Zur vinylogen β-Spaltung von Enonen. UV.-Bestrahlung von 4-(3',7',7'-Trimethyl-2'-oxabicyclohept-3'-en-1'-yl)but-3-en-2-on

Article abstract of DOI:10.1002/hlca.19810640123

On ¹?,?^*-excitation (λ=254 nm) in acetonitrile (E/Z)-2 is converted into the isomers 4-9 and undergoes fragmentation yielding 10; in methanol (E/Z)-2 gives 7-10 and is transformed into 11 by incorporation of the solvent. On ¹?,?^*-excitation (λ>347 nm; benzene-d6) (E)-2 is isomerized into (Z)-2, which is converted into the isomers 3 and further 4 by further irradiation. ¹?,?^*-Excitation (λ=254 nm; acetonitrile) of 4 gives 6 and (E)-9, whereas UV.-irradiation (λ=254 nm; acetonitrile-d3) of 5 yields (E)-7 and 8. On ¹?,?^*-excitation (λ=254 nm; acetonitrile) of (E/Z)-12 the compounds (E)-14 and (E)-15 are obtained.