Immoblization of monodentate phosphoramidte ligands-rhodium complexes on mesoporous materials and its catalytic application in conjugate addition reaction of arylboronic acid to enones

• Main Author: Tan, Vivien Ying Shan.
• Other Authors: Yang Yanhui
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Science::Medicine::Pharmacy::Pharmaceutical technology
• Online Access: http://hdl.handle.net/10356/39402
• Institution: Nanyang Technological University

Due to the growing demand for enantio-pure compounds especially in the pharmaceutical industry, asymmetric catalysis has attracted extensive research effort over the past decades. Published literatures on the catalytic effect of monodentate ligands and the many advantages of heterogeneous catalysis have led to monodentate phosphoramidite—rhodium catalysts being the focus of this project. Hence, the immobilization of such ligands on mesoporous material, Santa Barbara Amorphous type material (SBA-15), through covalent bonding to yield its corresponding heterogenous catalyst was the main focus of this study. At the end of this study, monodentate phosphoramidite ligands were successfully immobilized on mesoporous SBA-15, whose ordered mesoporous structure was proven to be retained through XRD and nitrogen physisorption measurements. After the corresponding monodentate-phosphoramidite ligands were synthesized in both its homogenous and heterogeneous form, investigations on their catalytic effect on the conjugate addition reaction of arylboronic acids to cyclohexenones were carried out. Analysis results in this study showed that heterogeneous catalyst, Rh-PL1-MAn-SBA-15, gave improved activity and enantio-excess (ee) than its corresponding homogenous catalyst in the conjugate addition reaction. It was also concluded that a ligand-to-metal ratio of 1 provides optimal ee and conversion.