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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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Arylazo Sulfones as Nonionic Visible-Light Photoacid Generators
Lorenzo Di Terlizzi1, Angelo Martinelli2, Daniele Merli2
1PhotoGreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy.
The Journal of Organic Chemistry
|July 22, 2022
Summary
Shelf-stable arylazo sulfones enable visible-light-driven acid generation for green alcohol protection. This photochemical method efficiently forms tetrahydropyranyl ethers and acetals under mild conditions.
Area of Science:
- Organic Chemistry
- Photochemistry
- Green Chemistry
Background:
- Arylazo sulfones are versatile reagents in organic synthesis.
- Visible-light photochemistry offers sustainable synthetic routes.
- Protection of alcohols and phenols is crucial in multi-step synthesis.
Purpose of the Study:
- To develop a selective visible-light-driven method for generating sulfinic and sulfonic acids.
- To utilize these generated acids for the photochemical catalytic protection of alcohols and phenols.
- To establish a green, efficient, and smooth protocol for forming tetrahydropyranyl ethers and acetals.
Main Methods:
- Visible-light irradiation of arylazo sulfones in nitrogen- or oxygen-purged solutions.
- Photochemical catalysis using the in situ generated acids.
- Reaction of various substituted alcohols and phenols with dihydropyran.
Main Results:
- Selective generation of sulfinic acid (N2) or sulfonic acid (O2) under visible light.
- Efficient protection of diverse alcohols and phenols as tetrahydropyranyl ethers or acetals.
- High yields and chemoselectivity achieved under mild, green conditions.
Conclusions:
- Arylazo sulfones are effective precursors for visible-light-mediated acid generation.
- The developed method provides a sustainable and efficient approach for alcohol and phenol protection.
- This photochemical strategy offers a valuable tool for synthetic organic chemistry.
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