Preparation and Properties of endo,endo-7,8-Diphenylbicycloocta-2,4-diene

Article abstract of DOI:10.1021/jo00148a008

endo,endo-7,8-Diphenylbicyclo<4.1.1>octa-2,4-diene (10) has been prepared in ten steps from ε-truxillic acid.If the pendant phenyl substituents in this hydrocarbon could adopt conformations where they become approximately coplanar with the diene segment, the possibility for substantive electronic delocalization through the cyclobutane relay orbitals exists.Three-dimensional X-ray crystal structure analysis of 10 reveals that while the unsaturated four-carbon bridge is essentially planar, one of the aryl rings is twisted 20 deg out of plane because proximity factors prohibit parallel stacking.Additionally, photoelectron spectroscopic analysis of 10 and several model compounds (17, 18, and 23) shed no light on the question of through-bond interaction because of high-level interference arising from electron promotion out of the benzene rings.Nonetheless, the chemical reactivity of 10 is very high, it being very prone to thermolysis and photolysis.Interestingly, the reactions which occur under these conditions find no parallel with the behavior of lesser substituted prototype structures.