Photochemical Reactions. Photochemistry of α,β-Unsaturated δ,ε-Epoxyketones of the Ionone Series

Article abstract of DOI:10.1002/hlca.19850680124

On n,?*- as well as on ?,?*-excitation, the 4,5-epoxy-α-ionones (E)-1, (E)-2, and (E)-3 undergo (E)/(Z)-isomerization and subsequent γ-H-abstraction leading to the corresponding 4-hydroxy-β-ionones (E/Z)-9, E/Z)-13, and (E/Z)-17 as primary photoproducts.On photolysis of (E)-3, as an additional primary photoproduct, the β,γ-unsaturated δ,ε-epoxy ketone 18 was obtained.The other isolated compounds, namely the 2H-pyrans 10A+B and 14A+B as well as the retro-γ-ionones 11 and 15A+B, represent known types of products which are derived from the 4-hydroxy-β-ionones (E/Z)-9 and (E/Z)-13, respectively.