Highly Active, Air-Stable Palladium Catalysts for the C-C and C-S Bond-Forming Reactions of Vinyl and Aryl Chlorides: Use of Commercially Available Palladium-Phosphinous Acids Complexes as Catalysts
George Y. Li
DuPont Company, Central Research and Development Department, Experimental
Station, P.O. Box 80328, Wilmington, Delaware 19880-0328, Email:
george.y.li
combiphos.com
G. Y. Li, J. Org. Chem., 2002, 67, 3643-3650.
DOI: 10.1021/jo010983y
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Abstract
Air-stable palladium complexes with phosphinous acid ligands serve as efficient catalysts for various cross-coupling reactions of vinyl and aryl chlorides with arylboronic acids, arylzinc reagents, and thiols. The complexes can be deprotenated in the presence of a base to yield electron-rich anionic intermediates, which are anticipated not only to accelerate the oxidative addition of aryl chlorides but also to stabilize the palladium complexes in the catalytic cycle.
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Details
The document discusses the development and application of air-stable palladium(II) complexes, specifically [(t-Bu)2P(OH)]2PdCl2 (POPd), [(t-Bu)2P(OH)PdCl2]2 (POPd2), and [[(t-Bu)2PO-H-OP(t-Bu)2]PdCl]2 (POPd1), as efficient catalysts for cross-coupling reactions involving vinyl and aryl chlorides. These complexes facilitate the formation of carbon-carbon (C-C) and carbon-sulfur (C-S) bonds with arylboronic acids, arylzinc reagents, and thiols, yielding styrene derivatives, biaryls, and thioethers. The phosphinous acid ligands in these complexes can be deprotonated in the presence of a base, forming electron-rich anionic species that accelerate the rate-determining oxidative addition of aryl chlorides and stabilize the palladium complexes during the catalytic cycle. The study highlights the advantages of these air-stable complexes, including their simplicity, low cost, and high efficiency, making them practical for industrial applications. The document also provides detailed experimental procedures and characterization data for these complexes, demonstrating their effectiveness in various cross-coupling reactions under both inert and open-to-air conditions. The research underscores the potential of these palladium(II) complexes in synthetic chemistry, particularly for the construction of biaryls and aryl-heteroatom-containing frameworks.
Key Words
Suzuki Coupling, Negishi Coupling, Biaryl Synthesis, Akenylation, Thioether Synthesis
ID: J42-Y2002-450
