Synthesis of Bis(phenanthropyrroles) via a Tandem Scholl Oxidation

An electron-rich 3,4-diarylpyrrole is shown to undergo a tandem inter- and intramolecular Scholl oxidation, providing access to bis­(phenanthropyrroles), a new class of bipyrrole derivatives with extended π conjugation. Intermolecular coupling of two pyrrole molecues is found to be the initial step of this reaction. Bis­(phenanthropyrroles) are characterized by restricted rotation around the α–α bond and exhibit strong blue fluorescence and large Stokes shifts.