Attempted Synthesis of Bowl-Shaped Polycyclic Aromatic Hydrocarbons via Oxidative Electrocyclization. Products from the Dications of Dibenzo [g,p] chrysene,Tetrabenzo[5.5]fulvalene,and Diphenylmethylidenefluorene

Synthesis of diindeno[1,2,3,4-defg: 1′,2′,3′,4′-mnop]chrysene (1), a portion of the C₆₀ surface, was attempted through oxidative cyclization of tetrabenzo[5.5]fulvalene (2), dibenzo[gp]chrysene (3), and diphenylmethylidenefluorene (4) by SbF₅/SO₂CIF. Compounds 2 and 3 were oxidized to dications which then underwent a single cyclization to give precursors to 1. Compound 4 underwent two oxidative cyclizations to give a precursor to 1. AM1 calculations of the possible products from cyclization were consistent with preferential formation of the cyclized product with the lower ΔHf. Oxidative cyclization may offer a one-pot synthetic alternative for the preparation of unusual polycyclic aromatic hydrocarbons.