Imidazolium salicylaldimine frameworks for the preparation of tridentate N-heterocyclic carbene ligands

Abstract

Sterically hindered salicylaldimine functionalized imidazolium salts 2 have been prepared. The structures of the synthesized compounds were determined by spectroscopic techniques. The reaction of these salts containing arylmethyl-N chain (aryl: phenyl (2a), 2,4,6-trimethylphenyl (2b), 2,3,4,5,6-pentamethylphenyl (2c)) with Pd(OAc)(2) in boiling toluene a. orded Pd(II) complexes 3 in high yields. The X-ray structure of 1-[3-(3,5-di-tert-butyl-2-oxophenyl) propyliminato]-3-(2,4,6-trimethylbenzyl) imidazol-2-ylidenebromopalladium( II) (3b) has been determined. The Suzuki-Miyaura reaction was used to investigate their activity as catalysts either prepared in situ or from well-defined complexes. They are efficient when activated arylbromides are used as substrates. (C) 2008 Elsevier B.V. All rights reserved.