Communications
[4] For the reaction of aryl palladium complexes with acetic
anhydride, see: S. Cacchi, G. Fabrizi, F. Gavazza, A. Goggia-
mani, Org. Lett. 2003, 5, 289 – 291.
s-aryl palladium moiety and the alkoxycarbonyl group would
then lead to the PdII alkoxide A. The coordination of the
N atom to the palladium center in 16 not only brings the
carbonyl group nearer to the metal to facilitate the formation
of a transient chelated intermediate in which the carbonyl
group is coordinated to the palladium center,[14] but also
increases the electron density on the palladium center to
enable the otherwise unfavorable carbopalladation reaction
to occur. b-Alkoxide elimination from A would afford ketone
2 and a PdII alkoxide, which would finally undergo b-hydride
elimination to regenerate the Pd0 catalyst. The isolation of
significant amounts of benzaldehyde in the reaction of benzyl
ester 4c supports this reduction sequence.[15]
[5] For the reaction of aryl and vinyl palladium complexes with
nitriles, see: a) C.-C. Yang, P.-J. Sun, J.-M. Fang, J. Chem. Soc.
Chem. Commun. 1994, 2629 – 2630; b) R. C. Larock, Q. Tian,
A. A. Pletnev, J. Am. Chem. Soc. 1999, 121, 3238 – 3239; c) A. A.
Pletnev, Q. Tian, R. C. Larock, J. Org. Chem. 2002, 67, 9276 –
9287; d) A. A. Pletnev, R. C. Larock, J. Org. Chem. 2002, 67,
9428 – 9438; e) Q. Tian, A. A. Pletnev, R. C. Larock, J. Org.
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Org. Chem. 2006, 71, 3551 – 3558; h) B. Zhao, X. Lu, Tetrahedron
Lett. 2006, 47, 6765– 6768; see also ref. [2c].
[6] The few Pd-mediated reactions in which an ester functionality is
modified do not involve the carbopalladation of the carbonyl
group; see, for example: a) W. Tao, L. J. Silverberg, A. L.
Rheingold, R. F. Heck, Organometallics 1989, 8, 2550 – 2559;
b) R. C. Larock, X. Han, M. J. Doty, Tetrahedron Lett. 1998, 39,
5713 – 5716.
In summary, we have described the first examples of a
palladium-catalyzed acylation of aryl iodides by alkoxycar-
bonyl groups. Further studies to expand the intramolecular
reaction and provide deeper insight into the mechanism are
under way.
[7] For recent reviews, see: a) G. C. Lloyd-Jones, Angew. Chem.
2002, 114, 995– 998; Angew. Chem. Int. Ed. 2002, 41, 953 – 956;
b) D. A. Culkin, J. F. Hartwig, Acc. Chem. Res. 2003, 36, 234 –
245.
Experimental Section
[8] a) W. A. Moradi, S. L. Buchwald, J. Am. Chem. Soc. 2001, 123,
7996 – 8002; b) S. Lee, N. A. Beare, J. F. Hartwig, J. Am. Chem.
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Am. Chem. Soc. 2004, 126, 5182 – 5191.
Typical procedure: A mixture of the amino ester (0.04m), K3PO4
(3 equiv), Et3N (10 equiv), and [Pd(PPh3)4] (20 mmol%) in toluene
was stirred at 1108C in a sealed tube for 72 h. The reaction mixture
was then poured into water, and the resulting mixture was extracted
with Et2O. The organic extracts were washed with brine, dried, and
concentrated. The residue was purified by flash chromatography to
give the corresponding dihydroquinolin-4-one.
[9] O. Gaertzen, S. L. Buchwald, J. Org. Chem. 2002, 67, 465– 475.
[10] a) A. B. Daruwala, J. E. Gearien, W. J. Dunn III, P. S. Benoit, L.
Bauer, J. Med. Chem. 1974, 17, 819 – 824; b) K. Nishijima, T.
Shinkawa, Y. Yamashita, N. Sato, H. Nishida, K. Kato, Y. Onuki,
M. Mizota, K. Ohmoto, S. Miyano, Eur. J. Med. Chem. 1998, 33,
267 – 277.
Received: May 17, 2007
Published online: August 14, 2007
Keywords: acylation · cyclization · nitrogen heterocycles ·
.
nucleophilic substitution · palladium
[11] The reduction is a common side reaction in such processes; see,
for example, refs. [3b,c,5d].
[12] The Pd0-catalyzed intramolecular coupling of amino-tethered
vinyl halides with esters also proceeds without any interference
from nucleophilic attack at the ester group; the addition of a
phenoxide to the reaction mixture is necessary to promote the
reaction at the a position; see: D. SolØ, X. Urbaneja, J. Bonjoch,
Adv. Synth. Catal. 2004, 346, 1646 – 1650.
[1] Handbook of Organopalladium Chemistry for Organic Synthesis,
Vols. I and II (Ed.: E. Negishi), Wiley-VCH, New York, 2002.
[2] For the reaction of aryl and vinyl palladium complexes with
aldehydes, see: a) R. C. Larock, M. J. Doty, S. Cacchi, J. Org.
Chem. 1993, 58, 4579 – 4583; b) V. Gevorgyan, L. G. Quan, Y.
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X. Lu, Angew. Chem. 2002, 114, 4519 – 4521; Angew. Chem. Int.
Ed. 2002, 41, 4343 – 4345; d) J. Vicente, J.-A. Abad, B. López-
Pelµez, E. Martínez-Viviente, Organometallics 2002, 21, 58 – 67.
[3] For the reaction of aryl and vinyl palladium complexes with
ketones, see: a) L. G. Quan, V. Gevorgyan, Y. Yamamoto, J. Am.
Chem. Soc. 1999, 121, 3545 – 3546; b) L. G. Quan, M. Lamrani,
Y. Yamamoto, J. Am. Chem. Soc. 2000, 122, 4827 – 4828; c) D.
SolØ, L. Vallverdffl, X. Solans, M. Font-Bardia, J. Bonjoch, J. Am.
Chem. Soc. 2003, 125, 1587 – 1594; d) G. Liu, X. Lu, J. Am.
Chem. Soc. 2006, 128, 16504 – 16505; see also ref. [2c–d].
[13] For a related rhodium(I)-catalyzed transformation, see: T.
Miura, T. Sasaki, H. Nakazawa, M. Murakami, J. Am. Chem.
Soc. 2005, 127, 1390 – 1391.
[14] For the intramolecular coordination of the ester carbonyl group
to PdII, see: S. Gosiewska, M. Huis inꢀt Veld, J. J. M. de Pater,
P. C. A. Bruijnincx, M. Lutz, A. L. Spek, G. van Koten, R. J. M.
Klein Gebbink, Tetrahedron: Asymmetry 2006, 17, 674 – 686.
[15] The involvement of other reductants (e.g. Et3N) can not be
excluded completely; see: S.-I. Murahashi, T. Hirano, T. Yano, J.
Am. Chem. Soc. 1978, 100, 348 – 350.
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