| Author: | Wong, Shun Man |
| Title: | Design and synthesis of hemilabile heterocyclic phosphine Ligands and their applications in palladium-catalyzed carbon-carbon and carbon-nitrogen bond-construction processes |
| Advisors: | Kwong, Fuk Yee (ABCT) |
| Degree: | Ph.D. |
| Year: | 2015 |
| Subject: | Phosphorus compounds. Ligands (Biochemistry) Catalysis. Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Applied Biology and Chemical Technology |
| Pages: | 1 volume (various pagings) : illustrations ; 30 cm |
| Language: | English |
| Abstract: | A new family of hemilabile benzimidazolyl phosphine ligands was designed and synthesized. The benzimidazole scaffold of this family of ligands could be easily prepared and diversified from inexpensive substituted o-phenylenediamines and substituted carboxylic acids by conventional Phillips benzimidazole synthesis. Two classes of ligands, P,N-type 2-arylated benzimidazolyl phosphine ligands and alterable P,O-or P,N-type 2-phosphino-substituted benzimidazolyl ligands, were successfully synthesized by a “Cross-matching approach. The 2-arylated benzimidazolyl phosphine ligands showed excellent catalytic activities for the Suzuki-Miyaura coupling of aryl chlorides with arylboronic acids, especially under very-low-catalyst-loading down to 1 ppm. In addition, these ligands were efficient towards Suzuki-Miyaura coupling of aryl chlorides with potassium aryltrifluoroborates. Notably, the X-ray crystallographic data confirmed that the ligand was coordinated in a κ2-P,N fashion to the palladium center. On the other hand, the palladium complexes of 2-phosphino-substituted benzimidazolyl ligands showed coordination in a κ2-P,N fashion and potential P,O-hemilabile ability, which could be altered by tuning the steric bulkiness of phosphino group. Interestingly, the complexes with P,O-coordination and P,N-coordination showed high efficacy towards Suzuki-Miyaura coupling and Buchwald-Hartwig amination of aryl chlorides, respectively. Particularly noteworthy, to probe with these fascinating hemilabile properties, chemoselective cross-coupling of aryl chlorides was also examined. The palladium-ligand complexes showed essentially complete orthogonal property (>99%) to afford Suzuki coupling products when carrying out competitive cross-coupling of aryl chlorides with arylboronic acids and amines. |
| Rights: | All rights reserved |
| Access: | open access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| b27981848.pdf | For All Users | 21.28 MB | Adobe PDF | View/Open |
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