Electron-transfer photooxygenation. 8. dicyanoanthracene-sensitized photooxidation of ortho-dimethoxybenzene

Two cleavage products, $\text{cis,cis}$-dimethylmuconate ($\text{1}$) and $\text{trans,trans}$-dimethyl-muconate ($\text{2}$), are inefficiently produced in the 9,10-dicyanoanthracene (DCA) sensitized photooxidation of $\text{ortho}$-dimethoxybenzene ($\text{o}$-DMB) in polar solvents. An electron transfer mechanism is proposed in which superoxide ion (O^?₂0 combines with ortho-dimethoxybenzene to form a dioxetane (3), which cleaves to form ($\text{1}$). The initial products is $\text{1}$, which is rapidly converted to $\text{2}$ and other products under the conditions; $\text{no}$ cis-trans isomer is formed.