The phototransformations of several cycloadducts of 2, 3-diphenyl-2, 3-epoxy-l-indanone are reported. All these substrates exhibited singlet-state-mediated transformations leading to benzoxocinones, whereas in some cases, depending on the substituents present in the alkene moiety, triplet-state-mediated reactions leading to naphthalene derivatives have also been observed. Nanosecond laser pulse excitation gave transient absorptions tentatively ...