Serena Fantasia et al.
COMMUNICATIONS
[6] Q. Shen, J. F. Hartwig, J. Am. Chem. Soc. 2006, 128,
10028.
and more available – the use of gaseous ammonia will
no longer be hampered by technical issues.
[7] a) D. S. Surry, S. L. Buchwald, J. Am. Chem. Soc. 2007,
129, 10354; b) T. Schulz, C. Torborg, S. Enthaler, B.
Schꢁffner, A. Dumrath, A. Spannenberg, H. Neumann,
A. Bçrner, M. Beller, Chem. Eur. J. 2009, 15, 4528;
c) G. D. Vo, J. F. Hartwig, J. Am. Chem. Soc. 2009, 131,
11049; d) R. J. Lundgren, B. D. Peters, P. G. Alsabeh,
M. Stradiotto, Angew. Chem. 2010, 122, 4165; Angew.
Chem. Int. Ed. 2010, 49, 4071; e) D. Tsvelikhovsky,
S. L. Buchwald, J. Am. Chem. Soc. 2011, 133, 14228;
f) A. Dumrath, C. Lꢂbbe, H. Neumann, R. Jackstell,
M. Beller, Chem. Eur. J. 2011, 17, 9599.
Experimental Section
General Procedure for the Amination of Aryl
Bromides 1a–13a
A 35-mL glass-lined stainless steel autoclave (Premex reac-
tor AG) was charged with the aryl bromide (if solid,
5 mmol, 1 equiv.), K3PO4 (1.06 g, 5 mmol, 1 equiv.) and Cu-
ACHTUNGTRENNUNG(acac)2 (65.5 mg, 0.25 mmol, 0.05 equiv.). The autoclave was
[8] The early systems suffered from harsh reaction condi-
tions such as temperature above 1508C and the need of
liquid ammonia and/or stoichiometric amount of
copper: a) J. Lindley, Tetrahedron 1984, 40, 1433; b) E.
Vedejs, P. Trapencieris, E. Suna, J. Org. Chem. 1999, 64,
6724. For a recent report employing liquid ammonia
see: c) P. Ji, J. H. Atherton, M. I. Page, J. Org. Chem.
2012, 77, 7471.
introduced into a glovebox where dry and degassed DMF
(5 mL) and the aryl bromide (if liquid) were added. After
closing, the autoclave was charged out of the glovebox with
ammonia (1.7 g, 20 mmol, 20 equiv.) and the reaction mix-
ture was stirred for 24 h at 908C. The autoclave was allowed
to cool down to room temperature, then the ammonia was
released into the fume hood by opening the autoclave valve.
The autoclave was then opened and the reaction mixture
was filtered over celite. The conversion of the reaction was
determined by the appropriate analytical method and the
filtrate was concentrated under reduced pressure (20 mbar).
The crude product was purified by chromatography. Specific
procedures and characterization data are available in the
Supporting Information.
[9] a) J. Kim, S. Chang, Chem. Commun. 2008, 44, 3052;
b) K. G. Thakur, D. Ganapathy, G. Sekar, Chem.
Commun. 2011, 47, 5076.
[10] a) L. Jiang, X. Lu, H. Zhang, Y. Jiang, D. Ma, J. Org.
Chem. 2009, 74, 4542; b) J. Chen, T. Yuan, W. Hao, M.
Cai, Tetrahedron Lett. 2011, 52, 3710; c) B.-S. Liao, S.-
T. Liu, J. Org. Chem. 2012, 77, 6653; d) M. K. Elmkad-
dem, C. Fischmeister, C. M. Thomas, J.-L. Renaud,
Chem. Commun. 2010, 46, 925; e) N. Xia, M. Taillefer,
Angew. Chem. 2009, 121, 343; Angew. Chem. Int. Ed.
2009, 48, 337; f) Z. Wu, Z. Jiang, D. Wu, H. Xiang, X.
Zhou, Eur. J. Org. Chem. 2010, 1854; g) Y. Li, X. Zhu,
F. Meng, Y. Wan, Tetrahedron 2011, 67, 5450; h) D.
Wang, Q. Cai, K. Ding, Adv. Synth. Catal. 2009, 351,
1722; i) X. Zeng, W. Huang, Y. Qiu, S. Jiang, Org.
Biomol. Chem. 2011, 9, 8224.
Acknowledgements
We thank Dr. J. Schneider and the Analytical Services for
their support. The skilful experimental support of Ms. P.
Grijol, a student trainee from the University of Rennes,
France, is kindly acknowledged. We are grateful to Dr. S.
Ceccarelli and Dr. T. Schulz-Gasch for the cover design.
[11] In the broader context of cross-coupling reactions,
copper, owing to its low price and toxicity, has lately
emerged as an attractive alternative to palladium:
a) I. P. Beletskaya, A. V. Cheprakov, Coord. Chem.
Rev. 2004, 248, 2337; b) G. Evano, N. Blanchard, M.
Toumi, Chem. Rev. 2008, 108, 3054; c) F. Monnier, M.
Taillefer, Angew. Chem. 2009, 121, 7088; Angew. Chem.
Int. Ed. 2009, 48, 6954; d) D. S. Surry, S. L. Buchwald,
Chem. Sci. 2010, 1, 13.
References
[1] M. Appl, Ammonia, in: Ullmannꢀs Encyclopedia of In-
dustrial Chemistry, 7th ed. online 2012, Wiley, Wein-
heim.
[2] a) D. M. Roundhill, Chem. Rev. 1992, 92, 1. For the
recent development of mild methodology see: b) J. L.
Klinkenberg, J. F. Hartwig, Angew. Chem. 2011, 123,
88; Angew. Chem. Int. Ed. 2011, 50, 86; c) J. I. van
der Vlugt, Chem. Soc. Rev. 2010, 39, 2302.
[3] a) M. C. Willis, Angew. Chem. 2007, 119, 3470; Angew.
Chem. Int. Ed. 2007, 46, 3402; b) R. J. Lundgren, M.
Stradiotto, Chem. Eur. J. 2012, 18, 9758; c) S. Enthaler,
ChemSusChem 2010, 3, 1024.
[4] a) J. F. Hartwig, Synlett 2006, 9, 1283; b) M. Kienle,
S. R. Dubbaka, K. Brade, P. Knochel, Eur. J. Org.
Chem. 2007, 4166; c) D. S. Surry, S. L. Buchwald,
Angew. Chem. 2008, 120, 6438; Angew. Chem. Int. Ed.
2008, 47, 6338.
[12] We are fully aware that in some copper salts the coun-
ter anion can be regarded as a ligand. With the term
“ligandless” we define a system where no addition of
external ligand is required. See: a) C. Tao, W. Liu, A.
Lv, M. Sun, Y. Tian, Q. Wang, J. Zhao, Synlett 2010,
1355; b) M. S. Siddegowda, H. S. Yathirajan, R. A.
Ramakrishna, Tetrahedron Lett. 2012, 53, 5219; c) F.
Lang, D. Zewge, I. N. Houpis, R. P. Volante, Tetrahe-
dron Lett. 2001, 42, 3251; d) to the best of our knowl-
edge, an efficient ligandless system has been reported
by: H. Xu, C. Wolf, Chem. Commun. 2009, 3035; e) for
a mixed iron/copper system see: X.-F. Wu, C. Darcel,
Eur. J. Org. Chem. 2009, 4753.
[13] a) J. A. Joule, K. Mills, Heterocyclic Chemistry, 5th edn.,
Wiley, Chichester, 2010; b) A. Gomtsyan, Chem.
[5] a) C. Torborg, M. Beller, Adv. Synth. Catal. 2009, 351,
3027; b) J. S. Carey, D. Laffan, C. Thomson, M. T. Wil-
liams, Org. Biomol. Chem. 2006, 4, 2337.
HeteroACTHNUTRGENUGcN ycl. Compd. 2012, 48, 7; c) N. A. Meanwell, J.
630
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 627 – 631