Benzo‐fused Tri[8]annulenes as Molecular Models of Cubic Graphite

Cyclotrimerization of 9,10-dibromo-9,10-dihydrodibenzo[3,4:7,8]cycloocta[1,2-l]phenanthrene with potassium tert-butoxide in the presence a transition-metal catalyst afforded two polycyclic aromatic hydrocarbon stereoisomers consisting three cyclooctatetraene (COT) moieties connected via central benzene ring. Both isomeric tri[8]annulenes were obtained selectively through choice catalyst: The α,α,α-form (Ru catalyst) displayed threefold symmetrywith COT subunits forming side walls (chiral) molecular cup. In thermodynamically more stable α,α,β-isomer (Pd catalyst), one boat-shaped COTs was flipped over and faced opposite hemisphere respect to ring as evidenced by crystal structure analysis. title compounds are small segments “cubic graphite”, an elusive carbon allotrope.