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

Quaternisation of methylimidazole (1) by methyl substituted benzyl bromides afforded imidazolium salts (2) which were converted to (kappa(2)-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. (C) 2009 Elsevier B.V. All rights reserved.