ATTEMPTED SYNTHESIS OF BOWL-SHAPED POLYCYCLIC AROMATIC-HYDROCARBONS VIA OXIDATIVE ELECTROCYCLIZATION - PRODUCTS FROM THE DICATIONS OF DIBENZO[GP]CHRYSENE, TETRABENZO[5.5]FULVALENE, AND DIPHENYLMETHYLIDENEFLUORENE

Synthesis of diindeno[1,2,3,4-defg: 1',2',3',4'-mnop]chrysene (1), a p ortion of the C-60 surface, was attempted through oxidative cyclizatio n of tetrabenzo[5.5]fulvalene (2), dibenzo[gp]chrysene (3), and diphen ylmethylidenefluorene (4) by SbF5/SO2ClF. Compounds 2 and 3 were oxidi zed to dications which then underwent a single cyclization to give pre cursors to 1. Compound 4 underwent two oxidative cyclizations to give a precursor to 1. AM1 calculations of the possible products from cycli zation were consistent with preferential formation of the cyclized pro duct with the lower Delta H-f. Oxidative cyclization may offer a one-p ot synthetic alternative for the preparation of unusual polycyclic aro matic hydrocarbons.