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

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

Rhodium-Catalyzed Transannulation of <i>N</i>‑Sulfonyl-1,2,3-triazoles and Epoxides: Regioselective Synthesis of Substituted 3,4-Dihydro‑2<i>H</i>‑1,4-oxazines

Rhodium-catalyzed transannulation of 1,2,3-triazoles and ring-opening reactions of epoxides is described. A number of 3,4-dihydro-2<i>H</i>-1,4-oxazines are obtained in moderate yields probably involving generation of α-imino rhodium­(II) carbene species