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Pd/C as a Reusable Catalyst for the Coupling Reaction of Halophenols and Arylboronic Acids in Aqueous Media

Hidehiro Sakurai, Tatsuya Tsukada and Toshikazu Hirao*

*Department of Applied Chemistry, Faculty of Engineering, Osaka University, Yamada-oka, Suita, Osaka 565-0871, Japan, Email: hiraoap.chem.eng.osaka-u.ac.jp

H. Sakurai, T. Tsukuda, T. Hirao, J. Org. Chem, 2002, 67, 2721-2722.

DOI: 10.1021/jo016342k


Abstract

The Suzuki-Miyaura coupling reaction of halophenols with ArB(OH)2 in aqueous K2CO3 solution is efficiently catalyzed by Pd/C. The palladium catalyst can be reused.

Halophenol
Boronic Acid
Yield (%, isol.)
2-Iodophenol PhB(OH)2 70
4-Iodophenol PhB(OH)2

run 1, 2, 3, 4, 5, 6 :
99, 95, 94, 90, 89, 89

4-Iodophenol 2-MeOC6H4B(OH)2 98
4-Bromophenol PhB(OH)2 35 (r.t.), 76 (50°C)

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Details

The document discusses the use of Pd/C as a reusable catalyst for the Suzuki-Miyaura coupling reaction of halophenols and arylboronic acids in aqueous media. This method offers a phosphine-free and environmentally friendly alternative to traditional coupling reactions, which often require toxic ligands and high temperatures. The study found that Pd/C effectively catalyzes the reaction, yielding hydroxybiaryls in high or quantitative yields. The catalyst can be easily recovered and reused multiple times with only a slight decrease in activity. The reaction conditions were optimized, showing that 0.3 mol % of Pd/C in aqueous K2CO3 solution at room temperature for 12 hours provided the best results. Various halophenols and arylboronic acids were tested, demonstrating the method's wide applicability. The experimental procedure involves simple steps, including stirring the reaction mixture, quenching with HCl, and separating the product via filtration and extraction. The study highlights the potential of Pd/C as a practical and sustainable catalyst for biaryl compound synthesis.


Key Words

Suzuki Coupling, Biaryls


ID: J42-Y2002-120