alkene photocycloaddition

https://doi.org/10.1351/goldbook.AT07318
Photochemical process leading to formation of a cyclobutane upon addition of an electronically excited alkene to another ground-state alkene or of an electronically excited α,β-unsaturated carbonyl compound to a ground-state alkene. The latter is called a de Mayo reaction.
Note:
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Source:
PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 301 (https://doi.org/10.1351/pac200779030293)