<i>N</i>‑Heterocyclic Carbene-Stabilized Palladium Complexes as Organometallic Catalysts for Bioorthogonal Cross-Coupling Reactions

Abstract

A small library of water-soluble <i>N</i>-heterocyclic carbene (NHC)-stabilized palladium complexes was prepared and applied for cross-couplings of biomolecules under mild conditions in water. Pd–NHC complexes bearing hydrophilic groups were demonstrated to be efficient catalysts for the Suzuki–Miyaura coupling of various unnatural amino acids and proteins bearing <i>p</i>-iodophenyl functional groups. We further utilized this catalytic system for the rapid bioorthogonal labeling of proteins on the surfaces of mammalian cells. These results demonstrated that NHC-stabilized metal complexes have potential utility in cellular systems