Synthesis of Proline-Based N-Heterocyclic Carbene Building Blocks and Their Applications

The synthesis of novel proline-based N-heterocyclic carbene ligands has been accomplished. These types of imidazolium salts can be used as building blocks for the synthesis of more sophisticated N-heterocyclic carbene precursors. The proline amino acids are shown to be compatible with peptide synthetic methods by incorporation into tripeptides. The approaches to a variety of bidentate ligand precursors was reported. A number of the ligands synthesized were bound to rhodium through transmetallation of a silver-NHC complex.