Photooxygenation od 1,ω-Bis(diarylethenyl)alkanes via Photoinduced Electron-Transfer: Formation of 1,4-Radical Cations and Its Trapping by Molecular Dioxygen

Article abstract of DOI:10.1021/jo00103a025

The 9,10-dicyanoanthracene (DCA)-sensitized photooxygenation of 1,ω-bis(diarylethenyl)alkanes (Ar2C=CH(CH2)nCH=Ar2) was studied.The photooxygenation of the alkadienes in acetonitrile afforded bicyclic peroxides when Ar = 4-CH3OC6H4, n = 3 and 4.When Ar = 4-CH3OC6H4, n = 2, 5, 8 or Ar = C6H5, n = 3, the photooxygenation did not afford bicyclic peroxides, but gave diaryl ketones.Laser flash photolysis studies indicated that the photooxygenation is initiated by a one-electron transfer from the alkadienes to ¹DCA^* and proceeds via 1,4-radical cations that are generated by an intramolecular cyclization between an ethenyl moiety and a radical cation of another ethenyl moiety.