Acid-catalyzed dehydration of 4-hydroxy-2, 3, 4-triphenyl-2-cyclopentenone (1) affords a mixture of dimers and a dehydrodimer of 2, 3, 4-triphenylcyclopentadienone (2). The structures of three of these dimers have been established as 2, 3-dihydro-3, 3′, 4, 4′, 5, 5′-hexaphenyl-2, 2′-bis (cyclopentadienone)(3),(E)-3, 3′, 4, 4′, 5, 5′-hexaphenyl [bi-3- cyclopentenylidene]-2, 2′-dione (5), and 3a, 3b, 6a, 10b-tetrahydro-1, 2, 5, 6, 6a- ...
