Chiral Oxazoline/Imidazoline-2-ylidene Complexes

Abstract

N-Heterocyclic “carbene” ligands derived from imidazole are alternatives for the well-established phosphines in organometallic catalysis. In contrast to phosphines, they do not easily dissociate from transition metals (e.g., palladium, rhodium) so they seem suited for chiral modifications. This publication reports on the synthesis and coordination chemistry of novel bidentate ligands with both imidazoline-2-ylidene and oxazoline moieties. The synthesis follows straightforward routes, using N-functionalized imidazolium salts and 2-amino alcohols. The crystal structures of palladium and rhodium complexes are presented. With rhodium, the ligands show a chelating coordination mode.