An efficient, mild and selective Ullmann-type N-arylation of indoles catalysed by Pd immobilized on amidoxime-functionalized mesoporous SBA-15 as heterogeneous and recyclable nanocatalyst

A wide range of N-arylated indoles were selectively synthesized through intermolecular C(aryl)N bond formation from the corresponding aryl iodides and indoles through Ullmann-type coupling reactions in the presence of a catalytic amount of Pd immobilized on amidoxime-functionalized mesoporous SBA-15 (SBA-15/AO/Pd(0)) under mild reaction conditions. These cross-coupled products were obtained in excellent yields under mild conditions at extremely low palladium loading (ca 0.3mol%), and the heterogeneous catalyst can be readily recovered by simple filtration and reused seven times with loss in its activity. Copyright (c) 2015 John Wiley & Sons, Ltd.