PHOTO-OXYGENATION OF 1,2-DIARYLCYCLOPROPANES VIA ELECTRON TRANSFER

Article abstract of DOI:10.1016/S0040-4020(01)96594-9

The photo-oxygenation of 1,2-diarylcyclopropanes bearing electron-donating substituents in the presence of 9,10-dicyanoanthracene (DCA) in acetonitrile affords trans- and cis-3,5-diaryl-1,2-dioxolanes in excellent yields.The DCA-sensitized photo-oxygenation of less electron-rich 1,2-diarylcyclopropanes gives various oxidation products in low yields.These photoreactions are greatly accelerated by the addition of certain aromatic hydrocarbons and metal salts, and are completely quenched by the addition of triethylamine and 1,4-diazabicyclo<2.2.2>octane.No photo-oxygenation takes place in non-polar solvents.The electron transfer mechanism is proposed for the photo-oxygenations, in which the cation radicals of 1,2-diarylcyclopropanes are involved as chain carriers.