Synthesis of novel pillar[5]arene-based N-heterocyclic carbene ligands for Pd-catalysed Heck reactions

Pillar[5]arene-based 1-benzylimidazole and 1-(9-anthracenylmethyl)imidazole salts were prepared for the first time as novel class supramolecular NHC ligands. These ligands, together with PdCl2(CH3CN)(2), were used as catalysts in the Heck coupling reactions of styrene and aryl halide derivatives. The 1-(9-anthracenylmethyl)imidazole salt exhibited better catalytic activity than the 1-benzylimidazole salt, owing to the steric bulk of the ligand. The novel pillar[5]arene-based imidazolium salt is a promising supramolecular skeleton for the construction of highly active catalysts. (C) 2016 Elsevier Ltd. All rights reserved.