Photocyclization of Alkenes and Arenes: Penetrating Through Aromatic Armor with the Help of Excited State Antiaromaticity

This review focuses on photocyclization reactions involving alkenes and arenes. Photochemistry opens up synthetic opportunities difficult for thermal methods, using light as a versatile tool to convert stable ground-state molecules into their reactive excited counterparts. This difference can be par...

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Main Authors: Nikolas R. Dos Santos, Judy I. Wu, Igor V. Alabugin
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Chemistry
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Online Access:https://www.mdpi.com/2624-8549/7/3/79
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author Nikolas R. Dos Santos
Judy I. Wu
Igor V. Alabugin
author_facet Nikolas R. Dos Santos
Judy I. Wu
Igor V. Alabugin
author_sort Nikolas R. Dos Santos
collection DOAJ
description This review focuses on photocyclization reactions involving alkenes and arenes. Photochemistry opens up synthetic opportunities difficult for thermal methods, using light as a versatile tool to convert stable ground-state molecules into their reactive excited counterparts. This difference can be particularly striking for aromatic molecules, which, according to Baird’s rule, transform from highly stable entities into their antiaromatic “evil twins”. We highlight classical reactions, such as the photocyclization of stilbenes, to show how alkenes and aromatic rings can undergo intramolecular cyclizations to form complex structures. When possible, we explain how antiaromaticity develops in excited states and how this can expand synthetic possibilities. The review also examines how factors such as oxidants, substituents, and reaction conditions influence product selectivity, providing useful insights for improving reaction outcomes and demonstrating how photochemical methods can drive the development of new synthetic strategies.
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spelling doaj-art-241b3350cbeb4a0fb339b3dfcbd901092025-08-20T02:24:19ZengMDPI AGChemistry2624-85492025-05-01737910.3390/chemistry7030079Photocyclization of Alkenes and Arenes: Penetrating Through Aromatic Armor with the Help of Excited State AntiaromaticityNikolas R. Dos Santos0Judy I. Wu1Igor V. Alabugin2Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USADepartment of Chemistry, University of Houston, Houston, TX 77204, USADepartment of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USAThis review focuses on photocyclization reactions involving alkenes and arenes. Photochemistry opens up synthetic opportunities difficult for thermal methods, using light as a versatile tool to convert stable ground-state molecules into their reactive excited counterparts. This difference can be particularly striking for aromatic molecules, which, according to Baird’s rule, transform from highly stable entities into their antiaromatic “evil twins”. We highlight classical reactions, such as the photocyclization of stilbenes, to show how alkenes and aromatic rings can undergo intramolecular cyclizations to form complex structures. When possible, we explain how antiaromaticity develops in excited states and how this can expand synthetic possibilities. The review also examines how factors such as oxidants, substituents, and reaction conditions influence product selectivity, providing useful insights for improving reaction outcomes and demonstrating how photochemical methods can drive the development of new synthetic strategies.https://www.mdpi.com/2624-8549/7/3/79photocyclizationantiaromaticityarenes
spellingShingle Nikolas R. Dos Santos
Judy I. Wu
Igor V. Alabugin
Photocyclization of Alkenes and Arenes: Penetrating Through Aromatic Armor with the Help of Excited State Antiaromaticity
Chemistry
photocyclization
antiaromaticity
arenes
title Photocyclization of Alkenes and Arenes: Penetrating Through Aromatic Armor with the Help of Excited State Antiaromaticity
title_full Photocyclization of Alkenes and Arenes: Penetrating Through Aromatic Armor with the Help of Excited State Antiaromaticity
title_fullStr Photocyclization of Alkenes and Arenes: Penetrating Through Aromatic Armor with the Help of Excited State Antiaromaticity
title_full_unstemmed Photocyclization of Alkenes and Arenes: Penetrating Through Aromatic Armor with the Help of Excited State Antiaromaticity
title_short Photocyclization of Alkenes and Arenes: Penetrating Through Aromatic Armor with the Help of Excited State Antiaromaticity
title_sort photocyclization of alkenes and arenes penetrating through aromatic armor with the help of excited state antiaromaticity
topic photocyclization
antiaromaticity
arenes
url https://www.mdpi.com/2624-8549/7/3/79
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AT igorvalabugin photocyclizationofalkenesandarenespenetratingthrougharomaticarmorwiththehelpofexcitedstateantiaromaticity