Palladium complexes with cinnamyl and ionizable N-heterocyclic carbene ligands in the catalysis of the Suzuki—Miyaura reaction at room temperature

The complexes [Pd(NHC)(cin)Cl] containing nitron-type N-heterocyclic carbene (NHC) ligands were synthesized. These ligands can acquire an anionic character due to the deprotonation of the NH-acidic arylamino group. The catalytic activity of the new complexes in the Suzuki—Miyaura reaction was evaluated. The η3-coordinated cinnamyl (cin) ligand, which is present in the complexes and acts as a reducing agent of Pd(ii) to Pd(0) in the presence of bases, promotes the rapid activation of the catalytic system. The complex with the 2,4-bis[2,6-diisopropylphenyl]-5-{[2,6-diisopropylphenyl]amino}-2,4-dihydro-3H-1,2,4-triazol-3-ylidene ligand showed a high efficiency in the catalysis of the cross-coupling of arylboronic acids with deactivated aryl chlorides and benzyl chlorides at 25 °C.