ORGANIC
LETTERS
2000
Vol. 2, No. 15
2385-2388
Suzuki Cross-Coupling Reactions
Catalyzed by Palladium Nanoparticles in
Aqueous Solution
,†
Yin Li,† Xiaoyong M. Hong, David M. Collard,* and Mostafa A. El-Sayed*
School of Chemistry and Biochemistry, Georgia Institute of Technology,
Atlanta, Georgia 30332-0400
Received June 6, 2000
ABSTRACT
Palladium nanoparticles stabilized by poly(N-vinyl-2-pyrrolidone) (PVP) are efficient catalysts for the Suzuki reactions in aqueous medium. The
time dependence of the fluorescence intensity of the biphenyl product in the reaction between iodobenzene and phenylboronic acid is used
to determine the initial rate of the catalytic reaction. The initial rate depends linearly on the concentration of Pd catalyst, suggesting that the
catalytic reaction occurs on the surface of the Pd nanoparticles.
The Suzuki cross-coupling reactions of arylboronic acids and
aryl halides provide an effective synthetic route to biaryls.1
The coupling reaction of arylboron derivatives with aryl
halides in the presence of Pd(PPh3)4 and base to afford biaryls
was first reported2 in 1981. A number of modifications have
appeared. These reactions are carried out in organic solvents
and catalyzed by various Pd/ligand systems.3 Phosphine-
based palladium catalysts are generally used. A combination
of Pd(PPh3)4 and aqueous Na2CO3 in dimethoxyethane
(DME) works satisfactorily for most Suzuki cross-couplings.4
However, in some cases the reactions can be catalyzed by
using other palladium catalysts such as Pd(OAc)2, [(η3-C3H5)-
PdCl]2, and Pd2(dba)3 C6H6.5 Nevertheless, one serious
problem in homogeneous metal catalysis is separation of the
reaction products from the catalyst. To solve this problem,
studies concerning coupling reactions in aqueous media using
water-soluble phosphine ligands such as sulfonated analogues
of triphenylphosphine6 so that Pd partitions into the aqueous
phase and the catalytic reaction proceeds in water have
already been carried out. The use of water as a reaction
medium for transition-metal-catalyzed reactions is very
attractive for organic synthesis, due to environmental,
economical, and safety reasons.
Colloidal metal particles are effective catalysts for chemi-
cal transformations due to their large surface area.7 It has
been shown that palladium colloids on the nanometer length
scale are effective catalysts for the Heck reaction8 (the
reaction between aryl halides and olefins) and the Suzuki
reaction9 in organic solvents. In these experiments, no
(6) (a) Casalnuovo, A. L.; Calabrese, J. C. J. Am. Chem. Soc. 1990, 112,
4324-4330. (b) Genet, J. P.; Linquist, A.; Blart, E.; Mouries, V.; Savignac,
M. Tetrahedron Lett. 1995, 36, 1443-1446. (c) Genet, J. P.; Savignac, M.
J. Organomet. Chem. 1999, 576, 305-317.
(7) Bradley J. S. In Clusters and Colloids: From Theory to Applications;
Schmid, G., Ed.; VCH: Weinheim, 1994; pp 523-536.
† Laser Dynamics Laboratory.
(1) (a) Miyaura, N.; Suzuki, A. Chem. ReV. 1995, 95, 2457-2483. (b)
Suzuki, A. J. Organomet. Chem. 1999, 576, 147-168. (c) Wolfe, J. P.;
Singer, R. A.; Yang, B. H.; Buchwald, S. L. J. Am. Chem. Soc. 1999, 121,
9550.
(2) Miyaura, N.; Yanagi, T.; Suzuki, A. Synth. Commun. 1981, 11, 513.
(3) Suzuki, A. In Metal-catalyzed Cross-Coupling Reactions; Diederich,
F., Stang, P. J., Ed.; VCH: Weinheim, 1998; pp 49-97.
(4) Alo, B. I.; Kandil, A.; Patil P. A.; Sharp, M. J.; Siddiqui, M. A.;
Snieckus, V.; Josephy, P. D. J. Org. Chem. 1991, 56, 3763-3768.
(5) (a) Wallow, T. I.; Novak, B. M. J. Org. Chem. 1994, 59, 5034-
5037. (b) Bumagin, N. A.; Bykov, V. V.; Beletskaya, I. P. Dokl. Akad.
Nauk. SSSR 1990, 315, 1133-1136. (c) Marck, G.; Villiger, A.; Buchecker,
R. Tetrahedron Lett. 1994, 35, 3277-3280.
(8) (a) Reetz, M. T.; Lohmer, G. Chem. Commun. 1996, 1921-1922.
(b) Beller, M.; Fischer, H.; Kuehlein, K.; Reisinger, C.-P.; Herrmann, W.
A. J. Organomet. Chem. 1996, 520, 257-259. (c) Klingelhoefer, S.; Heitz,
W.; Greiner, A.; Oestreich, S.; Foerster, S.; Antonietti, M. J. Am. Chem.
Soc. 1997, 119, 10116-10120. (d) Le Bars, J.; Specht, U.; Bradley, J. S.;
Blackmond, D. G. Langmuir 1999, 15, 7621-7625. (e) Ding, J. H.; Gin,
D. L. Chem. Mater. 2000, 12, 22-24.
(9) Reetz, M. T.; Breinbauer, R.; Wanninger, K. Tetrahedron Lett. 1996,
37, 4499-4502.
10.1021/ol0061687 CCC: $19.00 © 2000 American Chemical Society
Published on Web 06/29/2000