Synthesis, characterization and the Suzuki–Miyaura coupling reactions of N-heterocyclic carbene–Pd(II)–pyridine (PEPPSI) complexes

• New N-heterocyclic carben ligands precursors, (1a–f), have been synthesized.
• Novel palladium- NHC-pyridine complexes, (2a–f), have been synthesized.
• With this catalyse system unactivated aryl chlorides arylated under mild reaction condition.

N-heterocyclic carbenes (NHCs) are a significant and powerful class of ligands for transition metals. A new series of air and moisture-stable NHC–PdCl2-pyridine complexes, (2a–f), have been described. With the development of a more efficient catalytic system for the cross-coupling of aryl halides in mind, the catalytic performance of the NHC–PdCl2-pyridine complexes for Suzuki cross-coupling under mild conditions in aqueous N,N-dimethylformamide (DMF) was investigated. Electron-rich and electron-poor aryl chlorides were facilely coupled with boronic acids by NHC–PdCl2-pyridine complexes.

Highly active, easy to producible and environmentally friendly N-heterocyclic carbene precursors and their palladium-II pyridine complexes were synthesized and catalytic activities of Pd-NHC-pyridine complexes for Suzuki cross-coupling in aqueous media were investigated. The catalysis system is simple and efficient toward various pre-activated aryl chlorides.Figure optionsDownload as PowerPoint slide