Synthesis, characterization and X-ray structures of N-heterocyclic carbene palladium complexes based on calix[4]arenes: highly efficient catalysts towards Suzuki-Miyaura cross-coupling reactions

摘要

A new series of calix[4]arene supported N-heterocyclic carbene palladium complexes were developed and fully characterized. A mono-substituted calix[4]arene was prepared through conventional procedures, following with the attachment of imidazolyl derivative groups to compose the precursors of novel NHCs ligands. Undergoing the alkylation with n-butylbromide and corresponding metallation with palladium and pyridine, original complexes were obtained. After a full characterization in solution and solid state, the evaluation of catalytic activity was taken out in Suzuki-Miyaura cross-coupling reactions, which revealed good performances.