Palladium-Catalyzed Double N-Arylation to Access Unsymmetric N,N′-Bicarbazole Scaffolds

Herein, the palladium-catalyzed double C-N coupling of 9H-carbazol-9-amines and 2,2'-dibromo-1,1'-biphenyl is reported. This protocol offers access to N,N'-bicarbazole scaffolds, which have frequently been used as linkers in the construction of functional covalent organic frameworks (COFs). A variety of substituted N,N'-bicarbazoles were synthesized in moderate to high yields based on this chemistry, and the potential application of this method was showcased by the synthesis of COF monomers like tetrabromide 4 and tetraalkynylate 5.