Journal of the American Chemical Society
Article
decomposition or a mechanism for reaction with this catalyst
involving odd-electron nickel intermediates.
this detrimental path, and to determine if Ni(I) complexes are
generated during oxidative addition of haloarenes will be the
subject of future work.
CONCLUSIONS
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ASSOCIATED CONTENT
* Supporting Information
Detailed experimental procedure, characterizations of all
compounds, and crystallographic data (CIF) for compound 9.
This material is available free of charge via the Internet at
We have shown that nickel complexes containing common aryl
bisphosphine ligands can catalyze the coupling of aryl chlorides
and bromides with primary amines. In particular, we have
shown that the mixed Ni(0) species (BINAP)Ni(η2-NC-Ph)
containing one bisphosphine and one side-bound nitrile is a
particularly active catalyst for the coupling of chloroarenes with
primary amines and is more active than the related
(BINAP)2Ni catalyst. A range of electronically varied aryl
halides and nitrogen-containing heteroaryl chlorides, including
pyridine, quinoline, and isoquinoline derivatives, couple with a
variety of aliphatic primary amines in high isolated yields.
Several aspects of the current system lead to the ability of this
first-row metal system to catalyze this class of amination
reaction. In general, we attribute the high yields for these
amination reactions to the facile oxidative addition of aryl
chlorides and heteroaryl chlorides to the (BINAP)Ni(η2-NC-
Ph) precatalyst at ambient temperatures.
Detailed studies on the mechanism of the amination reaction
have been conducted. The following conclusions about the
mechanism of this coupling process have been drawn from
these studies:
(1) The oxidative addition of aryl chlorides to (BINAP)Ni-
(η2-NC-Ph), together with the stoichiometric reactions of
(BINAP)NiAr(Cl) with primary aliphatic amines in the
presence of base, support a reaction pathway involving a
Ni(0)/Ni(II) couple in the catalytic cycle.
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S
AUTHOR INFORMATION
Corresponding Author
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Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
The authors acknowledge the financial support of this work
from NIH (GM058108) and the Dow Chemical Company.
R.A.G. acknowledges NSERC and FQRNT for graduate
fellowships. The authors thank Dr. Antonio DiPasquale for
collecting the crystallographic data and solving the structure of
compound 9. We thank Jerzy Klosin at the Dow Chemical
Company for helpful discussions and critical reading of the
manuscript.
REFERENCES
■
(1) Ricci, A. Modern Amination Methods; Wiley-VCH Verlag GmbH:
Weinheim, 2000.
(2) Hartwig, J. F. Acc. Chem. Res. 2008, 41, 1534.
(3) Surry, D. S.; Buchwald, S. L. Angew. Chem., Int. Ed. 2008, 47,
6338.
(4) Ma, D.; Cai, Q. Acc. Chem. Res. 2008, 41, 1450.
(5) Hie, L.; Ramgren, S. D.; Mesganaw, T.; Garg, N. K. Org. Lett.
2012, 14, 4182.
(2) The oxidative addition of aryl chlorides and heteroaryl
chlorides to the single-component nickel precursor (BINAP)-
Ni(η2-NC-Ph) at ambient temperatures prevents the formation
of inactive Ni species.
(3) Ni(I) intermediates, which have been observed in
oxidative addition studies to phosphine-ligated Ni(0) com-
plexes, appear to result from decomposition of the Ni(II)
product of oxidative addition as opposed to forming from one-
electron pathways for oxidative addition to Ni(0).26
́
(6) Iglesias, M. J.; Blandez, J. F.; Fructos, M. R.; Prieto, A.; Alvarez,
E.; Belderrain, T. R.; Nicasio, M. C. Organometallics 2012, 31, 6312.
(7) Ilies, L.; Matsubara, T.; Nakamura, E. Org. Lett. 2012, 14, 5570.
(8) Kuhl, S.; Fort, Y.; Schneider, R. J. Organomet. Chem. 2005, 690,
6169.
(9) Martin, A. R.; Makida, Y.; Meiries, S.; Slawin, A. M. Z.; Nolan, S.
P. Organometallics 2013, 32, 6265.
(10) Mesganaw, T.; Garg, N. K. Org. Process Res. Dev. 2012, 17, 29.
(11) (a) Wolfe, J. P.; Buchwald, S. L. J. Am. Chem. Soc. 1997, 119,
6054. (b) Park, N. H.; Teverovskiy, G.; Buchwald, S. L. Org. Lett.
2014, 16, 220.
(12) Brenner, E.; Fort, Y. Tetrahedron Lett. 1998, 39, 5359.
(13) Brenner, E.; Schneider, R.; Fort, Y. Tetrahedron 1999, 55, 12829.
(14) Brenner, E.; Schneider, R.; Fort, Y. Tetrahedron Lett. 2000, 41,
2881.
(4) The reaction of (BINAP)Ni(η2-NC-Ph) with electron-
rich aryl chlorides, such as 4-chloroanisole, leads to the P−C
bond cleavage of the backbone of BINAP and forms the nickel
complex 9 containing two monophosphine ligands. The
formation of the catalytically inactive complex 9 explains the
high catalyst loading required for the amination of electron-rich
aryl chlorides.
(5) Mechanistic and kinetic studies revealed that the
turnover-limiting step of these nickel-catalyzed amination
reactions of aryl chlorides is oxidative addition of the aryl
chloride to (BINAP)Ni(0), which is formed by dissociation of
PhCN from the catalyst resting state (BINAP)Ni(η2-NC-Ph).
(6) Mechanistic and kinetic studies imply that the turnover-
limiting step of the reactions of aryl bromides is also oxidative
addition, but that aryl bromides react with a different nickel
species, of composition (BINAP)Ni(η2-NC-Ph) containing a
bound nitrile.
(7) The formation of catalytically inactive bis(amine)-ligated
Ni(II) species (RNH2)2NiAr(Cl), Ni(I) species [(BINAP)Ni-
(μ-Cl)]2, and bis-BINAP-ligated Ni(0) species (BINAP)2Ni are
the major pathways for catalyst inactivation.
Further studies to improve the lifetime of the Ni-
bisphosphine catalysts, to determine the mechanism by which
the phosphine-ligated Ni(I) species form as a means to prevent
(15) Desmarets, C.; Schneider, R.; Fort, Y. Tetrahedron Lett. 2000,
41, 2875.
(16) Desmarets, C.; Schneider, R.; Fort, Y. Tetrahedron Lett. 2001,
42, 247.
(17) Desmarets, C.; Schneider, R.; Fort, Y. J. Org. Chem. 2002, 67,
3029.
(18) Omar-Amrani, R.; Thomas, A.; Brenner, E.; Schneider, R.; Fort,
Y. Org. Lett. 2003, 5, 2311.
(19) Chen; Yang, L.-M. J. Org. Chem. 2007, 72, 6324.
(20) Gao, C.-Y.; Yang, L.-M. J. Org. Chem. 2008, 73, 1624.
(21) (a) Manolikakes, G.; Gavryushin, A.; Knochel, P. J. Org. Chem.
2008, 73, 1429. (b) Iglesias, M. J.; Prieto, A.; Nicasio, M. C. Adv.
Synth. Catal. 2010, 352, 1949. (c) Fan, X.-H.; Li, G.; Yang, L.-M. J.
Organomet. Chem. 2011, 696, 2482.
J
dx.doi.org/10.1021/ja411911s | J. Am. Chem. Soc. XXXX, XXX, XXX−XXX