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.