Palladium-Catalyzed Suzuki-Miyaura Cross-Coupling of Various Aryl Halides Using ortho-Alkyl-Substituted Arylphosphanes and (ortho-Alkylphenyl)-alkylphosphanes under Microwave Heating.

Mono- and dinuclear palladium(II) chloride complexes of various ortho-alkyl-substituted aryl- and alkylphosphanes were prepared. Subsequently, these were characterized by 1H NMR and 31P{1H} NMR spectroscopy, X-ray crystallographic studies and mass spectroscopy. The palladium complexes were screened as potential catalysts for the microwave-assisted Suzuki–Miyaura coupling reaction of several aryl halides under aerobic conditions. A preliminary study showed that excellent results can be obtained even for electron-rich bromides and unactivated aryl chlorides with an optimized solvent, base and catalyst loading using specific phosphane ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)