Effects of solvent and base on the palladium-catalyzed amination: PdCl 2 (Ph 3 P) 2 /Ph 3 P-catalyzed selective arylation of primary anilines with aryl bromides

A readily accessible catalytic system, PdCl2(Ph3P)2/Ph3P, was developed for the selective arylation of primary anilines with aryl bromides. The strong influence of solvents and bases on the catalytic activity was observed. In refluxing o-xylene, triphenylphosphine shows high efficiency for Pd-catalyzed intermolecular amination reactions. By changing the bases, mono- and diarylation of primary amines could be selectively achieved in high yields. Moreover, the catalytic system showed good toleration for the steric hindrance of anilines. A series of N,N,N′,N′-tetraaryl-1,1′-biphenyl-4,4′-diamines, important intermediates of OLED hole transport materials, were synthesized facilely via coupling reactions between 4,4′-diaminobiphenyls and aryl bromides.