Novel Class of Tertiary Phosphine Ligands Based on a Phospha-adamantane Framework and Use in the Suzuki Cross-Coupling Reactions of Aryl Halides under Mild Conditions
George Adjabeng, Tim Brenstrum, Jeffrey Wilson, Christopher Frampton, Al Robertson, John Hillhouse, James McNulty and Alfredo Capretta*
*Institute of Molecular Catalysis, Department of Chemistry, Brock
University, St. Catharines, Ontario L2S 3A1, Canada, Email:
fcaprett
chemiris.labs.brocku.ca
G. Adjabeng, T. Brenstrum, J. Wilson, C. Frampton, A. Robertson, J. Hillhouse, J. McNulty, A. Capretta, Org. Lett., 2003, 5, 953-955.
DOI: 10.1021/ol0341647
Abstract
A catalytic system incorporating Pd2(dba)3 and 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phenyl-6-phospha-adamantane as sterically hindered phosphine ligand promotes the Suzuki cross-coupling of aryl iodides, bromides, and activated chlorides with various aryl boronic acids at room temperature in a few hours with high yields.
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Details
The document discusses a novel class of sterically hindered tertiary phosphine ligands based on a phospha-adamantane framework, developed for use in palladium-catalyzed Suzuki cross-coupling reactions. These ligands, derived from 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phospha-adamantane, facilitate the efficient coupling of aryl iodides, bromides, and activated chlorides with aryl boronic acids at room temperature, yielding high conversions within a few hours. The study highlights the advantages of these ligands, such as their air stability, cost-effectiveness, and ease of handling compared to other commonly used ligands like P(tBu)3. The research demonstrates that palladium complexes with these ligands are highly active, even for challenging aryl chlorides. The ligands can be fine-tuned by incorporating various aryl or alkyl groups, enhancing their steric and electronic properties. The findings suggest that these new ligands could be beneficial for other metal-promoted cross-coupling reactions, with ongoing investigations to explore further applications. The work was supported by the Natural Sciences and Engineering Research Council of Canada, and additional experimental details are available online.
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Key Words
ID: J54-Y2003-360
