Simultaneous sulfonylation/arylation of styrene derivatives is achieved in a photoredox‐catalyzed three‐component reaction using visible light. A broad variety of difunctionalized products is accessible in mostly excellent yields and high diastereoselectivity. The developed reaction is scalable and suitable for the modification of styrene‐functionalized biomolecules. Mechanistic investigations suggest the transformation to be operating through a designed sequence of radical formation and radical combination.
Photochemical processes, such as isomerizations and cycloadditions, have proven to be very useful in the construction of highly strained molecular frameworks. Photoinduced ring strain enables subsequent exergonic reactions which do not require the input of additional chemical energy and provides a variety of attractive synthetic options leading to complex structures. This review covers the progress achieved in the application of sequences combining excitation by ultraviolet light to form strained intermediates, which are further transformed to lower energy products in strain‐release reactions. As ring strain is considerable in small ring systems, photogenerated three‐ and four‐membered rings will be covered, mainly focusing on examples from 2000 to May 2020.
The first intermolecular visible light [3+2] cycloaddition reaction performed on a meta photocycloadduct employing acetylenic sulfones is described. The developed methodology exploits the advantages of combining UV and visible‐light in a two‐step sequence that provides a photogenerated cyclopropane which, through a strain‐release process, generates a new cyclopentane ring while significantly increasing the molecular complexity. Mechanistic studies and DFT calculations indicate an energy transfer pathway for the visible light‐driven reaction step. This strategy could be extended to simpler vinylcyclopropanes.
The simultaneous sulfonylation and arylation of styrene derivatives, including complex biomolecules, is achieved in an atom‐economic, operationally simple and scalable three‐component photoredox reaction. It allows for significant structural variation within each component and displays high diastereoselectivity. The cover depicts the double radical transformation catalyzed by Ir(ppy)3 under irradiation with visible light, resulting in the difunctionalized styrene, which is represented by its crystal structure (compound 20 in the paper). Sarah Susanne Part is thanked for the design of the cover art. More information can be found in the Communication by T. Opatz et al. on page 8965.
We describe the first intermolecular visible light [3+2] cycloaddition reaction being performed on a meta photocycloadduct employing acetylenic sulfones. The developed methodology exploits the advantages of combining UV and Visible light in a two-step sequence that provides a photogenerated cyclopropane which, through a strain-release process, generates a new cyclopentane ring while increasing significally the molecular complexity. This strategy could be extended to simpler vinylcyclopropanes.
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