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New N,N′-substituted imidazolium salts and their corresponding dibromidopyridine-palladium(II) complexes were successfully synthesized and characterized. Reactions of palladium bromide with the newly synthesized N,N′-substituted imidazolium bromides (2a and 2b) in pyridine afforded the corresponding new N-heterocyclic carbene pyridine palladium(II) complexes (3a and 3b) in high yields. Their single-crystal X-ray structures show a distorted square planar geometry with the carbene and pyridine ligands in trans position. Both complexes show a high catalytic activity in carbonylative Sonogashira coupling reactions of aryl iodides and aryl diiodides with arylalkynes, alkylalkynes and dialkynes.

Suzuki-Miyaura reactions of 2,4,5,6-tetrachloropyrimidine allow a convenient synthesis of mono-, di-, tri-and tetraarylpyrimidines which are not readily available by other methods. All reactions proceed with excellent site-selectivity.

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