Electron-transfer photochemistry of endoperoxides

Derivatives of 1,2-dioxacyclohex-4-ene and 2,3-dioxabicyclo[2.2.2]oct-5-ene (endoperoxides, EPs) form EDA complexes with tetracyanoethylene (TCNE). The phenyl-substituted EPs 3a, 4a, 4b, and 6 undergo electron-transfer-induced reactions when the EDA complexes are irradiated. Two types of reactions are observed depending on the ring system. Monocyclic EPs (3a, 4a, and 4b) afford furan derivatives, possibly through the Criegee-type rearrangement, and dehydration, whereas the bicyclic EP 6 undergoes cycloreversion through the C–O cleavage.