关键词: 环钯化二茂铁亚胺, 三苯基膦, Suzuki 偶联, 芳基溴, 苯基硼酸

Abstract: Biaryls are important fine chemicals and constitute ubiquitous fragments of numerous biologically active natural products, pharmaceuticals as well as functionalized materials. As one of the most powerful methods for the formation of biaryls, palladiumcatalyzed Suzuki coupling reaction of aryl halides with aryl boronic acids has attracted much research interest. In this article, three novel cyclopalladated ferrocenylimine triphenylphosphine complexes 2-4 were easily synthesized and characterized by elemental analysis(or HRMS), IR, ¹H NMR, ³¹P NMR and X-ray single crystal diffraction. Compounds 2-4 were stable to air and moisture both in the solid state and in solution. These complexes were successfully used as catalysts in the Suzuki coupling of aryl bromides and heteroaryl bromides with phenylboronic acid. Using molar fraction 0.01% of catalyst 3 in the presence of 2 equiv. of K₃PO₄ as base in toluene at 110 ℃ for 5-15 h, a variety of aryl bromides with different electronic and steric effect and some heteroaryl bromides could be coupled with phenylboronic acid to afford the coupled products with moderate or excellent yields. Compared with phenyl bromide, the catalyst loading could be lowered to 0.001% providing the coupled products in good yields in the case of aryl bromides bearing electron-withdrawing groups. The reaction needed more time to get higher yields in the case of aryl bromides bearing electron-donating group or sterically hindered bromides.

Key words: Cyclopalladated ferrocenylimines, Triphenylphosphine, Suzuki coupling, Aryl bromides, Phenylboronic acid