Photochemical Reactions 127th CommunicationPhotochemistry of Epoxy‐enones: Intramolecular Trapping of a Carbonyl Ylide

Abstract On 1 n, π* ‐excitation 5, 6‐epoxy‐2‐hydroxy‐5, 6‐dihydro‐β‐ionone (( E )‐4) shows the typical behaviour of a, β‐unsaturated γ, δ‐epoxy ketones undergoing primarily C(γ), O‐cleavage of the oxiran. However, 1 π, π*‐excitation of ( E )− 4 leads to enol ether 10 which is formed by intramolecular insertion of the hydroxyl group of the ylide c .