Photochemische Reaktionen. 95. Mitteilung. Zur Photochemie konjugierter Epoxy-enone: Die UV.-Bestrahlung von 9-Isopropyl-6-methyl-9, 10-epoxybicyclo [4.4.0] dec-1-en-3-on

The Photochemistry of Conjugated Epoxy-enones: Photolysis of 9-Isopropyl-6-methyl-9,10-epoxybicyclo 4.4.0]dec-l-en-3-on The title compound 1 undergoes on π, π*-excitation vinylogous β-cleavage of the C(γ), O-bond and isomerizes to the unsaturated 1, 5-diketone 8 (58%) and the tricyclic diketone 9 (14%). On n, π*-excitation, however, 1 undergoes only desoxygenation to the dienone 7 (ca. 15%) besides polymerization. UV.-irradiation of 1 (λ ≥ 347 nm) in the presence of tributyl-stannane gives 7 in 85% yield; in the presence of tributylstannane-d₁ 1 yields 13 , the deuterated analogon of 7 (85% yield; d₁ ca. 50%); 7 has been proven to be stable on π, π* - as well as on n, π*-excitation.