Dicyclohexylphosphino Cyrhetrene: Synthesis, Characterization And Catalytic Evaluation Toward Suzuki-Miyaura Cross-Coupling Reaction Of Aryl Bromides And Chlorides

Reaction of cyrhetrene ((η5-C5H5)Re(CO)3) with n-butyllithium (1.0 equiv, − 78 °C) and then ClPCy2 (Cy = cyclohexyl) gives the new cyrhetrenyl-phosphino ligand (η5-C5H4PCy2)Re(CO)3 which was isolated as a pure sample in 86% yield and characterized by standard spectroscopic techniques (FT-IR, 1H, 13C and 31P NMR), MS, X-ray diffraction and Elemental Analysis). This rhenium containing cyrhetrenyl phosphine combined with Pd(OAc)2 (2:1 mol ratio) resulted an efficient catalytic system for Suzuki couplings of aryl bromides and aryl chlorides with phenylboronic acid. The catalyst exhibits a high activity, with conversions of 100% after 20 min.