Diversity Synthesis Using the Complimentary Reactivity of
Rhodium(II)- and Palladium(II)-Catalyzed Reactions
Aiwu Ni, Jessica E. France, and Huw M. L. Davies*
Department of Chemistry, UniVersity at Buffalo, The State UniVersity of New York,
Buffalo, New York 14260
ReceiVed March 23, 2006
Rhodium(II)-catalyzed reactions of aryldiazoacetates can be conducted in the presence of iodide, triflate,
organoboron, and organostannane functionality, resulting in the formation of a variety of cyclopropanes
or C-H insertion products with high stereoselectivity. The combination of the rhodium(II)-catalyzed
reaction with a subsequent palladium(II)-catalyzed Suzuki coupling offers a novel strategy for diversity
synthesis.
Introduction
type reaction/conjugation addition.7 In contrast, dimeric rhodium-
(II) complexes do not react with the common functionality used
in these coupling reactions, although they are exceptional
catalysts for the decomposition of diazo compounds.8 In this
paper we describe the application of the different but compli-
mentary reactivity of the rhodium(II)- and the palladium(II)-
catalyzed processes to a two-step sequence applicable to
diversity synthesis (eq 1).
Metal-catalyzed cross-coupling reactions have become broadly
applied in organic synthesis. Several important named reactions
such as the Suzuki,1 Stille,2 Negishi,3 and Sonagashira4 reactions
have been developed using this chemistry. The general process
relies on the oxidative addition of an organohalide or triflate to
a low-valent metal, followed by a metal-halogen (or triflate)
exchange with an organometallic species and then a reductive
elimination to complete the catalytic cycle. Organohalides and
triflates are the most common substrates for the initial oxidative
addition, and the reagents for the metal-halogen exchange are
typically Grignard, organozinc, organostannane, and organobo-
ron reagents. Palladium and nickel complexes are the best
catalysts for this chemistry, although a wide variety of other
metals will undergo oxidative addition with organohalides and
triflates. Rhodium(I) complexes are very effective catalysts in
a variety of reactions involving organohalides and/or organo-
metallics, such as reductive coupling,5 arylation,6 and Heck-
The development of transition-metal-induced cascade and
tandem reactions is of intense current interest.9 Recently, we
described a two-step sequence that combined ruthenium-
catalyzed enyne metathesis with rhodium-catalyzed tandem
cyclopropanation/Cope rearrangement into a rapid method for
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Espinet, P.; Echavarren, A. Angew. Chem., Int. Ed. 2004, 43, 4704.
(3) (a) Negishi, E. Acc. Chem. Res. 1982, 15, 340. (b) Negishi, E. J.
Organomet. Chem. 2002, 653, 34. (c) Negishi, E.; Anastasia, L. Chem. ReV.
2003, 103, 1979.
(4) (a) Tykwinski, R. R. Angew. Chem., Int. Ed. 2003, 42, 1566. (b)
Sonagashira, K. J. Organomet. Chem. 2002, 653, 46. (c) Sonagashira, K.
In ComprehensiVe Organic Synthesis; Trost, B. M., Fleming, I., Eds.;
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(6) (a) Bedford, R. B.; Limmert, M. E. J. Org. Chem. 2003, 68, 8669.
(b) Ueura, K.; Satoh, T.; Miura, M. Org. Lett. 2005, 7, 2229.
(7) (a) Ishiyama, T.; Hartwig, J. J. Am. Chem. Soc. 2000, 122, 12043.
(b) Herran, G.; Murcia, C.; Csaky, A. G. Org. Lett. 2005, 7, 5629.
(8) (a) Doyle, M. P.; Forbes, D. C. Chem. ReV. 1998, 98, 911. (b) Davies,
H. M. L.; Antoulinakis, E. G. J. Organomet. Chem. 2001, 617-618, 47.
(c) Padwa, A. J. Organomet. Chem. 2005, 690, 5533.
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10.1021/jo060636u CCC: $33.50 © 2006 American Chemical Society
Published on Web 06/20/2006
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J. Org. Chem. 2006, 71, 5594-5598