Synthesis of Ester- and Phosphonate-Functionalized AuI -Imidazolylidene Chlorides through the Isonitrile Route

Abstract

Starting from DMSAuCl, isonitriles and functionalized propargylammonium salts in the presence of simple trimethylamine as auxiliary base, unsymmetrically substituted ester- and phosphonate-functionalized Au^I -imidazolylidene complexes were synthesized in an easy-to-use modular one-pot template synthesis. In the course of the reaction, after the initial nucleophilic addition of the amine to the gold(I)-activated isonitrile, a Michael addition closes the N-heterocyclic carbene (NHC) ring. Then the remaining double bond migrates into the NHC ring, evidently a more stable position than the initial exocyclic double bond. These functional groups attached to the back bone of the NHC ligands represent ideal handles for a further modification of the system, for example an attachment to larger assemblies or heterogenization by an attachment to surfaces are conceivable.

Keywords: N-heterocyclic carbene ligands; gold; isonitriles; template synthesis.