Synthesis and characterization of orthopalladated complexes of 4-chloro benzoylmethylene triphenylphosphorane and their application in Suzuki cross-coupling

Abstract

Orthopalladated binuclear complexes (1) have been prepared by refluxing a mixture of the phosphorus ylide (ClBPPY) with Pd(OAc)₂ in CH₂Cl₂. Complex 1 reacts with ligands (L) to give (L = PPh₃ (2), Me₃Py (3)). Cyclopalladated complexes are highly efficient catalysts for the Suzuki reactions of aryl bromide with aryl boronic acid. The monomeric complexes 2 and 3 are more active than the dimer 1. Palladium mirror was observed, indicating the involvement of classic Pd(0)/Pd(II) catalytic cycle using these cyclopalladated complexes. The coupling of aryl bromide with aryl boronic acid gave the desired biphenyl congeners in good to excellent yields. We tested the various bases, finding that inorganic bases work better than organic ones.

Keywords:

• Cyclopalladation
• Phosphorus ylide
• Catalyst
• Suzuki reaction

Acknowledgments

The author thanks the Isfahan University of Technology (IUT) Research Council and Center of Excellence in Sensor and Green Chemistry (IUT) for supporting this study.