Several silver(I) complexes with chiral amino-N-heterocyclic carbene (NHC) ligands, which are not diastereomerically pure, were prepared and used to generate in situ chelating NHC-amino palladiumt(II) complexes. The potential of these palladium(II) complexes in asymmetric catalysis was evaluated in the allylic alkylation reaction. The influence of the structure and of the diastereomeric purity of the ligands on enantio selectivity, as well as the role of the silver salts, were studied. Enantiomeric excesses of up to 80% were obtained with the best ligand. (c) 2007 Elsevier Ltd. All rights reserved.
Synthesis of chiral imino- and amino-imidazolium salts and of chelating amino-N-heterocyclic carbene palladium(II) complexes
by X-ray diffraction. Chelating amino-N-heterocyclic carbene dichloro palladium(II) complexes were obtained in two steps via formation of the corresponding silver(I) complexes and reaction of these latters with bis(acetonitrile)dichloropalladium. Crystal structure details of a cis-dichloro amino-imidazol-2-ylidene palladiumcomplex are presented and confirmed the formation of a six-membered Pd-metallocycle