The Thermal Isomerization of Dicyclopentaheptalene (Azupyrene) to Pyrene

Article abstract of DOI:10.1021/jo00002a014

<2a,11-13C2>Dicyclopentaheptalene (azupyrene) has been synthesized from <1,2-13C2>cyclopentanone which, in turn, was prepared from 13C-labeled cyanide and 13C-labeled iodomethane.Thermal isomerization of the labeled azupyrene gave <3a,11-13C2>pyrene.The only proposed mechanism consistent with this result are the radical-initiated methylene walk and that involving a peripheral bicyclobutane intermediate.These mechanisms are also in agreement with previous results from the isomerization of 1-methylazupyrene except for an additional minor product in the latter experiment.Evidence for the automerization of pyrene under the thermal isomerization conditions has been obtained.