ORGANIC
LETTERS
2005
Vol. 7, No. 11
2209-2211
Arylation of Diarylamines Catalyzed by
Ni(II) PPh3 System
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Chen Chen†,‡ and Lian-Ming Yang*,†
Institute of Chemistry, Chinese Academy of Sciences, Beijing, P. R. China, and
Graduate School of Chinese Academy of Sciences, Beijing, P. R. China
Received March 21, 2005
ABSTRACT
The cross-coupling of bromomagnesium diarylamides, generated in situ from diarylamines, with aryl bromides or iodides can be effected with
a simple NiCl2(PPh3)2 PPh3 catalyst system under relatively mild conditions. This coupling reaction is an inexpensive, convenient, and practical
method, functioning as an alternative to the corresponding Pd-catalyzed or Cu-mediated process for the synthesis of triarylamines.
−
Transition-metal-catalyzed cross-couplings between aryl-
amines and aryl halides represent a powerful tool for the
construction of triarylamines. These amines are an extremely
important unit of organic materials with interesting electronic,
photoelectronic, and magnetic properties and are extensively
used in organic light-emitting diodes, photovoltaic cells,
nonlinear optics, and organic photoconductors, etc.1 So far,
both the Ullmann-type reactions (Cu-mediated)2 and the
Buchwald-Hartwig methods (Pd-catalyzed)3 have made
remarkable advances in the formation of various C-N bonds,
among which were syntheses of triarylamines from arylation
of anilines and diarylamines.4,5 However, in Pd-catalyzed
processes, the high cost of palladium and the special ligands
required to activate it limit its use at least in the large-scale
preparation of triarylamines. And for Cu-catalyzed triaryl-
amine syntheses, either expensive ligands or defined sub-
strates such as aryl iodides are required to obtain good yields.
In striking contrast, cheap and practical nickel-based cata-
lysts, being a well-established partner of palladium catalysts
in C-C bond-forming reactions, have not been fully
developed in the C-N bond construction, and there are only
a few reports on Ni-catalyzed halide amination in which
dialkylamines and/or anilines were mainly involved.6 Our
desire to pursue an inexpensive, convenient, and mild
procedure for scalable synthesis of triarylamine compounds
prompted us to explore the feasibility of employing a
combination of Ni-based catalysts and the most common
ligands such as triphenylphosphine. To our knowledge, the
Ni-catalyzed cross-coupling between diarylamines and aryl
halides has not been reported. Herein, we describe our initial
results on the first Ni-catalyzed arylation of diarylamines
with unactivated aryl bromides or iodides.
† Institute of Chemistry, Chinese Academy of Sciences.
‡ Graduate School of Chinese Academy of Sciences.
(1) (a) Louie, J.; Hartwig, J. F. J. Am. Chem. Soc. 1997, 119, 11695-
11696. (b) Chou, M.-Y.; Leung, M.-K.; Su, Y. O.; Chiang, C. L.; Lin, C.-
C.; Liu, J.-H.; Kuo, C.-K. Mou, C.-Y. Chem. Mater. 2004, 16, 654-661.
For reviews, see: (c) Strohriegl, P.; Grazulevicius, J. V. AdV. Mater. 2002,
14, 1439-1452. (d) Shirota, Y. J. Mater. Chem. 2000, 10, 1-25.
(2) (a) Ullmann, F. Chem. Ber. 1903, 36, 2382-2384. For reviews, see:
(b) Lindley, J. Tetrahedron 1984, 40, 1433-1456. (c) Beletskaya, I. P.;
Cheprakov, A. V. Coord. Chem. ReV. 2004, 248, 2337-2364.
(3) For reviews, see: (a) Muci, A. R.; Buchwald, S. L. Practical
Palladium Catalysts for C-N and C-O Bond Formation. In Topics in
Current Chemistry; Miyaura, N., Ed.; Springer-Verlag: Berlin, 2002; Vol.
219, p 133. (b) Hartwig, J. F. Angew. Chem., Int. Ed. 1998, 37, 2046-
2067. (c) Tsuji, J. Palladium Reagents and Catalysts: InnoVations in
Organic Synthesis; Wiley: New York, 1996.
(5) For representative references: (a) CuI/P(Bu)3 system, see: Patil, N.
M.; Kelkar, A. A.; Nabi, Z.; Chaudhari, R. V. Chem. Commun. 2003, 2460-
2461. (b) Cu(I)/neocufroine, see: Gujadhur, R. K.; Bates, C. G.; Venkat-
araman, D. Org. Lett. 2001, 3, 4315-4317. (c) Cu(I)/1,10-phenanthroline
system, see: Goodbrand, H. B.; Hu, N. X. J. Org. Chem. 1999, 64, 670-
674.
(4) For representative referenes: (a) Pd(0)/biphenyl-based phosphane
system, see: Ali, M. H.; Buchwald, S. L. J. Org. Chem. 2001, 66, 2560-
2565. (b) Pd(0)/P(t-Bu)3 or DPPF system, see: Louie, J.; Hartwig, J. F.
Macromolecules 1998, 31, 6737-6739. (c) Pd(0)/DPPF or P(o-tolyl)3
system, see ref 1a.
(6) For recent selected literature, see: (a) Wolfe, J. P.; Buchwald, S. L.
J. Am. Chem. Soc. 1997, 119, 6054-6058. (b) Brenner, E.; Schneider, R.;
Fort, Y. Tetrahedron 1999, 55, 12829-12842. (c) Lipshutz, B. H.; Ueda,
H. Angew. Chem., Int. Ed. 2000, 39, 4492-4494. (d) Tasler, S.; Lipshutz,
B. H. J. Org. Chem. 2003, 68, 1190-1199.
10.1021/ol050608i CCC: $30.25
© 2005 American Chemical Society
Published on Web 04/28/2005