Organic Process Research & Development 2008, 12, 537–539
Communications to the Editor
A Practical and Improved Copper-Catalyzed Synthesis of the Central Intermediate of
Diafenthiuron and Related Products
†
†
‡
‡
,†
Thomas Schareina, Alexander Zapf, Alain Cotté, Nikolaus Müller, and Matthias Beller*
Leibniz-Institut für Katalyse e.V., an der UniVersität Rostock, Albert-Einstein-Strasse 29A, 18059 Rostock, Germany, and
Saltigo GmbH, Building Q 18-2, 51369 LeVerkusen, Germany
7,9,10
Until now mainly copper11 and pal-
Abstract:
Goldberg reactions.
12
ladium complexes evolved as catalysts for this type of reaction.
While palladium catalysts are more productive (catalyst turnover
numbers > 100) and active compared to copper, they have the
common disadvantage of high metal and ligand costs (and
sometimes the air-sensitivity of special phosphines). Although
a larger amount of metal has to be used, copper catalysis is
generally considered to be less expensive. Clearly, this statement
is only true for easily available copper precatalysts and ligands.
In this respect there is still a need for improved and more general
catalysts.
A bioinspired Cu(I)/N-methylimidazole catalyst system is used for
the synthesis of the diaryl ether part of diafenthiuron, a widely
used insecticide. The convenient protocol proceeds smoothly with
high selectivity and quantitative yield. Applying the optimized
procedure various diaryl ether analogs are synthesized in good to
excellent yield.
The diaryl ether moiety is present in numerous naturally
1
occurring and biologically active compounds. Important me-
dicinal products having this structural motif include polycyclic
Since 2004 we have developed new catalyst systems for the
2
3
glycopeptide antibiotics like vancomycin, teicoplanin, and the
13,14
cyanation of aryl halides based on palladium and copper.
4
antineoplastic agent combretastatin D-2. In addition, a number
of diaryl ethers are used in industrial polymers. Selected
Inspired by nature we assumed that imidazoles should be good
ligands to control the stability and selectivity of copper
5
examples are shown in Scheme 1.
15
catalysts. This idea resulted from the fact that the most
Until recently, the most general method for the synthesis of
diaryl ethers has been the classic copper-mediated Ullmann
coupling of aryl bromides/iodides and phenols with the draw-
back of harsh reaction conditions and the need of a stoichio-
metric amount of metal. Due to these problems significant
efforts have been undertaken in the past decade to develop more
efficient and environmentally benign coupling processes of
(
(
10) Ouali, A.; Spindler, J.-F.; Jutand, A.; Taillefer, M. AdV. Synth. Catal.
2
007, 349, 1906.
11) (a) Ullmann reactions with stoichiometric amounts of copper: Buck,
E.; Song, Z. J.; Tschaen, D.; Dormer, P. G.; Volante, R. P.; Reider,
P. J. Org. Lett. 2002, 4, 1623. (b) Wipf, P.; Jung, J. K. J. Org. Chem.
2
000, 65, 6319 With catalytic use of copper: (c) Miao, T.; Wang, L.
Tetrahedron Lett. 2007, 48, 95. (d) Lipshutz, B. H.; Unger, J. B.; Taft,
B. R. Org. Lett. 2007, 9, 1089. (e) Cai, Q.; Zou, B. L.; Ma, D. W.
Angew. Chem. 2006, 118, 1298; Cai, Q.; Zou, B. L.; Ma, D. W. Angew.
Chem., Int. Ed. 2006, 45, 1276. (f) Cristau, H.-J.; Cellier, P. P.;
Hamada, S.; Spindler, J.-F.; Taillefer, M. Org. Lett. 2004, 6, 913. (g)
Xu, L.-W.; Xia, C.-G.; Li, J.-W.; Hu, X.-X. Synlett 2003, 2071. (h)
Luo, Y. T.; Wu, J. X.; Ren, R. X. Synlett 2003, 1734. (i) Gujadhur,
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Marcoux, J. F.; Doye, S.; Buchwald, S. L. J. Am. Chem. Soc. 1997,
6
phenols. The current status of this improved methodology is
7
8
described in detail by Frlan and Kikelj, Beletskaya et al., and
9
by Kunz et al. Notably, several catalyst systems have been
developed, which enable aryl ether formation under much
milder conditions compared to the classical Ullmann and
1
19, 10539. (l) Kalinin, A. V.; Bower, J. F.; Riebel, P.; Snieckus, V.
*
To whom correspondence should be addressed. E-mail: matthias.beller@
J. Org. Chem. 1999, 64, 2986. (m) Pellón, R. F.; Docampo, M. L.
Synth. Commun. 2003, 33, 921. (n) Paine, A. J. J. Am. Chem. Soc.
1987, 109, 1496.
catalysis.de. Fax: 49 381 12815000. Telephone: 49 381 1281113.
†
Leibniz-Institut für Katalyse e.V.
Saltigo GmbH.
‡
(12) (a) Mann, G.; Incarvito, C.; Rheingold, A. L.; Hartwig, J. F. J. Am.
Chem. Soc. 1999, 121, 3224. (b) Aranyos, A.; Old, D. W.; Kiyomori,
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1999, 121, 4369. (c) Harkal, S.; Kumar, K.; Michalik, D.; Zapf, A.;
Jackstell, R.; Rataboul, F.; Riermeier, T.; Monsees, A.; Beller, M.
Tetrahedron Lett. 2005, 46, 3237.
(
(
1) Ley, S. V.; Thomas, A. W. Angew. Chem. 2003, 115, 5558; Ley,
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(
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(13) (a) Schareina, T.; Zapf, A.; Mägerlein, W.; Müller, N.; Beller, M.
Synlett 2007, 555. (b) Schareina, T.; Zapf, A.; Mägerlein, W.; Müller,
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(
(
(14) (a) Schareina, T.; Zapf, A.; Mägerlein, W.; Müller, N.; Beller, M.
Tetrahedron Lett. 2007, 48, 1087. (b) Schareina, T.; Zapf, A.; Beller,
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(
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984, 40, 1433.
(
(
7) Frlan, R.; Kikelj, D. Synthesis 2006, 2271.
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(15) For recent work on Fe catalysts with imidazole ligands, see: Schr o¨ der,
K.; Tong, X.; Bitterlich, B.; Tse, M. K.; Gelalcha, F. G.; Br u¨ ckner,
A.; Beller, M. Tetrahedron Lett. 2007, 48, 6339.
2
337.
(
9) Kunz, K.; Scholz, U.; Ganzer, D. Synlett 2003, 2428.
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0.1021/op700287s CCC: $40.75
2008 American Chemical Society
Vol. 12, No. 3, 2008 / Organic Process Research & Development
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Published on Web 04/10/2008