Highly Efficient Direct arylation of Imidazo[1,2-a]pyridine Derivatives by Pd-PEPPSIComplexes

On the basis of development highly efficient protocol for Pd-catalyzed direct C-H cross-coupling reactions, bulky bis(imino)acenaphthene(BIAN)-supported Pd-PEPPSI complexes was applied in the arylation of imidazo[1,2-a]pyridine. The effect of N-moieties on NHCs was evaluated, and the cross coupling reaction conditions were screened. It revealed that the bulky Pd-PEPPSI complexe of C2 could be successfully employedin the coupling of aryl bromides at a lowpalladium loading of 0.1～0.05 mol %.