Synthesis, X-ray structures, and catalytic activities of (κ2-C,N)-palladacycles bearing imidazol-2-ylidenes

Quaternisation of methylimidazole (1) by methyl substituted benzyl bromides afforded imidazolium salts (2) which were converted to (κ2-C,N)-palladacycles bearing imidazol-2-ylidenes 6 or 7, by either in situ deprotonation or via Ag–NHC intermediate (3), using the bridged palladacycles 4 or 5, respectively. The palladacycles 6 and 7 were characterized by elemental analysis; NMR spectroscopy and the molecular structure of 6c and 7c were determined by X-ray crystallography. The complexes 6 and 7 display high activity in Suzuki–Miyaura coupling of a range of aryl bromides.

Graphical abstractQuaternisation of methylimidazole by methyl substituted benzyl bromides afforded imidazolium salts which were converted to (κ2-C,N)-palladacycles bearing imidazol-2-ylidenes, by either in situ deprotonation or via Ag–NHC intermediate, using the bridged palladacycles.Figure optionsDownload full-size imageDownload as PowerPoint slide