The Role of Ligand Transformations on the Performance of Phosphite- and Phosphinite-Based Palladium Catalysts in the Suzuki Reaction

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• 作者：Robin B. Bedford ; Samantha L. Hazelwood ; Michael E. Limmert ; John M. Brown ; Shailesh Ramdeehul ; Andrew R. Cowley ; Simon J. Coles ; and Michael B. Hursthouse
• 刊名：Organometallics
• 出版年：2003
• 出版时间：March 31, 2003
• 年：2003
• 卷：22
• 期：7
• 页码：1364 - 1371
• 全文大小：194K
• 年卷期：v.22,no.7(March 31, 2003)
• ISSN：1520-6041

文摘

The orthometalated complex [{Pd(-Cl){²-P,C-P(OC₆H₂-2,4-^tBu₂)(OC₆H₃-2,4-^tBu₂)₂}}₂]reacts with phenylboronic acid hydrate and K₂CO₃ in dimethylacetamide to give [Pd{²-P,C-²-O-P(O)(C₆H₂-2,4-^tBu₂)(C₆H₃-2,4-^tBu₂)(DMAc)}]. When the reaction is repeated indimethylformamide 3,3',5,5'-tetra-tert-butyl-2,2'-biphenol is isolated. Both compounds havebeen characterized crystallographically. The reaction of palladium dichloride with PⁱPr₂(OC₆H₄-4-Et) in 2-methoxyethanol followed by recrystallization in the presence of ethanolleads to the formation of trans-[PdCl₂{PⁱPr₂(OEt)}₂], which was also characterized bycrystallography. To determine whether related solvolytic processes have a bearing on catalyticactivity, the performance of a range of catalysts with "hydrolyzed" and "nonhydrolyzed"ligands was assessed in the Suzuki coupling of aryl bromides. In some cases it was evidentthat hydrolysis plays a significant role on the catalytic activity; however, this depends notonly on the ligand, but also on the combination of ligand and palladium precursor.