| Abstract
| - Visible light irradiation of the absorption band of 9-mesityl-10-methylacridinium ion (Acr+−Mes)in an O2-saturated acetonitrile (MeCN) solution containing 9,10-dimethylanthracene results in formation ofoxygenation product, i.e., dimethylepidioxyanthracene (Me2An-O2). Anthracene and 9-methylanthracenealso undergo photocatalytic oxygenation with Acr+−Mes to afford the corresponding epidioxyanthracenesunder the photoirradiation. In the case of anthracene, the further photoirradiation results in formation ofanthraquinone as the final six-electron oxidation product, via 10-hydroxyanthrone, accompanied bygeneration of H2O2. When anthracene is replaced by olefins (tetraphenylethylene and tetramethylethylene),the photocatalytic oxygenation of olefins affords the corresponding dioxetane, in which the O−O bond iscleaved to yield the corresponding ketones. The photocatalytic oxygenation of anthracenes and olefins isinitiated by photoexcitation of Acr+−Mes, which results in formation of the electron-transfer state: Acr•−Mes•+, followed by electron transfer from anthracenes and olefins to the Mes•+ moiety together with electrontransfer from the Acr• moiety to O2. The resulting anthracene and olefin radical cations undergo the radicalcoupling reactions with O2•- to produce the epidioxyanthracene (An-O2) and dioxetane, respectively.
|
