Sustainable Suzuki-Miyaura Reaction Catalyzed by Pd(OAc)₂ Immobilized on Reversed-Phase Alumina

Abstract

Employing Pd(OAc)₂ immobilized on amorphous N,N-diethylaminopropyl alumina, Suzuki-Miyaura coupling of aryl halide with arylboronic acid was realized in 50% aqueous ethanol at room temperature, which enabled repeated use up to four times in 96% average yield and achieved a turnover number of 15 000.

Key words

arylations - boron - cross-coupling - heterogeneous catalysis - palladium - supported catalysis

References and Notes

• 1a Recent reviews: Miyaura N. Suzuki A. Chem. Rev.  1995,  95:  2457 
• 1b Hassan J. Sévignon M. Gozzi C. Schulz E. Lemaire M. Chem. Rev.  2002,  102:  1359 
• 1c Miyaura N. Top. Curr. Chem.  2002,  219:  11 
• 1d Kotha S. Lahiri K. Kashinath D. Tetrahedron  2002,  58:  9633 
• 1e Littke AF. Fu GC. Angew. Chem. Int. Ed.  2002,  41:  4176 
• 2 Rouhi AM. Chem. Eng. News  2004,  82 (36):  49 
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• For our representative efforts in this area, see:
• 5a Hagiwara H. Inotsume S. Fukushima M. Hoshi T. Suzuki T. Chem. Lett.  2006,  35:  926 
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• 5c Hagiwara H. Numamae A. Isobe K. Hoshi T. Suzuki T. Heterocycles  2006,  68:  889 ; and earlier references cited therein
• For some selected Suzuki-Miyaura reactions in aqueous alcohol, see:
• 6a Marck G. Villiger A. Buchecker R. Tetrahedron Lett.  1994,  35:  3277 
• 6b Liu L. Zhang Y. Xin B. J. Org. Chem.  2006,  71:  3994 
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• 6f Hagiwara H. Ko KH. Hoshi T. Suzuki T. Chem. Commun.  2007,  2838 
• 8 Arvela RK. Leadbeater NE. Sangi MS. Williams VA. Granados P. Singer RD. J. Org. Chem.  2005,  70:  161 

7

Typical Experimental Procedure: To a stirred solution of 4-bromoacetophenone (96 mg, 0.48 mmol), 4-acetylphen-ylboronic acid (110 mg, 0.67 mmol), and K₂CO₃ (141 mg, 1 mmol) in EtOH (1 mL) and H₂O (1 mL) was added NDEAP-Al₂O₃-Pd(OAc)₂ (256 mg, Pd loading: 0.1 mmol/g alumina, 0.026 mmol). After stirring for 5 min, the product was triturated with EtOAc several times. The combined organic layer was evaporated to dryness and the residue was purified by column chromatography (CH₂Cl₂-n-hexane, 3:10) to provide a biaryl product (121 mg, 100%).