par Zimmerman, Howard H.E.;Keese, Reinhart;Nasielski, Jacques 
;Swenton, John J.S.
Référence Journal of the American Chemical Society, 88, 21, page (4895-4904)
Publication Publié, 1966
;Swenton, John J.S.Référence Journal of the American Chemical Society, 88, 21, page (4895-4904)
Publication Publié, 1966
Article révisé par les pairs
| Résumé : | The photochemistry of 6,6-diphenylbicyclo[3.1.0]hex-3-en-2-one (2) was investigated. Evidence is reported for the structure of the photoacid previously described. This was shown to be 6,6-diphenyl-3,5-hexadienoic acid, the cis isomer of which was found to be initially formed. The phenolic product distribution was acid dependent with 2,3-diphenylphenol predominating under neutral and mildly acidic conditions but with a remarkable preference for 3,4-diphenylphenol resulting in more acidic medium. The reactions of the bicyclic ketone 2 were considerably less efficient than the rearrangement of 4,4-diphenylcyclohexadienone (1). Evidence was found in support of mesoionic zwitterion intermediates as precursors to the diphenylphenol products and suggesting that the phenolic products arose primarily from the triplet. The photoacid was found to come from both singlet and triplet processes. The excited states of bicyclic ketone 2 were shown not to revert to 4,4-diphenylcyclohexadienone. Additionally, the diphenylphenols obtained resulting from dienone 1 photolysis were shown to arise exclusively via the bicyclic ketone 2; no direct 4 → 3 phenyl migration in the dienone occurs. |
