Convenient and Efficient Palladium-Catalyzed Coupling Reaction Between Ferroceneboronic Acid and Organic Triflates

Abstract

A simple and efficient palladium (Pd)–catalyzed Suzuki cross-coupling reaction between ferroceneboronic acid and organic triflates for the preparation of monosubstituted ferrocene derivatives has been developed. A systematic study of various solvents, bases, and catalysts revealed that the combination of Pd(PPh₃)₄ (0.025 equiv) and K₃PO₄ (2 equiv) in refluxing dioxane gave reproducible and excellent yields of the coupling products. The reaction could be applied to a wide variety of aryl and vinyl triflates in good to excellent yields, and the electronic and steric effects were observed for ortho-, meta-, and para-substituents of aryl triflates.

Keywords:

• Ferroceneboronic acid
• palladium catalyst
• Suzuki coupling
• triflates

ACKNOWLEDGMENTS

We are grateful for the financial support of the 985 Foundation of the Ministry of Education. This work was supported by the National Natural Science Foundation of China (Grant No. 20472018), the Natural Science Foundation of Hunan (Key Project No. 07JJ3019), the Doctoral Fund of Ministry of Education of China (Grant No. 20060532022), and the Department of Science and Technology Foundation of Changsha (Grant No. K082152-31).

Notes

^a Unless otherwise indicated, the reaction conditions were as follows: p-methylphenyl triflate (1 mmol), ferroceneboronic acid (1.2 mmol), catalyst (0.025 mmol), and base (2 mmol).

^b The reaction mixture was placed in an oil bath at stated temperature and held there for the allotted time.

^c Isolated yield based on p-methylphenyl triflate.