Novel photoreaction of 4-tribromomethyl-4-methyl-2,5-cyclohexadienone with amine

Photoreactions of 4-(Tribromomethyl)-4-methyl-2,5-cyclohexadienone and Its Derivatives with Amines: Radical Cyclization and Ring Expansion Reactions Promoted through Photoinduced Electron Transfer Processes

“…Therefore, the presence of a carbonyl group and a carbon−halogen bond in the same molecule could irreversibly reduce the distant carbon−halogen bond through intramolecular electron transfer upon generation of a ketyl radical . Since such a process should finally generate a carbon radical, the PET reaction of the substrates possessing both an α,β-unsaturated enone structure and a carbon−halogen bond would lead to the carbon−carbon bond formation at the β-position of enone (formal intramolecular 1,4-radical addition). , On the other hand, SET to 4,4-disubstituted-2,5-cyclohexadienones in some cases leads to the facile cleavage of carbon−carbon as well as carbon−heteroatom bonds at the C 4 position, thus gaining resonance stabilization through aromatization, which yields substituted phenols as isolable products. , Interestingly, no information was available about the behavior of 4-(trihalomethyl)-4-methyl-2,5-cyclohexadienones under PET conditions before our study, although the photochemistry of 2,5-cyclohexadienones has been extensively studied earlier by Schuster and co-workers .…”