Benzimidazole Bearing Pd-Peppsi Complexes Catalyzed Direct C2-Arylation/Heteroarylation Ofn-Substituted Benzimidazoles

A convenient and highly efficient palladium-catalyzed direct C2-arylation/heteroarylation ofN-substituted benzimidazole derivatives such asN-benzyl/3-chlorobenzyl/2,4,6-trimethylbenzyl/2,4,6-triisopropylbenzyl/aryl benzimidazoles with various aryl/heteroaryl bromides in the presence of Pd-PEPPSI (palladium-pyridine enhanced pre-catalyst preparation stabilization and initiation) complexes is reported. In order to that we have prepared a series of different symmetrical and unsymmetricalN,N '-diaralkyl benzimidazole-bearing Pd-PEPPSI complexes. Among all of the the prepared complexes, Pd-PEPPSI-3effectively tuned the reaction at a relatively higher rate under mild reaction conditions in an ethanol-water system. In addition, the catalytic process avoids the use of external ligand and additives. Further the reactivity was compared with commercially available copper-N-heterocyclic carbene catalyst, but the reaction was less successful. With the optimized reaction conditions, a wide range of 2-aryl/heteroaryl-N-substituted benzimidazoles were synthesized in good to excellent yields via Csp(2)-H/Csp(2)-X biaryl cross-coupling.