Term: aromatic photocycloaddition
https://doi.org/10.1351/goldbook.AT07327

Definition:
Inter- and intramolecular photochemical processes involving the addition of a C–C double (or triple) bond (i) to the 1,2-positions of an arene in which case it is called an ortho photocycloaddition, with formation of a benzocyclobutene (or a benzocyclobutadiene) derivative, (ii) to the 1,3-positions of an arene in which case it is called a meta photocycloaddition, with formation of tricyclo[3.3.0.02,8]oct-3-ene (or octa-3,6-diene) derivatives, or (iii) to the 1,4-positions of an arene in which case it is called a para photocycloaddition, with formation of bicyclo[2,2,2]oct-2-ene (or octa-2,5-diene) derivatives.

Related Terms:
1) intramolecular (http://doi.org/10.1351/goldbook.I03130).
2) photocycloaddition (http://doi.org/10.1351/goldbook.PT07451).

Source: PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 303 (https://doi.org/10.1351/pac200779030293)

Citation: 'aromatic photocycloaddition' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.AT07327

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