Photoinduced Electron Transfer (PET) Cyclization and Photooxygenation of 2,6‐Diaryl‐1,6‐heptadienes and 2,7‐Diaryl‐1,7‐octadienes

The 2,6‐diaryl‐substituted 1,6‐heptadienes 3a – c and the 2,7‐diaryl‐substituted 1,7‐octadienes 4a – b were cleanly converted into the corresponding anellated cyclobutanes 5 and 6 , resp., when irradiated under photoelectron‐transfer conditions (9,10‐dicyanoanthracene in acetonitrile). Only for 4c did the rearranged compound 7c become the dominant photoproduct. Oxygen trapping experiments with formation of endoperoxides 8 , 9 were successful in the case of the electron‐rich substrates 3b , c and 4c .