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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
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Organophotoredox-Catalyzed Intermolecular Oxa-[4+2] Cycloaddition Reactions
Kenta Tanaka1, Daichi Omata1, Yosuke Asada1
1Graduate School of Environment and Information Sciences , Yokohama National University , Tokiwadai , Hodogaya-ku, Yokohama 240-8501 , Japan.
The Journal of Organic Chemistry
|July 20, 2019
Summary
A new green light-promoted reaction enables oxa-[4+2] cycloadditions using a thioxanthylium photoredox catalyst. This sustainable method efficiently converts ortho-quinone methides and styrenes into valuable cycloadducts.
Area of Science:
- Organic Chemistry
- Photocatalysis
- Green Chemistry
Background:
- Oxa-[4+2] cycloaddition reactions are crucial for synthesizing heterocyclic compounds.
- Developing sustainable and efficient catalytic methods for these transformations remains an active research area.
Purpose of the Study:
- To develop a novel, light-promoted intermolecular oxa-[4+2] cycloaddition reaction.
- To utilize a thioxanthylium photoredox catalyst for enhanced reaction efficiency and sustainability.
Main Methods:
- Employing a thioxanthylium photoredox catalyst.
- Utilizing green light irradiation to drive the cycloaddition.
- Reacting ortho-quinone methides with various styrenes.
Main Results:
- The developed method successfully promotes intermolecular oxa-[4+2] cycloaddition reactions.
- The reaction proceeds smoothly, affording the desired cycloadducts.
- Styrenes substituted with electron-donating groups show particularly high efficiency in the transformation.
Conclusions:
- This work presents a sustainable approach to oxa-[4+2] cycloaddition reactions.
- The method relies on catalytic amounts of a photocatalyst and visible light, aligning with green chemistry principles.
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01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
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