Synthesis of Solubility-Enhanced 6,8-Diarylated Dibromodibenzo[a,j]phenazines via Pd-Catalyzed C–H Arylation and Skeletal Rearrangement

We report the synthesis of a new class of dibromodibenzo[a,j]phenazine (DBPHZ) derivatives bearing diaryl substituents at the 6,8-positions. These compounds were obtained through a combination of regioselective Pd-catalyzed C–H direct arylation and oxidative skeletal rearrangement of appropriately functionalized binaphthalenediamines. The compatibility of bromine substituents with the C–H arylation conditions was confirmed, enabling the incorporation of various aryl groups including diphenyl, tert-butylphenyl, and 3,5-dimethylphenyl moieties. Crystallographic analysis of a representative compound revealed that the diaryl units adopt a twisted geometry relative to the DBPHZ core. Solubility tests demonstrated that the introduction of diaryl substituents having alkyl groups significantly enhances solubility in common organic solvents such as toluene and chloroform, compared to unsubstituted DBPHZ. Owing to the retained dibromo functionality, the synthesized DBPHZs would serve as valuable synthetic building blocks for constructing π-extended functional organic materials.