CuCl-Catalyzed Hydroxylation of N-Heteroarylcarbazole Bromide: Approach for the Preparation of N-Heteroarylcarbazolyl Phenols and Its Application in the Synthesis of Phosphorescent Emitters

An efficient and practical CuCl-catalyzed hydroxylation of N-heteroarylcarbazole bromide for the preparation of N-heteroarylcarbazolyl phenols with a broad functional group scope and yield up to 98% was developed. It was found that both the ligand and base played critical roles in the functional group transformation and that different products could be generated by changing the base for some substrates. t-BuONa was demonstrated to be a better base for the catalytic system to avoid the formation of the ether byproduct. In addition, this approach was suitable for large-scale preparation and was successfully applied in the gram-scale synthesis of phosphorescent emitters PtNON and PdNON, demonstrating its practicability in organic synthesis methodology and materials science. Furthermore, the X-ray crystal diffraction, DFT calculations, and photophysical properties were also investigated for the metal complexes.