Synthesis of Triphenylene Derivatives by Rhodium-Catalyzed [2 + 2 + 2] Cycloaddition: Application to the Synthesis of Highly Fluorescent Triphenylene-Based Long Ladder Molecules

The convenient synthesis of substituted tri­phenyl­enes and aza­tri­phenyl­enes has been achieved by the cationic rhodium­(I)/H8-BINAP or BINAP complex-catalyzed [2 + 2 + 2] cycloaddition under mild conditions. Photophysical properties of representative tri­phenyl­enes and aza­tri­phenyl­enes were examined, which revealed that aza­tri­phenyl­enes showed higher fluorescence quantum yields than tri­phenyl­enes. This method was successfully applied to the synthesis of highly fluorescent triphenylene-based long ladder molecules.