates gram-scale synthesis, showcasing practical applicability.
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