Irradiation in the nπ* absorption band of the α,β-unsaturated γ,δ-epoxyketone 5 in ethanol at −65° exclusively afforded the rearranged ene-dione 13, whereas at + 24° under otherwise unchanged reaction conditions or upon triplet sensitization with Michler's ketone and with acetophenone at + 24° essentially identical mixtures of 13 (major product), 14, and 15 were obtained. Selective ππ* excitation of
照射在Ñ π*的α,β不饱和γ,δ-环氧酮的吸收带5在
乙醇中在-65℃专门提供的重排的烯二酮13否则不变的反应条件下或在三线态敏化,而在+ 24°用Michler 's酮和
苯乙酮在+ 24°时,得到的13种(主要产物),14和15的混合物基本相同。在-78°和+ 24°处5的选择性ππ*激发导致相似的产物模式。9β,10β-表观环氧酮7在+ 24°和n下选择性异构化为14和15 π*或ππ*激发。