Negatively Charged π-Electronic Systems by Deprotonation of Hydroxy-Substituted Dipyrrolyldiketone Boron Complexes.

Boron complexes of meso-hydroxy-substituted dipyrrolyldiketones, as the precursors of negatively charged π-electronic systems, were synthesized via the oxidative introduction of an acetoxy unit at the meso position of dipyrrolyldiketones and subsequent hydrolysis. The anionic site formed upon deprotonation was moderately stabilized by hydrogen-bond-donating pyrrole NH, generating non-complexing anionic species.