Palladium Complexes with Tetrahydropyrimidin-2-ylidene Ligands: Catalytic Activity for the Direct Arylation of Furan, Thiophene, and Thiazole Derivatives

The synthesis and characterization of novel 1,3-benzyl-3,4,5,6-tetrahydropyrimidin-2-ylidene-based N-heterocyclic carbene palladium­(II) complexes (1a–d) were described. The crystal structure of trans-dichlorobis­[1,3-bis­(4-methylbenzyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene]­palladium­(II) was presented. Pd­(II) complexes 1a–d were tested as catalysts in the direct C5 or C2 arylation of furans, thiophenes, and thiazoles, with various aryl bromides at 150 °C for 1 h. These complexes exhibited moderate to high catalytic activities under the given conditions.