Photooxygenation of an enol ether: Synthesis of exo- and endo-3,4-dioxa-2,5-dimethoxy-7,8-benzo[4.2.2.02,5] deca-7,9-diene and its chemical transformations

Article abstract of DOI:10.1016/S0040-4020(01)80167-8

The reaction of singlet oxygen with 2 afforded two isomeric dioxetanes 3 and 4 which were decomposed upon heating to the expected dihydronaphthalene derivative 5. Photooxygenation of 2 in the presence of thiourea resulted in the formation of diketone 8 and ketal 7 ; the later presumably derived from incorporation of the solvent molecule.