Photochemische Reaktionen 119. Mitteilung [1] Zur Photospaltung konjugierter γ,δ‐Epoxyenone. UV.‐Bestrahlung von 3‐(1′,2′‐Epoxy‐2′‐methyl‐prop‐1′‐yl)‐5,5‐dimethyl‐2‐cyclohexen‐1‐on

Photocleavage of Conjugated π,π‐Epoxyenones. UV.‐Irradiation of 3‐(1′,2′‐Epoxy‐2′‐methyl‐prop‐1′‐yl)‐5,5‐dimethyl‐2‐cyclohexene‐1‐one On 1 π,π*‐excitation (δ = 254 nm) 9 undergoes cleavage of the C(δ), C(δ)‐bond yielding 17 and a , which gives 18 by photofragmentation. In presence of maleinic ester the photolysis of 9 yields 20 , in presence of methanol 21 and 22 are obtained. By photocleavage of the C(δ), O‐bond 9 is converted into b giving 14 . Photolysis of 14 yields 15 ( A + B ) and 16 . On 1 n,π*‐excitation (δ λ⩾ 347 nm) of 9 cleavage of the C(δ), O‐bond ( 9 → b ) seems to be the preferred reaction, whereas products of a are formed in traces, only.