Copper-catalyzed N-arylation of bis(indolyl)methanes: the first approach for the synthesis of unsymmetrical N-aryl bis(indolyl)methanes by C–N cross-coupling reaction

This investigation describes an efficient method for the synthesis of unsymmetrical N-aryl bis(indolyl)methanes by C–N cross-coupling reaction of unsubstituted bis(indolyl)methanes with aryl iodides in the presence of several Cu salts and CuFe$_{2}$O$_{4}$ as homogeneous and heterogeneous catalysts, respectively. Among these Cu containing catalysts, CuFe$_{2}$O$_{4}$ under ligand-free conditions showed the best activity and selectivity for mono N-arylation of bis(indolyl)methanes. Notably, CuFe$_{2}$O$_{4}$ catalyst was recovered and reused several times.