ORGANIC
LETTERS
2000
Vol. 2, No. 7
879-882
Pd(DIPHOS)2-Catalyzed Cross-Coupling
Reactions of Organoborons with Free or
Polymer-Bound Aryl Halides†
Dibyendu De* and Donald J. Krogstad‡
Departments of Tropical Medicine and Chemistry and the Center for Infectious
Diseases, Tulane UniVersity, New Orleans, Louisiana 70112
Received December 15, 1999
ABSTRACT
Bis[1,2-bis(diphenylphosphino)ethane]palladium(0) [Pd(DIPHOS)2] catalyzes cross-coupling reactions of free or polymer-bound aryl halides
with organoboron compounds to produce biaryls in overall yields of 60−96%.
Palladium-catalyzed Suzuki cross-couplings are important
strategies for organic synthesis.1,2 These coupling reactions
offer a powerful tool for the formation of C-C bonds. In
the past few years a number of methods have been developed
which permit the use of organoboron compounds that are
thermally stable and inert to water and oxygen.2b Further,
these coupling reactions have been used successfully for the
synthesis of natural products,3a,b pharmaceutical intermediates,3c
and combinatorial libraries of organic compounds.4 Suzuki
couplings likely follow a catalytic cycle, which is initiated
by the oxidative addition of organic halides to the Pd species
and followed by transmetalation of the Ar group from boron
to Pd.2d,e After transmetalation, the reaction proceeds smoothly
when it has been activated by a suitable base.
Despite the broad synthetic utility of Pd(PPh3)4 in cross-
coupling reactions, it is air and light sensitive and often forms
a number of byproducts in these reactions.5 Thus, a wide
range of Pd catalysts has been employed for the synthesis
of biaryls including Pd(OAc)2 plus PPh3 which is reported
to be rapidly reduced to Pd(0) complexes with phosphines
in situ.2d,6
As part of our research we were interested in a simple,
straightforward, and reliable method for cross-coupling
reactions. Herein we report the Pd(DIPHOS)2-catalyzed
coupling of aryl halides with organoboron compounds.
† Presented in part at the following: De, D.; Krogstad, D. J. Palladium
catalyzed coupling of aryl bromides with aryl boranes, alkenes, and alkynes
to produce biaryls, substituted alkenes, and alkynes. In Abstracts of Papers,
218th National Meeting of the American Chemical Society, New Orleans,
LA; American Chemical Society; Washington, DC, 1999; ORGN 595.
‡ Also
mailhost.tcs.tulane.edu.
available
for
correspondence.
Email:
krogstad@
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Organic Synthesis; John Wiley & Sons: Chichester, England, 1995. (b)
Tsuji, J. Organic Synthesis with Palladium compounds; Springer-Verlag:
Berlin, 1980.
(2) (a) Suzuki, A. Metal-Catalyzed Cross Coupling Reactions; Driederich,
F., Stang, P. J., Eds.; Wiley-VCH: Weinheim, Germany, 1998. (b) Miyaura,
N.; Suzuki, A. Chem. ReV. 1995, 95, 2457. (c) Miyaura, N.; Yamada, K.;
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B.; Dezeny, G. C.; Hughes, D. L.; King, A. O.; Verhoeven, T. R. J. Org.
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Org. Chem. 1996, 61, 2346.
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Chem. 1990, 55, 5324. (c) Shieh, W. C.; Carlson, J. A. J. Org. Chem. 1992,
57, 379.
(4) (a) Thompson, L. A.; Moore, F. L.; Moon, Y.-C.; Ellman, J. A. J.
Org. Chem. 1998, 63, 2066. (b) Lorsbach, B. A.; Bagdanoff, J. T.; Miller,
R. B.; Kurth, M. J. J. Org. Chem. 1998, 63, 2244. (c) Bleicher, K. H.;
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(7) (a) Genet, J. P.; Balabane, M.; Backvall, J. E.; Nystrom, J. E.
Tetrahedron Lett. 1983, 24, 2745. (b) Ferrona, D.; Genet, J. P.; Kiolle, R.
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Chem. Soc. Jpn. 1972, 45, 1183.
(8) Abbreviations: Pd(PPh3)4 {(tetrakistriphenylphosphine)palladium};
Pd(DIPHOS)2 {bis[1,2-bis(diphenylphosphino)ethane]palladium}; Pd2(dba)3
{(dibenzylideneacetone)dipalladium}; PdCl2(dppf) {[1,1′-bis(diphenylphos-
phino)ferrocene]palladium dichloride}; PdCl2(PPh3)2 {bis(triphenyl-phos-
phine)palladium dichloride}.
10.1021/ol991356m CCC: $19.00 © 2000 American Chemical Society
Published on Web 03/17/2000