Macroporous Polystyrene-Supported Palladium Catalyst Containing a Bulky N-Heterocyclic Carbene Ligand for Suzuki Reaction of Aryl Chlorides Dong-Ho Lee, ² Jong-Ho Kim, ²,§ Bong-Hyun Jun, ² Homan Kang, ‡ Juyoung Park, ² and Yoon-Sik Lee* ,²,‡ School of chemical and Biological Engineering, Seoul National UniVersity, Interdisciplinary Program in Nano-science and Technology, Seoul National UniVersity, Seoul 151-744, South Korea yslee@snu.ac.kr Received February 11, 2008 ABSTRACT Macroporous polystyrene (MPS)-supported 1-mesitylimidazolium chloride resin was prepared by reacting macroporous chloromethyl polystyrene with 1-mesitylimidazole as a supported N-heterocyclic carbene (NHC) precursor for the immobilization of a palladium catalyst. This MPS- supported NHC precursor readily formed a stable complex with Pd(OAc) 2 , which effectively catalyzed the Suzuki reaction of aryl iodide and bromides at room temperature and even aryl chlorides at elevated temperatures (100 °C). This catalyst showed reusability in the Suzuki reaction of aryl bromide. The Suzuki reaction catalyzed by palladium is one of the most powerful routes for the formation of C(sp 2 )-C(sp 2 ) bonds. This reaction has been used to make biaryl derivatives that are important intermediates in polymers, liquid crystals, pharmaceuticals, and herbicides. 1,2 From an industrial point of view, one of significant issue in the Suzuki reaction has focused on aryl chlorides because they are cheaper than aryl iodides and bromides and are readily available. 3 Over the past few years, the Suzuki reaction of aryl chlorides were carried out successfully using homogeneous catalysts. 4 However, homogeneous catalysts have several problems, such as the need to separate and recycle the catalysts and the contamination from ligand residues in products. Therefore, a heterogeneous catalyst for the Suzuki reaction of aryl chlorides is still needed for industrial applications. Recently, several types of heterogeneous cata- lysts in the Suzuki reaction of aryl chlorides were reported using mesoporous silica-supported palladium catalysts, 5 Pd/C ² School of Chemical and Biological Engineering. ‡ Interdisciplinary Program in Nano-science and Technology. § Current address: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139. (1) (a) Miyaura, N.; Yanagi, T.; Suzuki, A. Synth. Commun. 1981, 11, 513. (b) Miyaura, N.; Suzuki, A. Chem. ReV. 1995, 95, 2457. (c) Suzuki, A. J. Organomet. Chem. 1999, 576, 147. (2) For recent reviews, see: (a) Bellina, F.; Carpita, A.; Rossi, R. Synthesis 2004, 2419. (b) Pershichini, P. J. Curr. Org. Chem. 2003, 7, 1725. (c) Hassan, J.; Sevignon, M.; Gozzi, C.; Schulz, E.; Lemaire, M. Chem. ReV. 2002, 102, 1359. (d) Kotha, S.; Lashiri, S.; Kashinath, D. Tetrahedron 2002, 58, 9633. (3) Review: (a) Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. 2002, 41, 4176. (b) Bedford, R. B.; Cazin, C. S. J.; Holder, D. Coord. Chem. ReV. 2004, 248, 2283. (4) (a) Zapf, A.; Ehrentraut, A.; Beller, M. Angew. Chem., Int. Ed. 2000, 39, 4153. (b) Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. 1998, 37, 3387. (c) Stu¨rmer, R. Angew. Chem., Int. Ed. 1999, 38, 3307. (d) Old, D. W.; Wolfe, J. P.; Buchwald, S. L. J. Am. Chem. Soc. 1998, 120, 9722. (e) Zhang, C.; Huang, J.; Trudell, M. L.; Nolan, S. P. J. Org. Chem. 1999, 64, 3804. (f) Bohn, V. P. W.; Gstottmayer, C. W. K.; Weskamp, T.; Herrmann, W. A. J. Organomet. Chem. 2000, 595, 186. (5) (a) Yang, Q.; Ma, S.; Li, J.; Xiao, F.; Xiong, H. Chem. Commun. 2006, 2495. (b) Trilla, M.; Pleixats, R.; Man, M. W. C.; Bied, C.; Moreau, J. J. E. Tetrahedron Lett. 2006, 47, 2399. (c) Sayah, R.; Glegola, K.; Framery, E.; Dufaud, V. AdV. Synth. Catal. 2007, 349, 373. ORGANIC LETTERS 2008 Vol. 10, No. 8 1609-1612 10.1021/ol8003047 CCC: $40.75 © 2008 American Chemical Society Published on Web 03/20/2008