Discovery of Deep-Seated Skeletal Rearrangements in the Photocyclizations of Some <i>tert</i>-Butyl-Substituted 1,2-Diarylethylenes

The in-solution oxidative photocyclization of stilbenes to phenanthrenes is a well-known and synthetically valuable reaction. We report here our discovery that the oxidative photocyclization of several <i>tert-</i>butyl-substituted 1-styrylphenanthrenes resulted not only in the expected formation of <i>tert-</i>butyl-substituted picenes but also in the previously unknown rearrangement leading to the formation of <i>tert-</i>butyl-substituted pentahelicenes

Phenyl Groups versus <i>tert</i>-Butyl Groups as Solubilizing Substituents for Some [5]Phenacenes and [7]Phenacenes

In recent years, we have used the photocyclizations of diarylethylenes to synthesize a number of [<i>n</i>]­phenacenes in the hope that they might be useful as the bridging groups for electron transfer processes in donor–bridge–acceptor molecules. Because [<i>n</i>]­phenacenes with <i>n</i> > 5 are very insoluble, their synthesis and characterization has required the attachment of solubilizing substituents such as <i>tert</i>-butyl. The studies of Pascal and co-workers of some large polynuclear aromatic compounds having multiple phenyl substituents prompted us to explore the use of phenyls as alternative solubilizing groups for [<i>n</i>]­phenacenes. Although phenyl groups turned out to provide significantly less solubilization than <i>tert</i>-butyl groups in these compounds, we found some interesting structural comparisons of the phenyl-substituted and <i>tert</i>-butyl-substituted [<i>n</i>]­phenacenes

Phenyl Groups versus <i>tert</i>-Butyl Groups as Solubilizing Substituents for Some [5]Phenacenes and [7]Phenacenes

In recent years, we have used the photocyclizations of diarylethylenes to synthesize a number of [<i>n</i>]­phenacenes in the hope that they might be useful as the bridging groups for electron transfer processes in donor–bridge–acceptor molecules. Because [<i>n</i>]­phenacenes with <i>n</i> > 5 are very insoluble, their synthesis and characterization has required the attachment of solubilizing substituents such as <i>tert</i>-butyl. The studies of Pascal and co-workers of some large polynuclear aromatic compounds having multiple phenyl substituents prompted us to explore the use of phenyls as alternative solubilizing groups for [<i>n</i>]­phenacenes. Although phenyl groups turned out to provide significantly less solubilization than <i>tert</i>-butyl groups in these compounds, we found some interesting structural comparisons of the phenyl-substituted and <i>tert</i>-butyl-substituted [<i>n</i>]­phenacenes