Photochemical reactions. 146th communication. Photochemistry of conjugated methano-epoxydienes: Participation of the neighboring cyclopropane ring in product formationvia carbonyl ylide and carbene intermediates
作者:Norbert Bischofberger、Bruno Frei、Oskar Jeger
DOI:10.1002/hlca.19850680610
日期:1985.9.25
On singlet excitation (λ = 254 nm, THF, pentane or hexane), the diastereoisomeric methano-epoxydienes (E)-6 and (E)-7 undergo interconversion and yield the products 8–11. The main process is the cleavage of the oxirane ring to the vinyl carbene intermediate e which undergoes addition to the adjacent double bond furnishing the cyclopropene 8. The alternative carbene intermediate f is evidenced by the
Photochemical reactions. 134th Communication. Photochemistry of 5,6-epoxy-5,6-dihydro-3,4-methano-?-ionone: Influence of a cyclopropane ring on the reactivity of an ylide intermediate
作者:Norbert Bischofberger、Bruno Frei、Oskar Jeger
DOI:10.1002/hlca.19840670117
日期:1984.2.1
On 1n,π*-excitation(λ > 347 nm), the diastereomeric methanoepoxyenones (E)-6 undergo isomerization via C,O-cleavage of the oxirane leading to diastereomeric photoproducts ((E)-5(E/Z)-13 and 14; (E)-6(E/Z)-16 and 17). On 1π,π*-excitation (λ = 254 nm) of either (E)-5) or (E-6 the photoproducts 9, 10 and 11 are formed. By laser flash photolysis (λ = 265 nm) the ylide intermediate 3 was detected, with