Dicyclohexylphosphino cyrhetrene: Synthesis, characterization and catalytic evaluation toward Suzuki-Miyaura cross-coupling reaction of aryl bromides and chlorides

Abstract

Reaction of cyrhetrene ((η5-C5H5)Re(CO)3) with n-butyllithium (1.0equiv, −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 (2:1mol 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 20min.