One-pot Synthesis of a 3,4,5-triaryltriazole from the subsitituted 1,3,4-oxadiazole: Crystal structures characterization

Article abstract of DOI:10.1002/jhet.1894

Two heterocyclic compounds, 2-(p-bromophenyl)-5-(2-pyridyl)-1,3,4-oxadiazole (1) and 3-(p-bromophenyl)- 4-phenyl-5-(2-pyridyl)-1,2,4-triazole (2) were successfully synthesized and characterized by UV-vis, FTIR, ¹H NMR, ESI-MS spectra, elemental analysis, and single crystal X-ray crystallography. The structural analysis indicates that 1 is almost a planar molecule but 2 not. The crystal structure of 1 is stabilized by two kinds of intermolecular π- π interactions and two types of intermolecular C-H · N hydrogen bonds, whereas 2 by three kinds of C-H · π interactions and three types of intermolecular C-H · N hydrogen bonds. Additional, 2 can be prepared directly from 1 in an aniline solution at 190°C in a yield of 70%.

Full text of DOI:10.1002/jhet.1894

Month 2014
One-pot Synthesis of a 3,4,5-Triaryltriazole from the Subsitituted 1,3,4-
Oxadiazole: Crystal Structures Characterization
*
Jing-Jing Jiang, Guo-Ping Shen, Xin He, Xuan Shen, and Dun-Ru Zhu
College of Chemistry and Chemical Engineering, State Key Laboratory of Materials-oriented Chemical Engineering,
Nanjing University of Technology, Nanjing 210009, China
*
E-mail: zhudr@njut.edu.cn
Additional Supporting Information may be found in the online version of this article.
Received September 3, 2012
DOI 10.1002/jhet.1894
Published online 00 Month 2014 in Wiley Online Library (wileyonlinelibrary.com).
NH2
Br
N
O
N N
1
Br
N
N
N
N
2
Two heterocyclic compounds, 2-(p-bromophenyl)-5-(2-pyridyl)-1,3,4-oxadiazole (1) and 3-(p-bromophenyl)-
4-phenyl-5-(2-pyridyl)-1,2,4-triazole (2) were successfully synthesized and characterized by UV–vis, FTIR,
1H NMR, ESI-MS spectra, elemental analysis, and single crystal X-ray crystallography. The structural analysis
indicates that 1 is almost a planar molecule but 2 not. The crystal structure of 1 is stabilized by two kinds of
intermolecular p–p interactions and two types of intermolecular C–HꢀꢀꢀN hydrogen bonds, whereas 2 by three
kinds of C–Hꢀꢀꢀp interactions and three types of intermolecular C–HꢀꢀꢀN hydrogen bonds. Additional, 2 can be
prepared directly from 1 in an aniline solution at 190ꢁC in a yield of 70%.
J. Heterocyclic Chem., 00, 00 (2014).
INTRODUCTION
characterized by UV–vis, FTIR, 1H NMR, ESI-MS spectra,
elemental analysis, and single crystal X-ray crystallography.
1,3,4-Oxadiazoles and 1,2,4-triazoles, together with their
derivatives, are two kinds of important heterocyclic com-
pounds because of their diverse chemical and biological
activities including fungicide, weedicide, anti-inflammatory,
antitumor, and so on [1,2]. These compounds are also very
useful ligands in coordination chemistry because of their
rich bridging modes between transition metal ions [3,4].
Moreover, their ligand strength is in the right region to
produce iron(II) complexes with fascinating spin-crossover
properties, which can be potentially applicable to the devel-
opment of advanced devices for molecular-based electronics,
displays, and optical switches [5–13].
Recently, a series of symmetrical or asymmetrical 3,
5-disubstituted triaryltriazoles have been prepared success-
fully by our group [14–23] and others [3,10,24]. Formation
of these 3,4,5-triaryltriazoles often involves in arylphospha-
zoanilide precursors that are generally unstable and cannot
be kept for a long time. However, direct preparation of the
3,4,5-triaryltriazoles from the substituted 1,3,4-oxadiazole
is less common because the oxadiazole carbon atom need
be active with strong electron-withdrawing substituents in
order to facilitate nucleophilic attack [25–30]. In this article,
we present the direct synthesis of a 3,4,5-triaryltriazole,
3-(p-bromophenyl)-4-phenyl-5-(2-pyridyl)-1,2,4-triazole (2)
from the corresponding 1,3,4-oxadiazole, 2-(p-bromophe-
nyl)-5-(2-pyridyl)-1,3,4-oxadiazole (1) in good yield
(Scheme 1). Moreover, compounds 1 and 2 were fully
RESULTS AND DISCUSSION
In general, synthesis of 3,4,5-trisubstituted 1,2,4-triazoles
often adopts several types of intermediates including N-
acylamidrazones, dichloroaldazines, and triazolopyrazines
[26]. N-Acylamidrazones can particularly be obtained
from a large variety of precursors, such as activated amide
derivatives, amidrazones, N0-acetyl-N,N-dimethylhydrazo-
namides, oxadiazoles, N-methyl-N-nitrosoamidines, and
arylphosphazoanilides. Moreover, dichloroaldazines can be
directly derived from N-acylhydrazides and also be demon-
strated to be a simple and viable route for the synthesis of
hindered 3,4,5-trisubstituted 1,2,4-triazoles. In addition, the
use of triazolopyrazines is a practical synthetic method
leading to fused triazoles.
In our previous works [9,14–23], a large variety of
3,4,5-triaryltriazoles have been synthesized through an
intermediate arylphosphazoanilide. However, the arylpho-
sphazoanilide is unstable and its synthetic yield is not
so good. Because dichloroaldazine is a versatile and well-
known intermediate for the synthesis of hindered 3,4,
5-trisubstituted 1,2,4-triazoles, we try to use this simple
method to synthesize the target compound 2. However,
reaction of N-(p-bromophenylcarbonyl)-N0-(2-pyridylcar-
bonyl)hydrazine with thionyl chloride using our earlier
© 2014 HeteroCorporation

J. -J. Jiang, G. -P. Shen, X. He, X. Shen, and D. -R. Zhu
Vol 000
Scheme 1
Table 1
reported method [21] did not produce the corresponding
dichloroaldazine. Instead, a different intermediate 2-(p-
bromophenyl)-5-(2-pyridyl)-1,3,4-oxadiazole (1) was obtained
in a yield of 83.7%. It is well known that 1,3,4-oxadiazole
could be directly converted into corresponding 1,2,4-triazole
in the presence of an excess of amine providing the oxadiazole
carbon atoms are enough electron-deficient [31]. In order to
investigate the practicability of this reaction, we try to
reflux 1 in an aniline solution under argon atmosphere.
After 24 h, 3-(p-bromophenyl)-4-phenyl-5-(2-pyridyl)-1,2,
4-triazole (2) was obtained successfully in a yield of 70%.
Total yield of 2 is 36% based on 2-picolinic acid as a
starting material. Although p-bromophenyl and 2-pyridyl
groups are not strong electron-withdrawing substituents,
nucleophilic reaction of aniline on the oxadiazole carbon
atom can still occur [26]. However, following this
method using p-bromoaniline instead of aniline, we failed
to obtain the corresponding 3,4-bis(p-bromophenyl)-5-(2-
pyridyl)-1,2,4-trizaole, demonstrating that the reaction is
more sensitive to electron-withdrawing effect of the nucleo-
phile. This result is in agreement with those reported in the
literatures [26,32]. To our knowledge, this is the first exam-
ple that 3,4,5-triaryltriazole can be synthesized directly from
the corresponding 1,3,4-oxadiazole without any dehydrating
agents [25–30]. It is worthwhile to note that 2 has been
prepared through an intermediate N-phenylpyridine-2-
thioamide. However, total yield of 2 is only 20% based
on aniline as a starting material and its spectral data were
not provided [24].
Crystallographic data for 1 and 2.
Compounds
1
2
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C13H8BrN3O
C19H13BrN4
377.24
Triclinic
P-1
5.7792(14)
8.849(2)
15.953(4)
92.465(3)
93.527(3)
94.266(3)
811.1(3)
2
302.12
Monoclinic
P21/c
8.031(3)
13.485(5)
11.399(4)
90
99.579(4)
90
1217.3(8)
4
1.648
3.367
600
b (Å)
c (Å)
a (º)
b (ꢁ)
g (º)
V (Å3)
Z
Dc (g cmꢂ3
)
1.545
2.541
380
m (mmꢂ1
F (000)
)
Crystal size (mm)
θ Range
Reflections collected
Independent
reflections
Reflections observed
[I >2s(I)]
Data/restraints/
parameters
0.14 ꢃ 0.12 ꢃ 0.08
2.36–25.00
8418
0.16 ꢃ 0.12 ꢃ 0.10
1.3–25.00
5707
2138 (Rint = 0.026)
2817 (Rint = 0.032)
1784
2138/0/164
1.076
2310
2817/12/217
1.145
Goodness-of-fit on
F2
R/wR [I >2s(I)]
R/wR (all data)
Max., min. Δr
0.0289/0.0639
0.0374/0.0720
0.419/ꢂ0.423
0.0645/0.1799
0.0781/0.1847
0.879/ꢂ0.579
(e Åꢂ3
)
Compounds 1 and 2 were fully characterized by UV–vis,
1
FTIR, H NMR, ESI-MS spectra, and elemental analysis.
4-position. These results can be comparable with the related
compounds [14,33]. The bond lengths and bond angles in the
structures of 1 and 2 are in the usual ranges and can be
comparable with the related compounds [14,15,31,34].
Because 1 is almost a planar molecule but 2 not, their
stacking modes are quite different. There are two types
of intermolecular hydrogen bonds and two kinds of face-
to-face p–p interactions in the crystal structure of 1,
whereas there are three types of intermolecular hydrogen
bonds and three C–Hꢀꢀꢀp interactions but no p–p interaction
in the crystal structure of 2. These hydrogen bonds interac-
tions are given in Table 3. And the crystal packing diagrams
of 1 and 2 are shown in Figure 2 and Figure 3, respectively.
Besides, the face-to-face p-stacking interactions in 1 are
composed of two sections (Table 4): the first one is formed
between two parallel triazoles, and the second one between
The molecular structures of 1 and 2 were also determined
by X-ray crystallography (Table 1). The crystal structures
of 1 and 2 with atom-labeling scheme are shown in Figure 1,
and the selected bond distances and angles are summarized
in Table 2. The X-ray crystallography analysis indicates that
1 consists of two aryl rings, and one oxadiazole ring. These
rings almost share a common plane. The dihedral angles
between the pyridyl or p-bromophenyl ring and the 1,3,4-
oxadiazole are 11.0(5)ꢁ or 1.1(2)ꢁ, respectively. However,
2 consists of three aryl rings and one central 1,2,4-triazole
ring, and these rings do not share a common plane. The
pyridyl, phenyl, and p-bromophenyl rings make dihedral an-
gle of 35.3(5)ꢁ, 73.3(4)ꢁ, 25.2(4)ꢁ, respectively, with the
central 1,2,4-triazole plane. In addition, the N atom of
the pyridyl group is oriented toward the phenyl ring on
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
One-pot Synthesis of a 3,4,5-Triaryltriazole from the Subsitituted 1,3,4-Oxadiazole:
Crystal Structures Characterization
Figure 1. Views of 1 and 2 showing the atom-labeling scheme. Hydrogen atoms are omitted for clarity.
Table 2
triazole and phenyl ring. These hydrogen bonds and p–p
Selected bond lengths (Å) and angles (ꢁ) for 1 and 2.
interactions link the molecules of 1 to form an infinite chain
(Fig. 4). However, the molecules of 2 always occur in pairs with
the help of hydrogen bonds and weak C–Hꢀꢀꢀp interactions.
Furthermore, the possibility of p–p interactions disappears
because of the presence of phenyl rings on 4-position.
1
2
N1-C5
N2-N3
1.335(3)
1.402(3)
1.895(2)
1.358(3)
N1-C5
N2-N3
N4-C14
Br1-C11
C6-N2-N3
C6-C5-N1
C7-N4-C6
C10-C11-Br1
1.302(11)
1.393(9)
1.463(8)
1.891(6)
Br1-C11
O1-C6
C6-N2-N3
C6-C5-N1
C7-O1-C6
C10-C11-Br1
EXPERIMENTAL
107.7(2)
108.4(6)
116.2(2)
102.5(2)
119.1(2)
119.3(7)
104.9(5)
120.4(5)
All chemicals and solvents purchased were of analytical grade
and were used without further purification. N-(p-Bromophenylcarbonyl)-
N0-(2-pyridylcarbonyl)hydrazine was synthesized according to
Table 3
The hydrogen bonds and C–Hꢀꢀꢀp interactions in 1 and 2.
Compounds
D–HꢀꢀꢀA
d(D–H)/Å
d(HꢀꢀꢀA)/Å
d(DꢀꢀꢀA)/Å
∠D–HꢀꢀꢀA/ꢁ
1
2
C3–H3AꢀꢀꢀN3i
0.93
0.93
0.93
0.93
0.93
0.93
0.93
0.93
2.59
2.70
2.76
2.60
2.67
2.91
2.96
2.69
3.419(4)
3.405(3)
3.501(7)
3.317(9)
3.565(9)
3.702(7)
3.647(5)
3.554(1)
149
133
137
134
161
144
131
146
C4–H4AꢀꢀꢀN1ii
C4–H4AꢀꢀꢀN2iii
C18–H18AꢀꢀꢀN3iv
C19–H19AꢀꢀꢀN1v
C2-H2Aꢀꢀꢀp (C14–C19)vi
C13–H13Aꢀꢀꢀp (C14–C19)
C15–H15Aꢀꢀꢀp (C8–C13)v
Symmetry codes: (i) ꢂx, 1/2 + y, 3/2 ꢂ z; (ii) x, ꢂ1/2 ꢂ y, 1/2 + z; (iii) 2 ꢂ x, 1 ꢂ y, 1 ꢂ z; (iv) x, 1 + y, z; (v) 1 + x, y, z; (vi) 3 ꢂ x, 2 ꢂ y, 1 ꢂ z.
Figure 2. View of the crystal packing for 1 showing hydrogen bonds and pꢀꢀꢀp interactions.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

J. -J. Jiang, G. -P. Shen, X. He, X. Shen, and D. -R. Zhu
Vol 000
Figure 3. View of the crystal packing for 2 showing hydrogen bonds and C–Hꢀꢀꢀp interactions.
Table 4
spectrometer (Bruker Corporation, Billerica, Massachusetts, USA)
at ambient temperature in CDCl3. Chemical shifts are reported in
parts per million (ppm) downfield from TMS. ESI-MS was
recorded with an LCQ ADVANTAGE MAX mass spectrometer
(Thermo Fisher Scientific Inc., GmbH Bremen, Germany), with
MeOH on the mobile phase; the flow rate of the mobile phase
was 0.2 cm3 minꢂ1. The spray voltage, the capillary voltage, and
the capillary temperature were 4 kV, 40V, and 260ꢁC, respectively.
2-(p-Bromophenyl)-5-(2-pyridyl)-1,3,4-oxadiazole (1). N-
(p-Bromophenylcarbonyl)-N0-(2-pyridylcarbonyl)hydrazine (0.51 g,
1.59 mmol) was dissolved in absolute toluene (20 mL) and thionyl
chloride (0.63 mL) was added, then the reaction mixture was
refluxed at 120ꢁC for 5 h. After completion of the reaction, the
solvent and excess thionyl chloride were removed under reduced
pressure. The residue was washed with ethanol and recrystallized
from ethanol to obtain 1 as colorless crystals (0.40 g, 83.7%). mp
150–152ꢁC(uncorrected). UV–vis (MeOH, nm): 292 (1.06). FTIR
(n, cmꢂ1): 3071, 3051, 1602, 1585, 1553, 1477, 1455, 1433, 1250,
The pꢀꢀꢀp interactions in 1.
pꢀꢀꢀp
centꢀꢀꢀcent
pꢀꢀꢀp
Dihedral angle
(ꢁ)
Compound
interaction
(Å)
(Å)
3.231
—
1
p (trz)ꢀꢀꢀp
(trz)vii
3.317
3.554
0.0
p (trz)ꢀꢀꢀp
1.15
(py)viii
Symmetry codes: (vii) ꢂx, ꢂy, 1 ꢂ z; (viii) 1 ꢂ x, ꢂy, 1 ꢂ z
our earlier reported method [33]. Melting points were determined
with an X-4 digital microscope melting-point apparatus (Beijing)
and are uncorrected. Elemental analyses (C, H, N) were carried
out with a Thermo Finnigan Flash 1112A elemental analyzer
(Conquer Scientific Inc., San Diego, California, USA). UV–vis spec-
tra were recorded on a Perkin-Elmer Lambda 35 spectrophotometer
(PerkinElmer Inc., Shelton, Connecticut, USA) at room temperature
in methanol solution. FTIR spectra were recorded on a Nicolet 380
FTIR instrument (Thermo Fisher Scientific Inc., Vernon Hills,
Illinois, USA) using KBr disks in the range of 4000–400 cmꢂ1. 1H
NMR spectra were measured on a Bruker AM 300 MHz
1
1081, 1068, 1011, 833, 798, 746. H NMR (CDCl3/500 MHz), d
(ppm): 7.48–7.50 (t, 1H, PyH), 7.67–7.69 (d, 2H, ArH), 7.90–7.93
(t, 1H, PyH), 8.08–8.10 (d, 2H, ArH), 8.31–8.33 (d, 1H, PyH),
8.81–8.82 (d, 1H, PyH). ESI-MS: m/z 302.4 (M + H)+. Anal. Calcd
for C13H8BrN3O: C, 51.68; H, 2.67; N, 13.91. Found: C, 51.55; H,
2.48; N, 13.77.
Figure 4. View of a 1D infinite chain in 1 by hydrogen bonds and pꢀꢀꢀp interactions.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
One-pot Synthesis of a 3,4,5-Triaryltriazole from the Subsitituted 1,3,4-Oxadiazole:
Crystal Structures Characterization
[6] Krober, J.; Codjovi, E.; Kahn, O.; Groliere, F.; Jay, C. J Am
Chem Soc 1993, 115, 9810.
[7] van Koningsbruggen, P. J. Top Curr Chem 2004, 233, 123.
[8] Létard, J. F.; Guionneau, P.; Goux, C. L. Top Curr Chem
2004, 235, 221.
3-(p-Bromophenyl)-4-phenyl-5-(2-pyridyl)-1,2,4-triazole
(2). 1 (0.16 g, 0.53mmol) was added to aniline (7mL), then the
mixture was heated to 190ꢁC and refluxed for 24h under argon
atmosphere. After all starting material had been consumed, the
excess solvent was removed under reduced pressure. The residue
was washed with diethyl ether and recrystallized from ethanol to
obtain 2 as colorless crystals (0.14g, 70%). mp 220–221ꢁC
(uncorrected). UV–vis (MeOH, nm): 279 (0.88). FTIR (n, cmꢂ1):
[9] Zhu, D. R.; Xu, Y.; Yu, Z.; Guo, Z. J.; Sang, H.; Liu, T.; You,
X. Z. Chem Mater 2002, 14, 838.
[10] Kitchen, J. A.; Brooker, S. Coord Chem Rev 2008, 252, 2072.
[11] Murray, K. S. Eur J Inorg Chem 2008, 3101.
[12] Malcolm, A. H. Chem Soc Rev 2011, 40, 4119.
[13] Tao, J.; Wei, R. J.; Huang, R. B.; Zheng, L. S. Chem Soc Rev
2012, 41, 703.
[14] Shen, G. P.; Zhao, J.; Jiang, J. J.; Liu, Q.; Shen, X.; Xu, Y.;
Zhu, D. R.; Liu, X. Q. J Mol Struct 2011, 1002, 159.
[15] Zhu, D. R.; Song, Y.; Xu, Y.; Zhang, Y.; Fun, H. K.; You, X.
Z. Polyhedron 2000, 19, 2019.
1
3045, 2923, 1586, 1566, 1497, 1467, 1072, 1013, 823, 740. H
NMR (CDCl3/500MHz), d (ppm): 7.20–7.26 (t, 3H, PyH, ArH),
7.30–7.34 (t, 2H, ArH), 7.38–7.48 (t, 5H, ArH), 7.74–7.79 (t, 1H,
PyH), 8.12–8.15 (d, 1H, PyH), 8.32–8.33 (d, 1H, PyH). ESI-MS:
m/z 377.6 (M+ H)+. Anal. Calcd for C19H13BrN4: C, 60.49; H,
3.37; N, 14.85. Found: C, 60.59; H, 3.48; N, 14.97.
Single-crystal X-ray diffraction analysis of 1 and 2. Single
crystals of 1 and 2 suitable for X-ray crystallography were
obtained upon slow evaporation from ethanol solution at
ambient temperature. The well-shaped single crystals of 1 and
[16] Zhu, D. R.; Xu, Y.; Mei, Y. H.; Tu, C.; You, X. Z. J Mol Struct
2001, 559, 119.
[17] Zhou, J.; Yang, J.; Qi, L.; Shen, X.; Zhu, D. R.; Xu, Y.; Song,
Y. Transition Met Chem 2007, 32, 711.
[18] Chen, L.; Zhao, J.; Shen, G. P.; Shen, X.; Xu, Y.; Zhu, D. R.;
Wang, J. J Coord Chem 2011, 64, 3980.
2
were selected for lattice parameter determination and
collection of intensity data at 296 K on a Bruker SMART CCD
diffractometer with a detector distance of 5 cm and frame
exposure time of 10 s by using a graphite-monochromated Mo
Ka (l = 0.71073 Å) radiation. The structures were all solved by
direct methods and refined on F2 by full-matrix least squares
procedures using SHELXTL software (Bruker, Analytical X-ray
Systems Inc, Wisconsin USA) [35]. All non-hydrogen atoms
were anisotropically refined. All H atoms were located from a
difference map and refined isotropically. Details on crystal data
of 1 and 2 are listed in Table 1.
[19] Lu, W.; Zhu, D. R.; Xu, Y.; Cheng, H. M.; Zhao, J.; Shen, X.
Struct Chem 2010, 21, 237.
[20] Yang, J.; Bao, W. W.; Ren, X. M.; Xu, Y.; Shen, X.; Zhu, D.
R. J Coord Chem 2009, 62, 1809.
[21] Shen, G. P.; Jiang, J. J.; Sun, F.; Shen, X.; Zhu, D. R.; Liu, X.
Q. J Heterocycl Chem 2012, DOI 10.1002/jhet.1611.
[22] Zhao, J.; Cheng, H. M.; Shen, G. P.; Xu, Y.; Zhu, D. R. J
Coord Chem 2011, 64, 942.
[23] Cheng, H. M.; Zhu, D. R.; Lu, W.; Xu, R. H.; Shen, X. J
Heterocycl Chem 2010, 47, 210.
[24] Nomura, H.; Kawakami, S.; Ohsawa, N.; Seo, S. United States
Patent US 2008/0286607 Al 47.
CCDC 891976 (1) and 891977 (2) contain the supplementary
crystallographic data for this article. These data can be obtained
free of charge from the Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
[25] Yamaguchi, I.; Mitsuno, H. React Funct Polym 2011, 71, 140.
[26] Moulin, A.; Bibian, M.; Blayo, A. L.; Habnouni, S. E.;
Martinez, J.; Fehrentz, J. A. Chem Rev 2010, 110, 1809.
[27] Wang, X. Q.; Zhao, Z. G.; Liu, X. L.; Li, W. J. J Chem Res
2010, 34, 307.
[28] Aster, S. D.; Graham, D. W.; Kharbanda, D.; Patel, G.;
Ponpipom, M.; Santorelli, G. M.; Szymonifka, M. J.; Mundt, S. S.;
Shah, K.; Springer, M. S.; Thieringer, R.; Vosatka, A. H.; Wright, S.
D.; Xiao, J. Y.; Zokian, H.; Balkoveca, J. M. Bioorg Med Chem Lett
2008, 18, 2799.
Acknowledgments. This work was funded by the National Natural
Science Foundation of China (No. 20771059, 21171093) and the
State Key Laboratory of Materials-oriented Chemical Engineering
(KL11-03).
[29] Byungchan, B.; Shinya, K.; Kenji, M.; Masahiro, W. J Polym
Sci Part A: Polym Chem 2011, 49, 3863.
[30] Chiriac, C. I.; Tanasa, F.; Nechifor, M. Rev Roum Chim 2010,
55, 175.
REFERENCES AND NOTES
[31] Zhang, S. P.; Liu, Z. D.; Shao, S. C. Acta Crystallogr 2006,
E62, o1279.
[32] Reitz, D. B.; Finkes, M. J. J Heterocycl Chem 1989, 26, 225.
[33] Zhao, J.; Shen G. P.; Zhang, Y.; Shen, X.; Zhu, D. R. J Heterocycl
Chem. 2012, 49, 1114.
[1] Potts, K. T. Chem Rev 1961, 61, 87.
[2] Chang, J. J.; Wang, Y.; Zhang, H. Z.; Zhou, C. H.; Geng, R.
X.; Ji, Q. G. Chem J Chin Univ 2011, 32, 1970.
[3] Haasnoot, J. G. Coord Chem Rev 2000, 200–202, 131.
[4] Klingele, M. H.; Brooker, S. Coord Chem Rev 2003, 241,
119.
[34] Zhu, D. R.; Xu, Y.; Zhang, Y.; Wang, T. W.; You, X. Z. Acta
Crystallogr 2000, C56, 895.
[5] Kahn, O.; Martinez, C. J. Science 1998, 279, 44.
[35] Sheldrick, G. M. Acta Crystallogr 2008, A64, 112.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet