Highly active organosilane-based N-heterocyclic carbene-palladium complex immobilized on silica particles for the Suzuki reaction*
Sang-Myung Lee, Hyo-Jin Yoon, Jong-Ho Kim, Woo-Jae Chung, and Yoon-Sik Lee
School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Korea
Abstract: 1-Methyl-3-(3-trimethoxysilylpropyl)imidazolium chloride, [TMSPIM][Cl-], was synthesized as a precursor of N-heterocyclic carbene (NHC), which can be coordinated with palladium to give an organosilane-based bidentic NHC-Pd complex. The organosilane-based NHC-Pd complex was immobilized covalently on silica particles (NHC-Pd/silica) and then characterized by field emission/scanning electron microscopy (FE/SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIRS), and inductively coupled plasma/atomic emission spectroscopy (ICP/AES). The Suzuki reaction was performed as a model reaction to examine the catalytic activity of NHC-Pd/silica. NHC-Pd/silica exhibited excellent performance in the Suzuki reaction of various aryl halide derivatives (except for aryl chloride derivatives) with phenylboronic acid under mild conditions (room temperature and short reaction time). Moreover, the catalyst was recycled several times without any significant loss of catalytic activity in the Suzuki reaction.
Keywords: N-heterocyclic carbene; Suzuki reaction; palladium; silica; organosilane.
*Paper based on a presentation at the 12th International Conference on Polymers and Organic Chemistry 2006 (POC'06), 2-7 July 2006, Okazaki, Japan. Other presentations are published in this issue, pp. 1471-1582.