Nickel-catalyzed monoarylation of ammonia

Article abstract of DOI:10.1002/anie.201410875

Structurally diverse (hetero)aryl chloride, bromide, and tosylate electrophiles were employed in the Ni-catalyzed monoarylation of ammonia, including chemoselective transformations. The employed JosiPhos/[Ni(cod)₂] catalyst system enables the use of commercially available stock solutions of ammonia, or the use of ammonia gas in these reactions, thereby demonstrating the versatility and potential scalability of the reported protocol. Proof-of-principle experiments established that air-stable [(JosiPhos)NiCl₂] precatalysts can be employed successfully in such transformations. Lighten Up: The substrate scope of the title reaction includes (hetero)aryl chloride, bromide, and tosylate electrophiles. The versatility and potential scalability of the reported method is demonstrated by the use of either commercially available stock solutions of ammonia or ammonia gas.

Full text of DOI:10.1002/anie.201410875

Angewandte
Chemie
DOI: 10.1002/anie.201410875
Ammonia Coupling
Hot Paper
Nickel-Catalyzed Monoarylation of Ammonia**
Andrey Borzenko, Nicolas L. Rotta-Loria, Preston M. MacQueen, Christopher M. Lavoie,
Robert McDonald, and Mark Stradiotto*
Abstract: Structurally diverse (hetero)aryl chloride, bromide,
and tosylate electrophiles were employed in the Ni-catalyzed
monoarylation of ammonia, including chemoselective trans-
formations. The employed JosiPhos/[Ni(cod)2] catalyst system
enables the use of commercially available stock solutions of
ammonia, or the use of ammonia gas in these reactions, thereby
demonstrating the versatility and potential scalability of the
reported protocol. Proof-of-principle experiments established
that air-stable [(JosiPhos)NiCl2] precatalysts can be employed
successfully in such transformations.
include catalyst deactivation arising from ammonia-induced
ancillary ligand dissociation, as well as uncontrolled polyar-
ylation arising as a result of the ability of the primary aniline
product to act as a contending substrate versus ammonia.[5]
Nonetheless, in 2006 Shen and Hartwig[7] demonstrated that
the judicious choice of the palladium source and the ancillary
ligand[8] can afford highly effective catalysts for ammonia
monoarylation. This observation and subsequent reports by
the groups of Hartwig,[9] Buchwald,[10] Beller,[11] and Stra-
diotto[12] on the employment of electron-rich and sterically
demanding phosphine ancillary ligands established broad
substrate scope in the (hetero)aryl (pseudo)halide reaction
partner (Figure 1a). The practical utility of the palladium-
catalyzed monoarylation of ammonia has recently been
demonstrated in the synthesis of pharmaceutically relevant
dibenzodiazepines,[10b] and in natural product synthesis.[13]
Ammonia ranks among the most widely produced commod-
ity chemicals, and virtually all synthetic nitrogen-containing
compounds originate from this inexpensive feedstock chem-
ical.[1] Notwithstanding the wide-ranging industrial-scale
processes that successfully utilize ammonia (e.g. the Ostwald
process[2] for nitric acid production), the industrial synthesis
of amines from ammonia often involves the use of heteroge-
neous catalysts at relatively high temperatures and pressures,
leading to poor product selectivity.
The application of homogeneous transition-metal catal-
ysis for the selective synthesis of amines from ammonia under
mild conditions is appealing, however, the development of
such transformations is challenging.[3] This is particularly true
for the palladium-catalyzed cross-coupling of (hetero)aryl
Figure 1. Previous reports of the monoarylation of ammonia catalyzed
by a) palladium and b) copper, and c) nickel-catalyzed transformations
reported herein.
À
(pseudo)halides with substrates containing N H groups (i.e.
Buchwald–Hartwig amination, BHA[4]). While BHA repre-
À
sents one of the most widely utilized C N bond-forming
protocols for the construction of (hetero)aromatic amines,
reports of the successful use of ammonia in such trans-
formations are exceedingly rare,[5] despite the fact that such
primary aniline derivatives represent sought-after synthetic
intermediates and target compounds in the construction of
both biologically active molecules and conjugated functional
organic materials.[6] Problems associated with the use of
ammonia in BHA and related cross-coupling reactions
Notwithstanding the utility of palladium-catalyzed ammo-
nia monoarylation protocols, the significant cost and rela-
tively low abundance of palladium led to the investigation of
first-row transition-metal catalysts for such difficult trans-
formations. Beyond economic benefits, the smaller size and
distinct electronic properties of the first-row transition metals,
relative to the platinum-group metals, may offer new
reactivity and thus a means of addressing outstanding
challenges in the monoarylation of ammonia. While copper
catalysts for ammonia monoarylation have been devel-
oped,[14] they exhibit a number of limitations, including poor
performance with (hetero)aryl chloride and phenol-derived
pseudohalide substrates (Figure 1b). Such limitations are
significant, as these substrates represent the least expensive
and most widely available aryl electrophile reaction partners.
In an alternative approach, we considered nickel-based
catalysts for use in the monoarylation of ammonia. Beyond
the fact that nickel is about 1000 times less expensive than
palladium, nickel is a privileged metal in myriad challenging
cross-coupling applications.[15] Indeed, nickel-based catalysts
have proven effective for the arylation of primary as well as
secondary amines in combination with synthetically useful
[*] Dr. A. Borzenko,[+] N. L. Rotta-Loria,[+] P. M. MacQueen,
C. M. Lavoie, Prof. Dr. M. Stradiotto
Department of Chemistry, Dalhousie University
Halifax, Nova Scotia B3H 4R2 (Canada)
E-mail: mark.stradiotto@dal.ca
Dr. R. McDonald
X-Ray Crystallography Laboratory
Department of Chemistry, University of Alberta
Edmonton, Alberta T6G 2G2 (Canada)
[+] These authors contributed equally to this work.
[**] We thank NSERC of Canada, the Killam Trusts, and Dalhousie
University for their generous support of this work. We also thank
Solvias for the gift of some of the ligands used in this study.
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201410875.
Angew. Chem. Int. Ed. 2015, 54, 1 – 6
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
These are not the final page numbers!

.
Angewandte
Communications
(hetero)aryl chlorides and phenol-derived pseudohalide (het-
ero)aryl electrophiles.[15a,16] However, despite this significant
nia, including Mor-DalPhos,[12a] BippyPhos,[12d] and the Josi-
Phos ligand variant CyPF-tBu.[7,9] While none were found to
be particularly selective for ammonia monoarylation, the
modest success achieved with CyPF-tBu prompted a more
detailed survey of structurally related JosiPhos (L1–L9),
TaniaPhos (L10 and L11), and WalPhos (L12 and L13) ligands
developed by Solvias. Gratifyingly, ligands L7–L10 proved
highly effective, affording high conversion to 4-aminobi-
phenyl (1), which was isolated in 82% yield using L9. We are
presently unable to rationalize the success of L7–L10, both in
terms of the structural variability found within this successful
set of ligands, and between these and structurally similar yet
less effective ferrocenyl ligands within the screened set.
Nonetheless, we subsequently observed that L9 was modestly
more effective than L7, L8, or L10 in a small selection of
nickel-catalyzed ammonia monoarylation reactions involving
alternative (hetero)aryl halide electrophiles. We thus used L9
as the ligand of choice in exploring the scope of reactivity with
various (hetero)aryl (pseudo)halides more broadly. Given
À
progress in C N cross-coupling chemistry, effective nickel-
based catalysts for the monoarylation of the most ubiquitous
À
and important N H reagent, ammonia, were unknown prior
to our work reported herein.
A particularly attractive feature of nickel catalysis,
relative to palladium catalysis, is the often successful employ-
ment of structurally simple ancillary ligands.[15a] However,
lacking prior reports of effective nickel-based catalysts for the
monoarylation of ammonia, we screened ligands for the cross-
coupling of 4-bromobiphenyl and ammonia to afford 4-
aminobiphenyl (1), using a range of structurally complex
phosphine-based ancillary ligands (Figure 2). For simplicity,
À
recent evidence for photoinduced Ullmann C N coupling
involving copper-based catalysts,[18] we conducted control
experiments employing L9 in the nickel-catalyzed monoar-
ylation of ammonia with 4-bromobiphenyl with the exclusion
of ambient light. No change in catalytic performance was
noted relative to reactions conducted without such precau-
tions.
Having identified an effective nickel-based catalyst
system for the monoarylation of ammonia, we turned our
attention to exploring the scope of reactivity (Figure 3).
Preliminary studies confirmed that L9/[Ni(cod)2] can accom-
modate analogous chloride and tosylate electrophiles, afford-
ing 1 in 88% and 90% yield, respectively. A selection of para-
substituted 4-chlorobiphenyl derivatives featuring methyl,
cyano, trifluoromethyl, or methoxy substituents were also
accommodated (2–5, 72–92%), as were structurally related
pyrrole (6, 78%) and pyridine (7, 81%) substrates. Chlor-
obenzenes featuring one or two substituents in the ortho
position, or alternatively fluoro or methoxy substituents,
proved to be compatible substrates (8–12, 71–85%). We also
challenged the L9/[Ni(cod)2] catalyst system with chloroben-
zene substrates featuring potentially competitive secondary
amine functionalities, and observed chemoselectivity for
ammonia monoarylation, affording 13 (68%) and 14 (75%).
The success of the L9/[Ni(cod)2] catalyst system in the
monoarylation of ammonia is noteworthy, as no first-row
transition-metal catalyst, including the various copper-based
catalysts reported to date,[14] was able to promote the cross-
coupling of ammonia with unactivated aryl chlorides, or
tosylate electrophiles.
Heteroaryl primary aniline derivatives represent partic-
ularly attractive synthons in medicinal, biological, natural
products and materials chemistry.[6] Therefore, we expanded
our studies on the substrate scope to various heteroaryl
chlorides and bromides (Figure 3). Remarkably, amino-func-
tionalized pyridine (15), pyrimidine (16), quinaldine (17, 18),
isoquinoline (19), quinoline (20, 21), quinoxaline (22, 23),
benzothiophene (24), and benzothiazole (25) heterocycles
were prepared efficiently by using our nickel-catalyzed
ammonia monoarylation protocol (Figure 3, 68–85%). Only
Figure 2. Ligand screen for the nickel-catalyzed monoarylation of
ammonia with 4-bromobiphenyl using 0.5m stock solutions of ammo-
nia in 1,4-dioxane. Conversion determined by GC, reported as % 4-
aminobiphenyl (% biphenyl); mass balance attributable to remaining
4-bromobiphenyl and/or unidentified side products.
we intentionally screened catalysts that did not require added
nitrile as a co-ligand[16w] or additive,[16y] and employed
commercially available ammonia stock solutions (0.5m in
1,4-dioxane). Our choice of an aryl bromide in this screening
process, rather than more sought-after chloride aryl electro-
philes, was based on the apparently more challenging nature
À
of aryl bromides in nickel-catalyzed C N cross-coupling
reactions.[17] We initially focussed our attention on the use of
rac-BINAP and DPPF, given the successful application of
À
nickel catalysts featuring these ligands in C N cross-couplings
of both primary and secondary amines.[16a,w,y] However, these
ligands, as well as the more electron-rich DiPPF, proved
ineffective for the nickel-catalyzed selective monoarylation of
ammonia under the screening conditions employed. We then
turned our attention to the application of a selection of other
commercially available ancillary ligands that have proven
effective in the palladium-catalyzed monoarylation of ammo-
2
www.angewandte.org
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2015, 54, 1 – 6
These are not the final page numbers!

Angewandte
Chemie
The air- and moisture-sensitive nature of [Ni(cod)2]
prompted us to develop air-stable nickel precatalysts for use
in ammonia monoarylation. In a preliminary effort in this
regard, we examined the reaction of [NiCl2(dme)] with L8
and L9 (Figure 4a). Both reactions were successful and
Figure 4. a) Synthesis of the air-stable (JosiPhos)NiCl2 precatalyst
complexes C1 and C2, and single-crystal X-ray structure of C1 (30%
ellipsoids; selected hydrogen atoms omitted). b) Successful applica-
tion of C2 in the synthesis of 24.
Figure 3. Scope of Ni-catalyzed monoarylation of ammonia with (heter-
o)aryl (pseudo)halides (yields of isolated products reported). Unless
stated otherwise, ammonia was obtained from 0.5m 1,4-dioxane stock
solutions. [a] Ammonia gas employed under similar conditions
(114 psi initial pressure, see the Supporting Information for full
details). [b] Yield of the corresponding isolated (aryl)NHTs. [c] 7 equiv
NH3. [d] 658C. [e] 5 equiv NH3. [f] Using L8.
afforded analytically pure and air-stable [(L8)NiCl2·THF]
(C1, 87%) and [(L9)NiCl2] (C2, 66%). The established
propensity of [(PR3)2NiCl2] complexes to exist as equilibrium
mixtures of tetrahedral (paramagnetic) and square-planar
(diamagnetic) isomers,[19] was confirmed by solution NMR
data obtained for C1 and C2, revealing significant para-
magnetic broadening at 300 K. However, single-crystal X-ray
diffraction analysis of C1·2.5C6H6 confirmed the bidentate
connectivity in C1 within a distorted square-planar coordina-
tion geometry at the nickel center (Figure 4a).[20] Gratifyingly,
in a proof-of-principle transformation employing air-stable
C2 as a precatalyst (with PhBPin as the reductant), 5-
chlorobenzothiophene was selectively transformed into the
aniline derivative 24 (63% yield, Figure 4b).
In summary, we have identified a JosiPhos/[Ni(cod)2]
catalyst system that has enabled the first examples of
ammonia monoarylation chemistry employing nickel cataly-
sis. In such cross-coupling chemistry, structurally diverse
(hetero)aryl chloride, bromide, and tosylate electrophiles
featuring a range of functionalities (e.g. methoxy, cyano,
fluoro, trifluoromethyl, pyrrolyl, pyridyl) and heteroaryl
motifs (e.g. pyridine, pyrimidine, quinaldine, isoquinoline,
quinoline, quinoxaline, benzothiophene, benzothiazole) were
successfully accommodated, as were substrates featuring
in the case of 6-chloroquinoline, leading to 21, did we observe
that the performance of L9 was inferior to that of L8. Control
experiments involving the formation of 15, 16, and 22 in the
absence of L9/[Ni(cod)2] showed no conversion to the desired
product.
In the experiments described thus far, we used commer-
cially available 0.5m solutions of ammonia in 1,4-dioxane,
which is apparently the protocol of choice in analogous
palladium-catalyzed reactions.[9–13] While convenient and
operationally simple for use in small-scale laboratory synthe-
ses, the use of ammonia gas would appear to be more scalable.
Notwithstanding the significant progress that has been
achieved in the development of effective palladium catalysts
for the monoarylation of ammonia, to the best of our
knowledge the use of ammonia gas in such transformations
is limited to only two reports by the Hartwig group.[7,9] While
the particular reason for this trend is unclear, it is possible that
catalyst deactivation arising from ammonia-induced ancillary
ligand dissociation may be problematic for some catalyst
systems under high pressures of ammonia.[5] Gratifyingly, the
L9/[Ni(cod)2] catalyst system performed well in selected test
reactions employing ammonia gas (114 psi initial pressure),
affording the desired (hetero)biaryl (1, 94%; 5, 80%; 6,
69%), quinaldine (18, 92%), and benzothiophene (24, 85%)
derivatives in high yields that are competitive with those
obtained when using 0.5m solutions of ammonia in 1,4-
dioxane (Figure 3).
À
potentially competitive N H functionalities. Such broad
reaction scope, when coupled with the demonstrated efficacy
of the reported JosiPhos/[Ni(cod)2] catalyst system when
using either commercially available stock solutions of ammo-
nia or ammonia gas, serves to underscore the versatility and
potential scalability of the reported protocol. Proof-of-
principle experiments established that air-stable (JosiPhos)-
NiCl2 precatalysts can also be employed with success in such
Angew. Chem. Int. Ed. 2015, 54, 1 – 6
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3
These are not the final page numbers!

.
Angewandte
Communications
[13] P. N. Carlsen, T. J. Mann, A. H. Hoveyda, A. J. Frontier, Angew.
Chem. Int. Ed. 2014, 53, 9334 – 9338; Angew. Chem. 2014, 126,
9488 – 9492.
challenging transformations. The scope of the nickel-cata-
lyzed ammonia monoarylation reactions reported herein is
unprecedented in first-row transition-metal catalysis. Indeed,
while not exhaustively demonstrated, the results presented
herein establish for the first time the viability of nickel
catalysts functioning as first-row competitors to state-of-the-
art palladium catalysts, with regard to substrate scope in
ammonia monoarylation chemistry. Future work will focus on
exploring the mechanism of the transformations reported
herein, as well as on applying this and other nickel-based
catalysts in addressing challenging cross-coupling chemistry
that is traditionally dominated by palladium catalysis.
[14] a) F. R. Lang, D. Zewge, I. N. Houpis, R. P. Volante, Tetrahedron
Lett. 2001, 42, 3251 – 3254; b) J. Kim, S. Chang, Chem. Commun.
2008, 3052 – 3054; c) D. P. Wang, Q. Cai, K. Ding, Adv. Synth.
Catal. 2009, 351, 1722 – 1726; d) X. F. Wu, C. Darcel, Eur. J. Org.
Chem. 2009, 4753 – 4756; e) N. Xia, M. Taillefer, Angew. Chem.
Int. Ed. 2009, 48, 337 – 339; Angew. Chem. 2009, 121, 343 – 345;
f) H. H. Xu, C. Wolf, Chem. Commun. 2009, 3035 – 3037; g) Z. Q.
Wu, Z. Q. Jiang, D. Wu, H. F. Xiang, X. G. Zhou, Eur. J. Org.
Chem. 2010, 1854 – 1857; h) J. Jiao, X. R. Zhang, N. H. Chang, J.
Wang, J. F. Wei, X. Y. Shi, Z. G. Chen, J. Org. Chem. 2011, 76,
1180 – 1183; i) K. G. Thakur, D. Ganapathy, G. Sekar, Chem.
Commun. 2011, 47, 5076 – 5078; j) H. Wang, Y. Li, L. Jiang, R.
Zhang, K. Jin, D. Zhao, C. Duan, Org. Biomol. Chem. 2011, 9,
4983 – 4986; k) P. Ji, J. H. Atherton, M. I. Page, J. Org. Chem.
2012, 77, 7471 – 7478; l) B. S. Liao, S. T. Liu, J. Org. Chem. 2012,
77, 6653 – 6656; m) S. Guo, J. Wang, X. Fan, X. Zhang, D. Guo, J.
Org. Chem. 2013, 78, 3262 – 3270.
Received: November 8, 2014
Published online: && &&, &&&&
Keywords: amination · ammonia · arylation · cross-coupling ·
.
nickel
[15] a) B. M. Rosen, K. W. Quasdorf, D. A. Wilson, N. Zhang, A. M.
Resmerita, N. K. Garg, V. Percec, Chem. Rev. 2011, 111, 1346 –
1416; b) T. Mesganaw, N. K. Garg, Org. Process Res. Dev. 2013,
17, 29 – 39; c) S. Z. Tasker, E. A. Standley, T. F. Jamison, Nature
2014, 509, 299 – 309.
[1] M. Appl, Ammonia: Principles and Industrial Practice, Wiley-
VCH, Weinheim, 1999.
[2] F. C. Zeisberg, Chem. Metall. Eng. 1916, 15, 299 – 304.
[3] a) Y. Aubin, C. Fischmeister, C. M. Thomas, J. L. Renaud, Chem.
Soc. Rev. 2010, 39, 4130 – 4145; b) J. I. van der Vlugt, Chem. Soc.
Rev. 2010, 39, 2302 – 2322; c) J. L. Klinkenberg, J. F. Hartwig,
Angew. Chem. Int. Ed. 2011, 50, 86 – 95; Angew. Chem. 2011, 123,
88 – 98; d) J. Kim, H. J. Kim, S. Chang, Eur. J. Org. Chem. 2013,
3201 – 3213.
[4] a) A. S. Guram, R. A. Rennels, S. L. Buchwald, Angew. Chem.
Int. Ed. Engl. 1995, 34, 1348 – 1350; Angew. Chem. 1995, 107,
1456 – 1459; b) J. Louie, J. F. Hartwig, Tetrahedron Lett. 1995, 36,
3609 – 3612; c) J. F. Hartwig, Acc. Chem. Res. 2008, 41, 1534 –
1544; d) D. S. Surry, S. L. Buchwald, Angew. Chem. Int. Ed. 2008,
47, 6338 – 6361; Angew. Chem. 2008, 120, 6438 – 6461.
[5] M. Stradiotto, in New Trends in Cross-Coupling: Theory and
Application (Ed.: T. J. Colacot), Royal Society of Chemistry,
Cambridge, 2014, pp. 228 – 253.
[6] a) M. Liang, J. Chen, Chem. Soc. Rev. 2013, 42, 3453 – 3488;
b) S. A. Lawrence, Amines: Synthesis Properties and Applica-
tions, Cambridge University Press, Cambridge, 2006; c) A. G.
MacDiarmid, Angew. Chem. Int. Ed. 2001, 40, 2581 – 2590;
Angew. Chem. 2001, 113, 2649 – 2659.
[7] Q. L. Shen, J. F. Hartwig, J. Am. Chem. Soc. 2006, 128, 10028 –
10029.
[8] R. J. Lundgren, M. Stradiotto, Chem. Eur. J. 2012, 18, 9758 –
9769.
[16] a) J. P. Wolfe, S. L. Buchwald, J. Am. Chem. Soc. 1997, 119,
6054 – 6058; b) E. Brenner, R. Schneider, Y. Fort, Tetrahedron
Lett. 2000, 41, 2881 – 2884; c) C. Desmarets, R. Schneider, Y.
Fort, Tetrahedron Lett. 2000, 41, 2875 – 2879; d) B. H. Lipshutz,
H. Ueda, Angew. Chem. Int. Ed. 2000, 39, 4492 – 4494; Angew.
Chem. 2000, 112, 4666 – 4668; e) C. Desmarets, R. Schneider, Y.
Fort, Tetrahedron Lett. 2001, 42, 247 – 250; f) R. Omar-Amrani,
A. Thomas, E. Brenner, R. Schneider, Y. Fort, Org. Lett. 2003, 5,
2311 – 2314; g) R. A. Kelly III, N. M. Scott, S. Diez-Gonzalez,
E. D. Stevens, S. P. Nolan, Organometallics 2005, 24, 3442 – 3447;
h) C. Chen, L.-M. Yang, J. Org. Chem. 2007, 72, 6324 – 6327; i) K.
Matsubara, K. Ueno, Y. Koga, K. Hara, J. Org. Chem. 2007, 72,
5069 – 5076; j) G. Manolikakes, A. Gavryushin, P. Knochel, J.
Org. Chem. 2008, 73, 1429 – 1434; k) C.-Y. Gao, X. Cao, L.-M.
Yang, Org. Biomol. Chem. 2009, 7, 3922 – 3925; l) M. Tobisu, T.
Shimasaki, N. Chatani, Chem. Lett. 2009, 38, 710 – 711; m) L.
Ackermann, W. Song, R. Sandmann, J. Organomet. Chem. 2011,
696, 195 – 201; n) T. Shimasaki, M. Tobisu, N. Chatani, Angew.
Chem. Int. Ed. 2010, 49, 2929 – 2932; Angew. Chem. 2010, 122,
2991 – 2994; o) L. Ackermann, R. Sandmann, W. Song, Org. Lett.
2011, 13, 1784 – 1786; p) J.-H. Huang, L.-M. Yang, Org. Lett.
2011, 13, 3750 – 3753; q) T. Mesganaw, A. L. Silberstein, S. D.
Ramgren, N. F. F. Nathel, X. Hong, P. Liu, N. K. Garg, Chem.
Sci. 2011, 2, 1766 – 1771; r) S. D. Ramgren, A. L. Silberstein, Y.
Yang, N. K. Garg, Angew. Chem. Int. Ed. 2011, 50, 2171 – 2173;
Angew. Chem. 2011, 123, 2219 – 2221; s) L. Hie, S. D. Ramgren,
T. Mesganaw, N. K. Garg, Org. Lett. 2012, 14, 4182 – 4185;
t) M. J. Iglesias, J. F. Blandez, M. R. Fructos, A. Prieto, E.
Alvarez, T. R. Belderrain, M. C. Nicasio, Organometallics 2012,
31, 6312 – 6316; u) M. Tobisu, A. Yasutome, K. Yamakawa, T.
Shimasaki, N. Chatani, Tetrahedron 2012, 68, 5157 – 5161;
v) A. R. Martin, Y. Makida, S. Meiries, A. M. Z. Slawin, S. P.
Nolan, Organometallics 2013, 32, 6265 – 6270; w) S. Ge, R. A.
Green, J. F. Hartwig, J. Am. Chem. Soc. 2014, 136, 1617 – 1627;
x) N. F. Fine Nathel, J. Kim, L. N. Hie, X. Y. Jiang, N. K. Garg,
ACS Catal. 2014, 4, 3289 – 3293; y) N. H. Park, G. Teverovskiy,
S. L. Buchwald, Org. Lett. 2014, 16, 220 – 223; z) S. S. Kamp-
mann, A. N. Sobolev, G. A. Koutsantonis, S. G. Stewart, Adv.
Synth. Catal. 2014, 356, 1967 – 1973.
[9] G. D. Vo, J. F. Hartwig, J. Am. Chem. Soc. 2009, 131, 11049 –
11061.
[10] a) D. S. Surry, S. L. Buchwald, J. Am. Chem. Soc. 2007, 129,
10354 – 10355; b) D. Tsvelikhovsky, S. L. Buchwald, J. Am.
Chem. Soc. 2011, 133, 14228 – 14231; c) C. W. Cheung, D. S.
Surry, S. L. Buchwald, Org. Lett. 2013, 15, 3734 – 3737.
[11] a) T. Schulz, C. Torborg, S. Enthaler, B. Schaffner, A. Dumrath,
A. Spannenberg, H. Neumann, A. Borner, M. Beller, Chem. Eur.
J. 2009, 15, 4528 – 4533; b) A. Dumrath, C. Lubbe, H. Neumann,
R. Jackstell, M. Beller, Chem. Eur. J. 2011, 17, 9599 – 9604.
[12] a) R. J. Lundgren, B. D. Peters, P. G. Alsabeh, M. Stradiotto,
Angew. Chem. Int. Ed. 2010, 49, 4071 – 4074; Angew. Chem.
2010, 122, 4165 – 4168; b) P. G. Alsabeh, R. J. Lundgren, L. E.
Longobardi, M. Stradiotto, Chem. Commun. 2011, 47, 6936 –
6938; c) P. G. Alsabeh, R. J. Lundgren, R. McDonald,
C. C. C. J. Seechurn, T. J. Colacot, M. Stradiotto, Chem. Eur. J.
2013, 19, 2131 – 2141; d) S. M. Crawford, C. B. Lavery, M.
Stradiotto, Chem. Eur. J. 2013, 19, 16760 – 16771.
[17] For selected recent examples that demonstrate this trend, see
references [16w,x].
4
www.angewandte.org
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2015, 54, 1 – 6
These are not the final page numbers!

Angewandte
Chemie
[18] S. E. Creutz, K. J. Lotito, G. C. Fu, J. C. Peters, Science 2012, 338,
647 – 651.
Sutton, J. Chem. Soc. 1962, 693 – 703; d) G. Garton, D. E. Henn,
L. M. Venanzi, H. M. Powell, J. Chem. Soc. 1963, 3625 – 3629.
[20] CCDC 1028684 contains the supplementary crystallographic
data for C1·2.5C6H6. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif. Additional details of the
solution and refinement process for C1·2.5C6H6 are provided in
the Supporting Information.
[19] a) M. C. Browning, D. J. Morgan, L. E. Sutton, L. M. Venanzi,
R. F. B. Davies, J. Chem. Soc. 1961, 4816 – 4823; b) C. Couss-
maker, M. H. Hutchinson, L. E. Sutton, J. R. Mellor, L. M.
Venanzi, J. Chem. Soc. 1961, 2705 – 2713; c) M. C. Browning,
L. M. Venanzi, D. J. Morgan, J. R. Mellor, S. A. J. Pratt, L. E.
Angew. Chem. Int. Ed. 2015, 54, 1 – 6
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
5
These are not the final page numbers!

.
Angewandte
Communications
Communications
Ammonia Coupling
A. Borzenko, N. L. Rotta-Loria,
P. M. MacQueen, C. M. Lavoie,
R. McDonald,
M. Stradiotto*
&&& — &&&
Nickel-Catalyzed Monoarylation of
Ammonia
Lighten Up: The substrate scope of the
title reaction includes (hetero)aryl chlo-
ride, bromide, and tosylate electrophiles.
The versatility and potential scalability of
the reported protocol is demonstrated by
the use of either commercially available
stock solutions of ammonia or ammonia
gas.
6
www.angewandte.org
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2015, 54, 1 – 6
These are not the final page numbers!