28742-37-2Relevant academic research and scientific papers
Protonation of Tetraphenyl- and 2,3,4-Triphenylcyclopentadienone – An NMR and X-ray Crystallographic Study
Harrington, Laura E.,Britten, James F.,Casey, Michael,Grealis, John,Ortin, Yannick,Müller-Bunz, Helge,McGlinchey, Michael J.
, p. 3249 - 3255 (2017/06/21)
The protonation of 2,3,4,5-tetraphenylcyclopentadienone (tetracyclone) yields 6,11-diphenyl-5H-benzo[a]fluoren-5-one (17) and 2,3,4,5-tetraphenylcyclopent-2-en-1-one (18) as the major products. This contrasts with the pyrolysis of tetracyclone, which yields 5,6-diphenyl-11H-benzo[a]fluoren-11-one (22), a structural isomer of 17. Mechanisms are presented that rationalize these observations. The protonation of 4-hydroxy-2,3,4-triphenylcyclopent-2-en-1-none, the precursor to 2,3,4-triphenylcyclopentadienone, generates 2-(2′-oxo-3′,4′,5′-triphenylcyclopent-3′-enyl)-3,4,5-triphenylcyclopenta-2,4-dienone (30), which has been unequivocally characterized by X-ray crystallography. The establishment of the conformation of molecule 30 in the solid state, which correlates with the conformation in solution, provides a rationale for the subsequent formation of the tetrahydro-pentaphenyl-as-indacene-3,4-dione (32) upon further protonation.
