N-Heterocyclic carbenes: Part 26. N-Heterocyclic carbene complexes of palladium(0): synthesis and application in the Suzuki cross-coupling reaction

Palladium(0) complexes of N-heterocyclic carbenes (NHC) are easily obtained starting from the free carbene and bis(tri-ortho-tolylphosphine)palladium(0) by ligand exchange. The complexes [(R)]2Pd of various 1,3-disubstituted imidazolin-2-ylidenes have been prepared by this method (R=mesityl, t-Bu, i-Pr, cyclohexyl). The activities of these complexes as catalysts for the activation of chloroarenes in the Suzuki cross-coupling reaction were evaluated. Turnover frequencies up to 552 (mol product×mol Pd−1×h−1] were achieved without specific optimization of the system.