Photocatalytic oxygenation of olefins with oxygen. Isolation of 1,2-dioxetane and the photocatalytic O-O bond cleavage

Formation of 1,2-dioxetane of tetraphenylethylene (TPE) occurs via formation of the electron transfer state of 9-mesityl-10-methylacridinium ion (Acr⁺-Mes) under visible light irradiation, followed by electron transfer from TPE to the Mes{radical dot}⁺ moiety together with electron transfer from the Acr{radical dot} moiety to O₂, and the subsequent radical coupling between TPE{radical dot}⁺ and O₂{radical dot}^- to yield the corresponding 1,2-dioxetane. The dioxetane thus formed was isolated using column chromatography. Photooxygenation of stilbene derivatives is also efficiently catalyzed by Acr⁺-Mes, accompanied by efficient cis-trans isomerization, to afford the corresponding benzaldehydes via electron transfer from Acr{radical dot}-Mes{radical dot}⁺ to stilbene derivatives and oxygen.