IrIII-catalyzed direct C-7 amidation of indolines with sulfonyl, acyl, and aryl azides at room temperature

Article abstract of DOI:10.1002/ejoc.201403355

A general procedure for an Ir^III-catalyzed C-7 selective C-H amidation and amination of indolines is reported. The reaction exhibits good functional group tolerance, requires no external oxidants, and releases N₂ as the single byproduct, thus providing an environmentally benign, readily scalable method for the synthesis of 7-aminoindolines. More importantly, acyl, sulfonyl, and aryl azides can be employed as the amino source in this C-H amidation reaction under very mild and pH-neutral reaction conditions (i.e., room temperature) to afford N-(7-indolinyl)amides, N-(7indolinyl)-sulfonamides, and N-(7-indolinyl)arylamines in good to excellent yields. In addition, a one-pot synthesis for 7-aminoindoles was developed. Overall, this procedure is robust, reliable, and compatible in air.

Full text of DOI:10.1002/ejoc.201403355

FULL PAPER
DOI: 10.1002/ejoc.201403355
IrIII-Catalyzed Direct C-7 Amidation of Indolines with Sulfonyl, Acyl, and
Aryl Azides at Room Temperature
Wei Hou,[a] Yaxi Yang,[a] Wen Ai,[b] Yunxiang Wu,[a] Xuan Wang,[a] Bing Zhou,*[a] and
Yuanchao Li*[a]
Keywords: Nitrogen heterocycles / C–H activation / Iridium / Regioselectivity / Amidation
A general procedure for an IrIII-catalyzed C-7 selective C–H
amidation and amination of indolines is reported. The reac-
tion exhibits good functional group tolerance, requires no ex-
ternal oxidants, and releases N2 as the single byproduct, thus
providing an environmentally benign, readily scalable
method for the synthesis of 7-aminoindolines. More import-
antly, acyl, sulfonyl, and aryl azides can be employed as the
amino source in this C–H amidation reaction under very mild
and pH-neutral reaction conditions (i.e., room temperature)
to afford N-(7-indolinyl)amides, N-(7indolinyl)-sulfonamides,
and N-(7-indolinyl)arylamines in good to excellent yields. In
addition, a one-pot synthesis for 7-aminoindoles was devel-
oped. Overall, this procedure is robust, reliable, and com-
patible in air.
Introduction
Indoles are of great interest in organic synthesis because
of their presence in numerous natural products, pharmaceu-
ticals, and agrochemicals.[1] Among them, 7-substituted ind-
oles are particularly important as a result of their ubiqui-
tous presence in numerous biologically active compounds
(see Figure 1).[2] Therefore, a method for a general, rapid,
and regioselective preparation of 7-substituted indoles
would be highly desirable.
Recently, transition-metal-catalyzed C–H bond acti-
vations have become an increasingly viable tool for direct
C–H bond functionalizations, as this process removes the
need for the tedious prefunctionalization of the substrate,
thus enhancing the overall scope and efficiency.[3] Given the
significance of 7-substituted indoles, it would be highly de-
sirable and attractive if we could directly functionalize the
C–H bond at the C-7 position of an indole by using a tran-
sition-metal-catalyzed C–H activation pathway. Although
considerable studies of transition-metal-catalyzed C–H
bond functionalizations at the C-2 and C-3 positions of ind-
ole have been carried out over the past decades,[4] there are
few reports of a C-7 selective C–H bond functionalization
of indole.[5,6] Moreover, these approaches are generally lim-
Figure 1. Representative biologically active compounds that con-
tain the 7-aminoindole structural motif.
ited to C–C bond formation,[5] and only one example that
involves the construction of a C–N bond has been reported,
thus proving it to be a formidable challenge (see Scheme 1,
a).[6] Despite this great breakthrough, this approach still has
some constraints, such as a limited substrate scope, a high
reaction temperature, and the need for 0.5 equiv. of AgOAc.
Therefore, it is of utmost importance to develop a new
method for the efficient construction of biologically impor-
tant 7-aminoindoles.[1,2]
Along with our continuous efforts towards the regioselec-
tive C–H functionalization of indoles[4l,4o] and transition-
metal-catalyzed C–H amidation reactions,[7b,7e] we herein
report a general approach under air for the amidation of
[a] Department of Medicinal Chemistry, Shanghai Institute of
Materia Medica, Chinese Academy of Sciences,
555 Zu Chong Zhi Road, Shanghai 201203, P. R. China
E-mail: zhoubing2012@hotmail.com
ycli@mail.shcnc.ac.cn
http://english.simm.cas.cn/
[b] Key Lab for Advanced Materials and Institute of Fine
Chemicals, East China University of Science and Technology,
130 Meilong Road, Shanghai 200237, P. R. China
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201403355.
Eur. J. Org. Chem. 2015, 395–400
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
395

W. Hou, Y. Yang, W. Ai, Y. Wu, X. Wang, B. Zhou, Y. Li
FULL PAPER
Scheme 1. C-7 amidation of indolines (DCE = 1,2-dichloroethane, Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl, Tf = trifluoromethylsul-
fonyl).
the C–H bond at the C-7 position of indoline by employing Table 1. Optimization of direct C–H amidation at C-7 of indol-
ines.[a]
an iridium-catalyzed C–H bond activation (see Scheme 1,
b). This reaction tolerates various synthetically important
functional groups, requires no external oxidants, and re-
leases benign N2 as the only byproduct. Significantly, acyl,
sulfonyl, and aryl azides can be employed as the amino
source in this C–H amidation reaction to afford N-(7-
indolinyl)amides, N-(7-indolinyl)sulfonamides, and N-(7-
indolinyl)arylamines, respectively, in good to excellent
yields under very mild and neutral reaction conditions (i.e.,
at room temperature).
Entry Catalyst
Solvent
Yield [%][b]
1
[Cp*Rh (CH3CN)3](SbF6)2
DCE
DCE
DCE
DCE
DCE
THF[c]
PhMe
DCE
0
0
2
3
4
5
(RhCp*Cl2)2/AgSbF6
[RuCl2(p-cymene)]2/AgSbF6
(IrCp*Cl2)2/AgSbF6
(IrCp*Cl2)2/AgNTf2
(IrCp*Cl2)2/AgNTf2
(IrCp*Cl2)2/AgNTf2
(IrCp*Cl2)2/AgNTf2
13
80
90
30
40
90
6
7
Results and Discussion
8[d]
N-Acetylindoline (1a) and tosyl azide (2a) were chosen
as the model substrates (see Table 1). First, the reaction was
catalyzed by using known reaction conditions {prepared
RhIII precursor [Cp*Rh(CH3CN)3](SbF6)2 (2.5 mol-%) in
DCE at 80 °C; see Table 1, Entry 1).[7] Unfortunately, no
conversion occurred. The employment of a cationic RhIII
species, which was generated in situ by treating (RhCp*Cl2)2
with AgSbF6, was also an ineffective catalyst for this C–H
[a] Reagents and conditions: 1a (0.2 mmol), 2a (0.22 mmol), cata-
lyst (0.005 mmol, 2.5 mol-%), and solvent (1 mL) at 80 °C for 1 h.
[b] Yield of isolated product. [c] THF = tetrahydrofuran. [d] The
reaction was carried out at room temperature for 3 h.
With an optimized catalytic system in hand, we examined
amidation reaction (see Table 1, Entry 2). Next, other cata- the scope of the sulfonyl azides (see Scheme 2). To our de-
lysts were screened. [RuCl2(p-cymene)]2 (2.5 mol-%), with light, the arenesulfonyl azides that contained either elec-
AgSbF6 (10 mol-%) gave the desired product 3a in 13% tron-donating (i.e., 3a and 3b) or electron-withdrawing
yield (see Table 1, Entry 3). Surprisingly, when the reaction groups (i.e., 3c) were well tolerated and gave the corre-
was treated with (IrCp*Cl2)2 (2.5 mol-%) and AgSbF6 sponding products in Ͼ90% yield. The large naphthalene-
(10 mol-%), a dramatic increase in the reaction yield (80%) 2-sulfonyl azide also readily participated in the amidation
was observed (see Table 1, Entry 4). Moreover, using reaction to provide product 3d in 94% yield. Furthermore,
AgNTf2, a different halide abstractor, further improved the good yields were obtained when heteroaromatic (i.e., 3e)
yield (see Table 1, Entry 5). When other organic solvents and alkylsulfonyl azides (i.e., 3f) were used in the reaction,
were used, the yield decreased, and thus DCE proved to be which demonstrated the generality of this method.
the optimal solvent for the reaction (see Table 1, Entries 5–
Encouraged by the successful results of the amidation
7). Notably, this reaction could be carried out at room tem- with sulfonyl azides, we turned our attention to acyl azides
perature without a decrease in the yield (see Table 1, En- (see Scheme 3). In contrast to previous results,[8] we were
try 8).
396
pleased to find that acyl azides also worked well to facilitate
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 395–400

IrIII-Catalyzed Direct C-7 Amidation of Indolines
In addition to sulfonyl and acyl azides, the scope of the
reaction with aryl azide substrates was also explored (see
Scheme 4). To our delight, aryl azides that contained elec-
Scheme 2. Ir-catalyzed C-7 amidation of indolines with sulfonyl az-
ides. Reagents and conditions: 1a (0.2 mmol), 2 (0.22 mmol),
(IrCp*Cl2)2 (2.5 mol-%), AgNTf2 (10 mol-%), and DCE (1 mL) at
room temperature for 3 h. The yield of the isolated product is pro-
vided.
the direct amidation of indolines at room temperature.
Benzoyl azides that contained electron-withdrawing (i.e.,
5b–5f), electron-neutral (i.e., 5a), or electron-donating sub-
stituents (i.e., 5g and 5h) at the para (i.e., 5b–5d, 5g, and
5h), ortho (i.e., 5e), or meta (i.e., 5f) position were tolerated
in this amidation reaction to give the corresponding prod-
ucts in good yields.
Scheme 4. Substrate scope for aryl azides. Reagents and conditions:
1 (0.2 mmol), 6 (0.24 mmol), (IrCp*Cl2)2 (2.5 mol-%), AgNTf2
(10 mol-%), and DCE (1 mL) at room temperature for 6 h. The
yield of the isolated product is provided.
Scheme 3. Ir-catalyzed C-7 amidation of indolines with acyl azides. Reagents and conditions: 1a (0.2 mmol), 4 (0.22 mmol), (IrCp*Cl2)2
(2.5 mol-%), AgNTf2 (10 mol-%), and DCE (1 mL) at room temperature for 6 h. The yield of isolated product is provided. [a] The reaction
was carried out at 50 °C for 6 h.
Eur. J. Org. Chem. 2015, 395–400
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
397

W. Hou, Y. Yang, W. Ai, Y. Wu, X. Wang, B. Zhou, Y. Li
FULL PAPER
tron-withdrawing (i.e., 7a–7e and 7g–7i) or electron-donat-
ing substituents (i.e., 7f) at the para (i.e., 7a–7f) or meta (i.e.,
7g–7i) position were tolerated in this amidation reaction to
afford the corresponding products in moderate to excellent
yields.
Next, we surveyed the substrate scope of the reaction of
various indolines with sulfonyl azides (see Scheme 5). To
our delight, indolines that contained electron-withdrawing
(i.e., 3g, 3h, and 3o) or electron-donating groups (i.e., 3i–
3m) at the C-2, C-3, C-4, C-5, or C-6 position of the
indoline ring were tolerated in this reaction to afford the
corresponding amidation product in 80–99% yield. No-
tably, halo and ester substituents, which can provide oppor-
tunities for further transformations, were tolerated. In ad-
dition, N,N-disubstituted carbamoylindolines were also suc-
cessfully employed in this reaction to yield product 3p and
3q in 60 and 65% yield, respectively.
(1)
(2)
(3)
(4)
To gain insight into the mechanism, the following experi-
ments were performed. When 1a was treated with a catalytic
amount of (IrCp*Cl2)2 and AgNTf2 in DCE and D2O, a
significant H/D scrambling was observed at the C-7 posi-
tion of indoline 1a, see Equation (5). When the reaction was
performed in the presence of a sulfonyl azide in DCE/D2O
for 1.5 min, the incorporation of deuterium was also ob-
served in unreacted 1a, which indicates that the cleavage of
the C–H bond at the C-7 position is a reversible process,
see Equation (6).
Scheme 5. Substrate scope for indolines. Reagents and conditions:
1 (0.2 mmol), 2a (0.22 mmol), (IrCp*Cl2)2 (2.5 mol-%), AgNTf2
(10 mol-%), and DCE (1 mL) at room temperature for 3 h. The
yield of the isolated product is provided.
The usefulness of this method was further demonstrated
by the development of the one-pot synthesis for 7-amino-
indoles 8a and 8b. The amidation of 1a with a sulfonyl and
acyl azide under the optimized conditions and subsequent
oxidation with MnO2 in one pot yielded 7-aminoindoles 8a
and 8b, respectively, see Equations (1) and (2). More signifi-
cantly, N-(7-indolinyl)arylamine 7c, which was accessible by
the present direct C–H amination reaction, enabled the sub-
sequent oxidative C–C coupling reaction to allow for the
preparation of pyrrolo[2,3-a]carbazole 8c, see Equation (3).
(5)
On the basis of these mechanistic studies and previous
Finally, we were pleased to find that this reaction was literature,[7] a plausible mechanistic pathway is proposed
successfully scalable, and gram amounts of substrate could (see Scheme 6). First, the treatment of a dimeric iridium
be used without a decrease to the yield. Moreover, the species with AgNTf2 affords monomeric IrCp*(NTf2)2,
amidated product was easily isolated by a simple recrystalli- which then induces the C–H cleavage of indoline 1a to pro-
zation process, see Equation (4).
duce cyclometalated IrIII complex A.[9] The azide then inter-
398
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 395–400

IrIII-Catalyzed Direct C-7 Amidation of Indolines
1
trometer. The H and 13C NMR spectroscopic data were recorded
with Bruker AM-300, Bruker AM-400, and Bruker AM-500 instru-
ments. Tetramethylsilane was used as the internal reference. The
NMR data are reported as chemical shift, multiplicity [s (singlet),
br. s (broad singlet), d (doublet), br. d (broad doublet), t (triplet),
or m (multiplet)], and coupling constant [J in Hertz (Hz)]. Silica gel
60H (200–300 mesh), manufactured by Qingdao Haiyang Chemical
Group Co. (China), was used for general chromatography. All rea-
gents were purchased from commercial sources and used without
further purification, unless otherwise indicated. [Cp*RhCl2]2,
[Cp*Rh(MeCN)3][SbF6]2, the substituted indolines, the benz-
enesulfonyl azides, the acyl azides, and the aryl azides were synthe-
sized according to published procedures.
(6)
acts with the cationic metal center of A to give B, which can
be converted into IrIII amido species C through a concerted
migratory insertion or through high valent iridium(V) ni-
trenoid species D in an oxidative manner. In each path, a
molecule of N2 is released. Finally, protonolysis of C af-
fords product 3a.
General Procedure for Direct C–H Amidation at the C-7 Position of
Indolines: (IrCp*Cl2)2 (2.5 mol-%), AgNTf2 (10 mol-%), indolines
1 (0.2 mmol), azides 2 or 4 (0.22 mmol, 1.1 equiv.), and DCE
(1 mL) were added to a test tube. The reaction mixture was stirred
at room temperature for 3 h. The resulting mixture was purified by
chromatography on a silica gel column to give product 3 or 5.
Supporting Information (see footnote on the first page of this arti-
cle): Experimental procedures, characterization of products, and
1
copies of H and 13C NMR spectra.
Acknowledgments
Support of this work by the National Natural Science Foundation
of China (NSFC) (grant number 21302200) is gratefully acknowl-
edged.
[1] a) R. J. Sundberg, Indoles, Academic Press, San Diego, 1996;
b) M. Somei, F. Yamada, Nat. Prod. Rep. 2005, 22, 73; c) T.
Kawasaki, K. Higuchi, Nat. Prod. Rep. 2005, 22, 761; d) A. J.
Kochanowska-Karamyan, M. T. Hamann, Chem. Rev. 2010,
110, 4489.
[2] a) Y. Ozawa, K. Kusano, T. Owa, A. Yokoi, M. Asada, K.
Yoshimatsu, Cancer Chemother. Pharmacol. 2012, 69, 1353; b)
T. Owa, A. Yokoi, K. Yamazaki, K. T. Yoshimatsu, T. Yamori,
T. Nagasu, J. Med. Chem. 2002, 45, 4913; c) T. Owa, H. Yosh-
ino, T. Okauchi, K. Yoshimatsu, Y. Ozawa, N. H. Sugi, T. Na-
gasu, N. Koyanagi, K. Kitoh, J. Med. Chem. 1999, 42, 3789;
d) P. Dydio, T. Zielinski, J. Jurczak, Chem. Commun. 2009,
4560; e) T. Yasuma, O. Ujikawa, M. Itoh, K. Aoki, U.S. Patent
2008/0096877 Al, 2008; f) L. C. Eli, M. G. Bell, K. Gavardinas,
D. L. Gernert, T. A. Grese, P. K. Jadhav, P. A. Lander, M. I.
Steinberg, WO 2004067529 A1, 2004.
Scheme 6. Proposed mechanism.
[3] For selected reviews on C–H activation, see: a) J. Q. Yu, Z. J.
Shi (Eds.), C–H Activation, vol. 292: Topics in Current Chemis-
try, Springer, Heidelberg, Germany, 2010; b) S. H. Cho, J. Y.
Kim, J. Kwak, S. Chang, Chem. Soc. Rev. 2011, 40, 5068; c) J.
Wencel-Delord, T. Drçge, F. Liu, F. Glorius, Chem. Soc. Rev.
2011, 40, 4740; d) L. Ackermann, Chem. Rev. 2011, 111, 1315;
e) K. M. Engle, T. S. Mei, M. Wasa, J. Q. Yu, Acc. Chem. Res.
2012, 45, 788; f) N. Kuhl, M. N. Hopkinson, J. Wencel-Delord,
F. Glorius, Angew. Chem. Int. Ed. 2012, 51, 10236; Angew.
Chem. 2012, 124, 10382; g) N. Kuhl, N. Schroder, F. Glorius,
Adv. Synth. Catal. 2014, 356, 1443.
[4] For selected reviews, see: a) I. Seregin, V. Gevorgyan, Chem.
Soc. Rev. 2007, 36, 1173; b) L. Joucla, L. Djakovitch, Adv.
Synth. Catal. 2009, 351, 673; c) G. Broggini, E. M. Beccalli, A.
Fasana, S. Gazzola, Beilstein J. Org. Chem. 2012, 8, 1730; for
selected examples, see: d) B. S. Lane, D. Sames, Org. Lett. 2004,
6, 2897; e) X. Wang, B. S. Lane, D. Sames, J. Am. Chem. Soc.
2005, 127, 4996; f) B. S. Lane, M. A. Brown, D. Sames, J. Am.
Chem. Soc. 2005, 127, 8050; g) N. R. Deprez, D. Kalyani, A.
Krause, M. S. Sanford, J. Am. Chem. Soc. 2006, 128, 4972; h)
Conclusions
In summary, we have developed a general method for the
IrIII-catalyzed C-7 selective C–H bond amidation of
indolines by using sulfonyl, acyl, and aryl azides as the
amine source. Mild and pH-neutral reaction conditions, low
catalyst loadings without external oxidants, good functional
group tolerance, and a broad substrate scope characterize
this transformation. In addition, a one-pot synthesis of 7-
aminoindoles was developed.
Experimental Section
General Methods: Mass spectrometry and high resolution mass
spectrometry were performed on a Finnigan MAT-95 mass spec-
Eur. J. Org. Chem. 2015, 395–400
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
399

W. Hou, Y. Yang, W. Ai, Y. Wu, X. Wang, B. Zhou, Y. Li
FULL PAPER
B. B. Toure, B. S. Lane, D. Sames, Org. Lett. 2006, 8, 1979; i)
D. R. Stuart, E. Villemure, K. Fagnou, J. Am. Chem. Soc. 2007,
129, 12072; j) S.-D. Yang, C.-L. Sun, Z. Fang, B.-J. Li, Y.-Z.
Li, Z.-J. Shi, Angew. Chem. Int. Ed. 2008, 47, 1473; Angew.
Chem. 2008, 120, 1495; k) L. Jiao, T. Bach, J. Am. Chem. Soc.
2011, 133, 12990; l) B. Zhou, Y. Yang, Y. Li, Chem. Commun.
2012, 48, 5163; m) S. Pan, N. Ryu, T. Shibata, J. Am. Chem.
Soc. 2012, 134, 17474; n) L. Jiao, E. Herdtweck, T. Bach, J.
Am. Chem. Soc. 2012, 134, 14563; o) B. Zhou, Y. Yang, S. Lin,
Y. Li, Adv. Synth. Catal. 2013, 355, 360; p) Z. Ding, N. Yoshi-
kai, Angew. Chem. Int. Ed. 2012, 51, 4698; Angew. Chem. 2012,
124, 4776; q) K. S. Kanyiva, Y. Nakao, T. Hiyama, Heterocy-
cles 2007, 72, 677; r) D. J. Schipper, M. Hutchinson, K. Fag-
nou, J. Am. Chem. Soc. 2010, 132, 6910; s) L. Yang, G. Zhang,
H. Huang, Adv. Synth. Catal. 2014, 356, 1509; t) B. Gong, J.
Shi, X. Wang, Y. Yan, Q. Li, Y. Meng, H. E. Xu, W. Yi, Adv.
Synth. Catal. 2014, 356, 137; u) H. Zhang, D. Liu, C. Chen,
C. Liu, A. Lei, Chem. Eur. J. 2011, 17, 9581.
Org. Biomol. Chem. 2012, 10, 8953; c) J. Ryu, K. Shin, S. H.
Park, J. Y. Kim, S. Chang, Angew. Chem. Int. Ed. 2012, 51,
9904; Angew. Chem. 2012, 124, 10042; d) D. G. Yu, M. Suri, F.
Glorius, J. Am. Chem. Soc. 2013, 135, 8802; e) B. Zhou, Y.
Yang, J. Shi, H. Feng, Y. Li, Chem. Eur. J. 2013, 19, 10511; f)
S. H. Park, J. Kwak, K. Shin, J. Ryu, Y. Park, S. Chang, J. Am.
Chem. Soc. 2014, 136, 2492; for Ru-catalyzed C–H amidations,
see: g) V. S. Thirunavukkarasu, K. Raghuvanshi, L. Acker-
mann, Org. Lett. 2013, 15, 3286; h) J. Kim, S. Chang, Chem.
Eur. J. 2013, 19, 7328; i) M. R. Yadav, R. K. Rit, A. K. Sahoo,
Org. Lett. 2013, 15, 1638; j) Q.-Z. Zheng, Y.-F. Liang, C. Qin,
N. Jiao, Chem. Commun. 2013, 49, 5654; for Ir-catalyzed amid-
ations, see: k) J. Ryu, J. Kwak, K. Shin, D. Lee, S. Chang, J.
Am. Chem. Soc. 2013, 135, 12861; l) J. Kim, S. Chang, Angew.
Chem. Int. Ed. 2014, 53, 2203. During the preparation of this
manuscript, Chang’s group reported the same transformation
by using a similar catalytic system. For details, see: K. Shin, S.
Chang, J. Org. Chem. 2014, DOI: 10.1021/jo5018475.
[5] For C–C bond formations, see: a) N. Chatani, S. Yorimitsu, T.
Asaumi, F. Kakiuchi, S. Murai, J. Org. Chem. 2002, 67, 7557;
b) Z. Shi, B. Li, X. Wan, J. Cheng, Z. Fang, B. Cao, C. Qin,
Y. Wang, Angew. Chem. Int. Ed. 2007, 46, 5554; Angew. Chem.
2007, 119, 5650; c) T. Nishikata, A. R. Abela, S. Huang, B. H.
Lipshutz, J. Am. Chem. Soc. 2010, 132, 4978; d) L. Jiao, M.
Oestreich, Chem. Eur. J. 2013, 19, 10845; e) S. R. Neufeldt,
C. K. Seigerman, M. Sanford, Org. Lett. 2013, 15, 2302; f) B.
Urones, R. G. Arrays, J. C. Carretero, Org. Lett. 2013, 15, 1120;
g) L. Jiao, M. Oestreich, Org. Lett. 2013, 15, 5374; h) Z. Song,
R. Samanta, A. P. Antonchick, Org. Lett. 2013, 15, 5662; i) S.
Pan, T. Wakaki, N. Ryu, T. Shibata, Chem. Asian J. 2014, 9,
1257; j) S. Pan, N. Ryu, T. Shibata, Adv. Synth. Catal. 2014,
356, 929.
[8]
No desired amidated product was observed by using Zhu’s con-
ditions. For details, see ref.[6]
[9] a) D. L. Davies, S. M. A. Donald, O. Al-Duaij, S. A. Mac-
gregor, M. Pölleth, J. Am. Chem. Soc. 2006, 128, 4210; b) L.
Li, W. W. Brennessel, W. D. Jones, J. Am. Chem. Soc. 2008, 130,
12414; c) L. Li, W. W. Brennessel, W. D. Jones, Organometallics
2009, 28, 3492.
[6] For a C–N bond formation, see: C. Pan, A. Abdukader, J. Han,
Y. Cheng, C. Zhu, Chem. Eur. J. 2014, 20, 3606.
[7] For Rh-catalyzed arene C–H amidations, see: a) J. Y. Kim,
S. H. Park, J. Ryu, S. H. Cho, S. H. Kim, S. Chang, J. Am.
Chem. Soc. 2012, 134, 9110; b) J. Shi, B. Zhou, Y. Yang, Y. Li,
Received: October 15, 2014
Published Online: November 27, 2014
400
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 395–400