Synthesis of 1,3,4-oxadiazole-based aromatic and heterocyclic/ phenylpyrazole derivatives

Article abstract of DOI:10.1002/hc.21151

A new series of 1,3,4-oxadiazole-based aromatic and heterocyclic/ phenylpyrazole derivatives 6a-c, 7a-d, and 8 were synthesized via sequential 1,3-dipolar cyclization, hydrazidation, benzoylation, dehydrative cyclization, and the Suzuki coupling reaction.

Full text of DOI:10.1002/hc.21151

Heteroatom Chemistry
Volume 25, Number 3, 2014
Synthesis of 1,3,4-Oxadiazole-Based Aromatic
and Heterocyclic/Phenylpyrazole Derivatives
Li-Ya Wang,1,2 En-Chiuan Chang,3 Mou-Yung Yeh,3
Yu Hsuan Chung,4 Jiann-Jyh Huang,4 and Fung Fuh Wong2
1The Ph.D. Program for Cancer Biology and Drug Discovery, China Medical University, Taichung,
Taiwan 40402, Republic of China
2Graduate Institute of Pharmaceutical Chemistry, China Medical University, Taichung, Taiwan
40402, Republic of China
3Department of Chemistry, National Cheng Kung University, Tainan, Taiwan 70101, Republic of
China
4Department of Applied Chemistry, National Chiayi University, Chiayi City, Taiwan 60004,
Republic of China
Received 28 November 2013; revised 16 March 2014
INTRODUCTION
ABSTRACT: A new series of 1,3,4-oxadiazole-based
aromatic and heterocyclic/phenylpyrazole derivatives
6a–c, 7a–d, and 8 were synthesized via sequential 1,3-
dipolar cyclization, hydrazidation, benzoylation, dehy-
drative cyclization, and the Suzuki coupling reaction.
Among the derivatives, compounds 7a and 7c with
the corresponding 2-thienyl and 2-benzo[b]thienyl
(Ar) at the phenyl group located at the N-1 posi-
tion of pyrazole showed a better conjugation range.
π-Conjugated 1,3,4-oxadiazole derivatives have been
widely exploited as electron-transporting and hole-
blocking materials in electroluminescent (EL) de-
vices because of their high florescence efficiency,
thermal stability, photoluminescence (PL) quan-
tum yield, and semiconducting property [1]. There-
fore, the development of new π-conjugated 1,3,4-
oxadiazole-based heterocyclic compounds as EL
materials has attracted attention [2–4], particularly
in the blue region [1]. Representative examples
include 1,3,4-oxadiazole hybridized with pyridine
[5], pyrimidine [5], carbazole [6], 1,2,3-triazole [7],
1,2,3-triazole-pyridine [7], triazolopyridinone [8],
triazolopyridinone-carbazole [9], and spirobifluo-
rene [10].
CF3
CF3
OMe
6a. Ar =
6b. Ar =
6c. Ar =
Ph
CF3
O
N
N
S
S
S
7a. Ar =
7b. Ar =
7c. Ar =
Ar
N
N
N
O
N
S
O
Ph
7d. Ar =
8. Ar =
ꢀC
2014 Wiley Pe-
riodicals, Inc. Heteroatom Chem. 25:171–177, 2014;
View this article online at wileyonlinelibrary.com.
DOI 10.1002/hc.21151
In our previous study, we have coupled var-
ious arylpyrazoles, the electron-rich heterocycles
that have excellent thermal and morphological
stability [11]; in the conjugation, main chain of
1,3,4-oxadiazoles generates 1,3,4-oxadiazole-based
arylpyrazole derivatives with improved electron-
transporting properties [12]. To further im-
prove the conjugation range, we connected the
phenyl group in the pyrazole with an addi-
tional aryl or heteroaryl group in this study. The
aryl and heteroaryl groups included m-CF3-C6H4,
Correspondence to: Fung Fuh Wong; e-mail: wongfungfuh
@yahoo.com.tw, ffwong@mail.cmu.edu.tw.
Li-Ya Wang and En-Chiuan Chang contributed equally to this
work.
Contract grant sponsor: National Science Council of Republic
of China.
Contract grant number: NSC-102-2113-M-039-003.
Supporting Information is available in the online issue at
www.wileyonlinelibrary.com.
ꢀC
2014 Wiley Periodicals, Inc.
171

172 Wang et al.
SCHEME 1 Synthesis of 1,3,4-oxadiazole-based heterocyclic and aromatic/phenylpyrazole derivatives 6a–c, 7a–d, and 8.
2,6-di-CF3-C6H3, p-OMe-C6H4, 2-thienyl, 3-thienyl,
2-benzo[b]thienyl, dibenzo[b,d]thiophene-4-yl, and
dibenzo[b,d]furane-4-yl that have important prop-
erties to form conducting polymers [13–18]. These
new 1,3,4-oxadiazole-based aromatic and hetero-
cyclic/phenylpyrazole derivatives 6a–6c, 7a–7d, and
8 were obtained by the use of sequential 1,3-dipolar
cycloaddition, substitution, benzoylation, dehydra-
tive cyclization, and the Suzuki coupling reaction.
sponding dimethyl 1-(p-bromophenyl)-1H-pyrazole-
3,4-dicarboxylate (2) in 92% of the yield [20]. This ef-
ficient 1,3-dipolar cycloaddition be able to apply for
scale-up manufacture of pyrazole derivatives from
sydnones [21, 22]. A treatment of compound 2 with
hydrazine hydrate afforded the corresponding dihy-
drazide 3 in 94% yield [23]. Dihydrazide 3 was then
reacted with benzoyl chloride in pyridine to give the
corresponding dibenzoyl dihydrazide 4 in 85% yield.
A reaction of compound 4 with POCl3 formed the
pyrazole–1,3,4-oxadiazole 5 in 81% yield [24].
Compound 5 was then cross-coupled with vari-
ous arene- and heteroarene-boronic acids, includi-
ng m-CF3–C6H4–, 2,6-di-CF3–C6H3–, p-OMe-C6H4-,
2-thienyl-, 3-thienyl-, 2-benzo[b]thienyl, dibenzo
[b,d]thiophene-4-yl-, and dibenzo[b,d]furane-4-yl-
boronic acids (see Scheme 1) [25] using the Suzuki
coupling reaction [26]. The reaction provided the
corresponding 1,3,4-oxadiazole-based aromatic and
heterocyclic/phenylpyrazole derivatives 6a–c, 7a–
d, and 8 in 72–87% yields (see Scheme 1 and
Table 1).
RESULTS AND DISCUSSION
Synthesis of 1,3,4-Oxadiazole-Based
Heterocyclic and Aromatic/Phenylpyrazole
Derivatives 6a–c, 7a–d, and 8
Scheme 1 shows the synthetic route for 1,3,4-
oxadiazole-based aromatic and heterocyclic/phen
ylpyrazole derivatives 6a–c, 7a–d, and 8. N1-p-
Bromophenylsydnone 1, prepared according to the
literature procedure [19], was reacted with dimethyl
acetylenedicaboxylate (DMAD) to give the corre-
Heteroatom Chemistry DOI 10.1002/hc

Synthesis of 1,3,4-Oxadiazole-Based Aromatic and Heterocyclic/Phenylpyrazole Derivatives 173
TABLE 1 Synthesis of 1,3,4-Oxadiazole-Based Aromatic
and Heterocyclic/Phenylpyrazole Derivatives 6a–c, 7a–d,
and 8 from 5 with Various Boronic Acids
Entry
ArB(OH)2 Ar =
m-CF3–C6H4-
2,6-Di-CF3-C6H3-
p-OMe-C6H4-
2-Thienyl-
3-Thienyl-
2-Benzo[b]thienyl-
Dibenzo[b,d]thiophene-4-yl-
Dibenzo[b,d]furane-4-yl-
Compound Yield (%)
1
2
3
4
5
6
7
8
6a
6b
6c
7a
7b
7c
7d
8
82
72
86
81
87
74
83
85
TABLE 2 Spectroscopic Data of 5 and the New 1,3,4-
Oxadiazole-Based Aromatic and Heterocyclic/Phe
nylpyrazole Derivatives 6a–c, 7a–d, and 8 in CH2Cl2
FIGURE 1 The UV–vis and PL spectra of 6a–c in CH2Cl2
solution.
Absorbance
λmax
(UV–vis,
nm)
Emission
λmax (PL,
nm)
Entry
Compound
ꢀfa
1
2
3
4
5
6
7
8
9
5
279
299
303
307
315
304
326
269
290
361
384
369
413
399
398
399
383
387
-
6a
6b
6c
7a
7b
7c
7d
8
0.68
0.67
0.67
0.71
0.73
0.70
0.76
0.74
aFluorescence quantum efficiency, relative to 2-phenyl-5-(4-
biphenyl)-1,3,4-oxadiazole in benzene (ꢀf = 0.8).
FIGURE 2 The UV–vis and PL spectra of 7a–c in CH2Cl2
solution.
Optical Properties
1,3,4-Oxadiazole-based aromatic and hetero-
cyclic/phenylpyrazole derivatives 6a–c, 7a–d, and
8 showed similar λmax (at 299–307, 269–326, and
290 nm, respectively) in the UV–vis spectra mea-
sured in CH2Cl2 (Table 2). For the UV–vis spectra of
6a–c and 7a–c as shown in Figs. 1 and 2, the main ab-
sorption bands at ꢀ290 nm were contributed by the
conjugation of phenyl and pyrazole moieties as indi-
cated in our previously published results [12]. Com-
pounds 6a–c have a slightly redshift (299–307 nm)
in comparison with 5, possibly due to the con-
jugation resulting from the additional aryl group
connected to the N1-phenyl group in the pyrazolic
ring. Compounds 7a–c with 2-thienyl, 3-thienyl,
and 2-benzo[b]thienyl groups at the paraposition
of the N1-phenylpyrazole also showed a slightly
redshift with λmax values of 304–326 nm. For
compounds 7d and 8, they showed very similar
absorption peaks (at 269 and 290 nm, respectively)
to that of the starting material 5 in the visible
region (see Fig. 3). We thought that the steric repul-
sion between bulky dibenzo[b,d]thiophene-4-yl or
dibenzo[b,d]furane-4-yl substituents with an 1,3,4-
oxadiazole-based phenylpyrazole core structure
may exist. As a result, dibenzo[b,d]thiophene-4-yl
and dibenzo[b,d]furane-4-yl groups may not favor
conjugation with phenylpyrazole.
Table 2 also shows the emission λmax of com-
pounds 5, 6a–c, 7a–d, and 8 in their PL spec-
tra measured in CH2Cl2. Except for compound
6b, these compounds showed a redshift in λmax
by ࣙ15 nm in comparison with 5 (λmax for
5: 361 nm). For 6a–c bearing the substituted
phenyl group at the phenylpyrazole moiety, the
emission λmax was observed at 369–413 nm (see
Fig. 1). Compound 6c bearing two strong electron-
withdrawing CF3 groups showed the strongest red-
shift in the PL emission spectrum (at ꢀ413 nm;
see Fig. 1). For compounds 7a–d and 8 con-
taining the corresponding 2-thienyl, 3-thienyl,
2-benzo[b]thiophenyl, dibenzofuranyl, and diben-
zothiophenyl groups, their PL showed a slightly
Heteroatom Chemistry DOI 10.1002/hc

174 Wang et al.
matography was carried out on silica gel (230–
400 mesh). Tetrakis(triphenylphosphine)palladium,
toluene, silica gel and p-xylene were purchased
from Merck Chemical Co. Dichloromethane, chlo-
roform, ethanol, hydrazine hydrate, methanol,
and tetrahydrofuran were purchased from Fluka
&
Aldrich. Benzoyl chloride, benzo[b]thien-2-
ylboronic acid, 4-dibenzothienylboronic acid, 4-
(dibenzofuranyl)boronic acid, dimethyl acetylened-
icaboxylate, diphenylacetylene, phenylacetylene,
potassium carbonate, pyridine, phosphorus oxychlo-
ride, 2-thienylboronic acid, and 3-thienylboronic
acid were purchased from Acros Chemical Co. Potas-
sium carbonate was purchased from TCI Chemical
Co.
Infrared (IR) spectra were measured on a
Bomem Michelson Series FT-IR spectrometer. The
wave numbers reported are referenced to the
polystyrene 1601 cm−1 absorption. Absorption in-
tensities are recorded by the following abbrevia-
tions: s, strong; m, medium; w, weak. UV–visible
spectra were measured with a HP 8452A diode-
array spectrophotometer. PL spectra were obtained
on a PerkinElemer fluorescence spectrophotometer
(LS 55). Proton NMR spectra were obtained on a
Bruker AC-300 (300 MHz) spectrometer by the use
of DMSO-d6 as the solvent. Carbon-13 NMR spectra
were obtained on a Bruker AC-300 (75 MHz) spec-
trometer by using of DMSO-d6 as a solvent. Carbon-
13 chemical shifts are referenced to the center of
the DMSO-d6 sextet (δ 39.6 ppm). Multiplicities are
recorded by the following abbreviations: s, singlet;
d, doublet; t, triplet; q, quartet; m, multiplet; J, cou-
pling constant (hertz).
FIGURE 3 The UV–vis and PL spectra of 7d and 8 in CH2Cl2
solution.
redshift with λmax at 383–399 nm. Following the
results from UV–vis and PL, we assumed that
the different substituents at the paraposition of the
phenyl ring located at the phenylpyrazole group, in-
cluding aryl, 4-dibenzofuranyl, 2- or 3-thiophenyl,
2-benzo[b]thiophenyl, 4-dibenzofuranyl, and 4-
dibenzothiophenyl groups, seemed to conjugate
with a 1,3,4-oxadiazole-based phenylpyrazole core
backbone, especially for 2-thiophenyl and 2-
benzo[b]thiophenyl groups. On the other hand, the
solution fluorescence quantum yields (ꢀf) of 5, 6a–c,
7a–d, and 8, all of which fall in the range of 0.67–
0.76, were determined relative to that of 2-phenyl-5-
(4-biphenyl)-1,3,4-oxzdiazole in benzene (ꢀf = 0.80;
see Table 2).
In conclusion, a series of 1,3,4-oxadiazole-based
aromatic and heterocyclic/phenylpyrazole deriva-
tives were successfully synthesized by sequential
1,3-dipolar cycloaddition, hydrazidation, benzoyla-
tion, dehydrative cyclization, and the Suzuki cou-
pling reaction. Aryl, dibenzofuranyl, 2-thiophenyl,
3-thiophenyl, 2-benzo[b]thiophenyl, and dibenzoth-
iophenyl were introduced to the 1,3,4-oxadiazole-
phenylpyrazole main structure to promote the
conjugation range. Based on spectroscopic stud-
ies including UV–vis and PL, compounds 7c
and 7d with the respective 2-thiophenyl and 2-
benzo[b]thiophenyl groups possessed the more con-
jugation efficiency.
The UV–vis spectra of the samples were mea-
sured in NMP by a Shimadzu model UV-160
spectrophotometer. The fluorescence spectra were
recorded by a Hitachi F-4500 fluorescence spectrom-
eter. Elemental analyses were carried out on a Her-
aeus CHN–O RAPID element analyzer.
Synthesis of Dimethyl 1-(4-Bromophenyl)-1H-
pyrazole-3,4-dicarboxylate (2)
A solution of sydnone 1 (0.20 g, 1.0 equiv) in 4.0 mL
p-xylene was added DMAD (1.05 equiv). The reac-
tion mixture was heated at reflux for 6.0 h. After the
reaction was completed, the solution was concen-
trated under reduced pressure to remove p-xylene.
The residue was purified by column chromatogra-
phy on silica gel to give 2 in 92% yield [20]: 1H NMR
(DMSO-d6, 300 MHz) δ 3.76 (s, 3H, OCH3), 3.84 (s,
3H, OCH3), 7.66 (d, J = 7.8 Hz, 2H, ArH), 7.83 (d,
J = 7.8 Hz, 2H, ArH), 9.08 (s, 1H, ArH); 13C NMR
(75 MHz, DMSO-d6) δ 52.1, 52.7, 115.6, 120.9, 121.6,
EXPERIMENTAL
General
All chemicals were reagent grade and used as
purchased. All reactions were carried out un-
der nitrogenous atmosphere and monitored by
thin-layer chromatography. Flash column chro-
Heteroatom Chemistry DOI 10.1002/hc

Synthesis of 1,3,4-Oxadiazole-Based Aromatic and Heterocyclic/Phenylpyrazole Derivatives 175
132.7, 132.9, 137.7, 144.7, 161.6, 162.2; Anal. calcd
for C13H11BrN2O4: C 46.04; H 3.27; N 8.26; found: C
46.10; H 3.24; N 8.21.
washed with cold water (5.0 mL). The solids were re-
crystallized from EtOH to give the desired 5 in 81%
yield [25]: 1H NMR (DMSO-d6, 300 MHz) δ 7.60–7.83
(m, 10H, ArH), 7.86 (d, J = 7.5 Hz, 2H, ArH), 8.07 (d,
J = 7.5 Hz, 2H, ArH), 9.69 (s, 1H, ArH); 13C NMR (75
MHz, DMSO-d6) δ 109.1, 122.1, 123.5, 123.6, 127.0,
127.4, 129.1, 129.6, 130.0, 131.8, 132.0, 132.1, 135.0,
136.2, 137.0, 158.1, 158.3, 165.0, 166.2; Anal. calcd
for C25H15BrN6O2: C 58.72; H 2.96; N 16.44; found:
C 58.67; H 2.92; N 16.50.
Synthesis of 1-(p-Bromophenyl)-1H-pyrazole-
3,4-dicarbohydrazide (3)
A solution of 2 (0.51 g, 1.5 mmol, 1.0 equiv) and hy-
drazine monohydrate (0.76 g, 6.0 mmol, 4.0 equiv)
in EtOH was heated at reflux for 12 h. After the reac-
tion was completed, the solution was concentrated
under reduced pressure and precipitated by EtOAc
(15 mL). The resulting solution was kept at –5°C for 4
h. The precipitate was filtered and washed with cold
EtOH (10 mL). The solids were dried in a vacuum
oven for 12 h to give the desired 3 in 94% yield [23]:
1H NMR (DMSO-d6, 300 MHz) δ 4.68 (br, 4H, NH2),
7.61 (d, J = 8.9 Hz, 2H, ArH), 8.06 (d, J = 8.9 Hz, 2H,
ArH), 9.09 (s, 1H, ArH), 10.36 (br, 2H, NH), 11.19
(s, 1H, NH); 13C NMR (75 MHz, DMSO-d6) δ 119.3,
120.6, 121.4, 132.6, 132.2, 138.0, 141.9, 160.1, 161.1;
Anal. calcd for C11H11BrN6O2: C 38.96; H 3.27; N
24.78; found: C 38.89; H 3.22; N 24.85.
Standard Procedure for the Synthesis of 1,3,4-
Oxadiazole-Based Aromatic and Heterocyclic/
Phenylpyrazole Derivatives 6a–c, 7a–d, and 8
Compound
or heteroaryl-boronic acid (ꢀ10 mmol, 2.0
equiv), tetrakis(triphenylphosphine)palladium
5
(ꢀ5.0 mmol, 1.0 equiv), aryl-
(ꢀ0.20 mmol, 0.04 equiv), and potassium car-
bonate (2.0 M in H2O, ꢀ15 mmol, 3.0 equiv) in
p-xylene/EtOH (40/20 mL) were heated at reflux
for 24 h under N2. The solution was concentrated,
added with water (10 mL), and extracted with
dichloromethane (3 × 50 mL). The combined
organic layer was washed with a saturated aqueous
NaHCO3 (20 mL) and brine (20 mL). The solution
was dried over MgSO4(s) and concentrated under
reduced pressure. The residue was purified by
column chromatography on silica gel using hex-
anes as an eluent. The collected compounds were
recrystallized from a mixture of EtOAc and EtOH
to afford the corresponding 6a–c, 7a–d, and 8 [25].
Synthesis of Dibenzoyl-1-(4-bromophenyl)-1H-
pyrazole-3,4-dicarbohydrazide (4)
To a solution of 3 (2.0 g, 5.9 mmol, 1.0 equiv) in
pyridine (20 mL) in an ice bath, benzoyl chloride
(2.7 g, 23.7 mmol, 4.0 equiv) was added. The reac-
tion mixture was stirred at 80°C for 5 h. After the
reaction was completed, the reaction mixture was
concentrated under reduced pressure. The residue
was recrystallized from EtOH to give the desired 4
in 85% yield: 1H NMR (DMSO-d6, 300 MHz) δ 7.48–
7.56 (m, 6H, ArH), 7.80–7.96 (m, 4H, ArH), 8.05 (d,
J = 8.4 Hz, 2H, ArH), 8.18 (d, J = 8.7 Hz, 2H, ArH),
9.33 (s, 1H, ArH), 10.73 (s, 1H, NH), 10.76 (s, 1H,
NH), 11.20 (s, 1H, NH), 11.90 (s, 1H, NH); 13C NMR
(75 MHz, DMSO-d6) δ 117.0, 119.2, 121.7, 127.7,
128.7, 128.8, 132.1, 132.7, 132.4, 134.3, 134.7, 137.7,
137.8, 141.0, 141.3, 159.7, 162.1, 165.9, 167.0; Anal.
calcd for C25H19BrN6O4: C 54.86; H 3.50; N 15.35;
found: C 54.81; H 3.51; N 15.38.
5,5ꢁ-(1-(3ꢁ-(Trifluoromethyl)-[1,1ꢁ-biphenyl]-4-
yl)-1H-pyrazole-3,4-diyl)bis(2-phenyl-1,3,4-
oxadiazole) (6a). 1H NMR (CDCl3, 300 MHz)
δ 7.44–7.57 (m, 6H, ArH), 7.62–7.67 (m, 2H, ArH),
7.76–7.82 (m, 3H, ArH), 7.86 (s, 1H, ArH), 7.98 (d,
J = 8.4 Hz, 2H, ArH), 8.11 (d, J = 7.2 Hz, 2H, ArH),
8.18 (d, J = 7.2 Hz, 2H, ArH), 8.78 (s, 1H, ArH); 13C
NMR (75 MHz, CDCl3) δ 108.9, 120.3, 123.4, 123.5,
123.7, 123.8, 124.6, 127.0, 127.3, 128.5, 129.1, 129.5,
130.0, 130.3, 131.2, 131.6, 131.9, 132.1, 136.3, 138.2,
140.0, 140.2, 158.1, 158.5, 165.0, 165.3; Anal. calcd
for C32H19F3N6O2: C 66.67; H 3.32; N 14.58; found:
C 66.71; H 3.22; N 14.65.
Synthesis of 5,5ꢁ-(1-(4-Bromophenyl)-1H-
pyrazole-3,4-diyl)bis(2-phenyl-1,3,4-oxadiazole)
(5)
5,5ꢁ-(1-(3ꢁ,5ꢁ-Bis(trifluoromethyl)-[1,1ꢁ-biphenyl]-
4-yl)-1H-pyrazole-3,4-diyl)bis(2-phenyl-1,3,4-
Compound 4 (2.3 g, 4.2 mmol, 1.0 equiv) was dis-
solved in POCl3 (10 mL), and the resultant solu-
tion was heated at 90°C for 12 h. After the reaction
was completed, the reaction mixture was added with
cold water (10 mL) and neutralized with aqueous
NaHCO3 (10 mL). The precipitate was filtrated and
oxadiazole) (6b). 1H NMR (CDCl3, 300 MHz)
δ 7.45–7.60 (m, 6H, ArH), 7.82 (d, J = 8.4 Hz, 2H,
ArH), 7.92 (s, 1H, ArH), 8.04–8.06 (m, 4H, ArH),
8.12 (d, J = 7.2 Hz, 2H, ArH), 8.19 (d, J = 7.2 Hz,
2H, ArH), 8.90 (s, 1H, ArH); 13C NMR (75 MHz,
CDCl3) δ 109.1, 120.5, 121.6, 123.4, 123.5, 125.0,
Heteroatom Chemistry DOI 10.1002/hc

176 Wang et al.
127.1, 127.3, 128.7, 129.1, 130.1, 131.9, 132.1, 132.7,
136.5, 138.4, 138.9, 141.6, 153.1, 154.1, 158.1, 158.4,
165.1, 165.3; Anal. calcd for C33H18F6N6O2: C 61.50;
H 2.81; N 13.04; found: C 61.59; H 2.85; N 13.01.
70.20; H 3.57; N 14.88; found: C 70.11; H 3.48; N
14.96.
5,5ꢁ-(1-(4-(Dibenzothiophen-4-yl)phenyl)-1H-
pyrazole-3,4-diyl)bis(2-phenyl-1,3,4-oxadiazole) (7d).
1H NMR (CDCl3, 300 MHz) δ 7.44–7.61 (m, 10H,
ArH), 7.86–7.89 (m, 1H, ArH), 7.96 (d, J = 8.7 Hz,
2H, ArH), 8.05 (d, J = 8.4 Hz, 2H, ArH), 8.15 (d, J =
7.2 Hz, 2H, ArH), 8.22 (d, J = 8.1 Hz, 4H, ArH), 8.90
(s, 1H, ArH); 13C NMR (75 MHz, CDCl3) δ 108.5,
120.3, 121.1, 121.8, 122.7, 123.5, 123.6, 124.6, 125.3,
126.9, 127.0, 127.1, 127.3, 129.1, 129.8, 130.2, 131.9,
132.1, 132.3, 135.3, 135.6, 136.5, 138.1, 138.4, 139.3,
141.1, 158.1, 158.5, 164.8, 165.0; Anal. calcd for
C37H22N6O2S: C 72.30; H 3.61; N 13.67; found: C
72.26; H 3.67; N 13.74.
5,5ꢁ-(1-(4ꢁ-Methoxy-[1,1ꢁ-biphenyl]-4-yl)-1H-
pyrazole-3,4-diyl)bis(2-phenyl-1,3,4-oxadiazole) (6c).
1H NMR (CDCl3, 300 MHz) δ 3.87 (s, 3H, OCH3),
7.01 (d, J = 8.4 Hz, 2H, ArH), 7.48–7.60 (m, 8H,
ArH), 7.73 (d, J = 8.1 Hz, 2H, ArH), 7.92 (d, J = 8.1
Hz, 2H, ArH), 8.13 (d, J = 7.2 Hz, 2H, ArH), 8.20 (d,
J = 7.2 Hz, 2H, ArH), 8.83 (s, 1H, ArH); 13C NMR
(75 MHz, CDCl3) δ 55.0, 108.2, 114.0, 119.8, 123.0,
123.1, 125.8, 126.7, 126.9, 127.4, 127.7, 128.7, 129.6,
131.4, 131.5, 131.6, 135.7, 136.7, 140.9, 148.9, 158.1,
159.3, 164.5, 164.8; Anal. calcd for C32H22N6O3: C
71.37; H 4.12; N 15.60; found: C 71.29; H 4.16; N
15.51.
5,5ꢁ-(1-(4-(Dibenzofuran-4-yl)phenyl)-1H-
pyrazole-3,4-diyl)bis(2-phenyl-1,3,4-oxadiazole)
(8). 1H NMR (CDCl3, 300 MHz) δ 7.38–7.44 (m,
2H, ArH), 7.49–7.55 (m, 5H, ArH), 7.62–7.67 (m,
3H, ArH), 7.97–8.05 (m, 5H, ArH), 8.11–8.15 (m,
4H, ArH), 8.21 (d, J = 6.9 Hz, 2H, ArH), 8.88 (s,
1H, ArH); 13C NMR (75 MHz, CDCl3) δ 108.4,
111.4, 119.6, 120.0, 120.3, 122.6, 122.9, 123.5, 123.7,
124.7, 126.1, 126.7, 126.9, 127.0, 128.2, 128.7, 129.7,
131.4, 131.5, 131.6, 131.7, 136.5, 137.4, 152.8, 153.7,
155.7, 157.8, 158.1, 164.6, 164.8; Anal. calcd for
C37H22N6O3: C 74.24; H 3.70; N 14.04; found: C
74.28; H 3.65; N 14.10.
5,5ꢁ-(1-(4-(Thiophen-2-yl)phenyl)-1H-pyrazole-
3,4-diyl)bis(2-phenyl-1,3,4-oxadiazole)
(7a). 1H
NMR (CDCl3, 300 MHz) δ 7.10–7.13 (m, 1H, ArH),
7.34–7.39 (m, 2H, ArH), 7.47–7.57 (m, 6H, ArH),
7.77 (d, J = 7.2 Hz, 2H, ArH), 7.89 (d, J = 7.5 Hz,
2H, ArH), 8.12 (d, J = 6.6 Hz, 2H, ArH), 8.19 (d,
J = 7.2 Hz, 2H, ArH), 8.83 (s, 1H, ArH); 13C NMR
(75 MHz, CDCl3) δ 108.7, 120.3, 123.4, 123.5, 124.0,
125.8, 127.0, 127.1, 127.3, 128.3, 128.6, 129.1, 130.0,
131.9, 132.1, 134.8, 136.1, 137.4, 142.5, 158.2, 158.5,
164.9, 165.2; Anal. calcd for C29H18N6O2S: C 67.69;
H 3.53; N 16.33; found: C 67.62; H 3.47; N 16.41.
5,5ꢁ-(1-(4-(Thiophen-3-yl)phenyl)-1H-pyrazole-
3,4-diyl)bis(2-phenyl-1,3,4-oxadiazole)
REFERENCES
(7b). 1H
NMR (CDCl3, 300 MHz) δ 7.44–7.59 (m, 9H, ArH),
7.78 (d, J = 8.4 Hz, 2H, ArH), 7.90 (d, J = 8.4 Hz,
2H, ArH), 8.13 (d, J = 7.2 Hz, 2H, ArH), 8.20 (d,
J = 7.2 Hz, 2H, ArH), 8.83 (s, 1H, ArH); 13C NMR
(75 MHz, CDCl3) δ 108.6, 120.4, 120.6, 123.8, 123.8,
126.8, 127.0, 127.5, 127.7, 128.1, 128.3, 128.7, 130.1,
131.4, 133.6, 134.7, 136.6, 136.9, 140.6, 158.2, 158.9,
165.2, 165.5; Anal. calcd for C29H18N6O2S: C 67.69;
H 3.53; N 16.33; found: C 67.60; H 3.58; N 16.25.
[1] Tang, C. W.; van Slyke, S. A. Appl Phys Lett 1987, 51,
913–915.
[2] (a) Brunner, K.; van Dijken, A.; Bo¨rner, H.; Basti-
aansen, J. J. A. M.; Kiggen, N. M. M.; Langeveld, B.
M. W. J Am Chem Soc 2004, 126, 6035–6042; (b)
Kim, Y. H.; Lee, S. J.; Byeon, K. N.; Kim, J. S.; Shin,
S. C.; Kwon, S. K. Bull Korean Chem Soc 2007, 28,
443–444.
[3] (a) Wong, K.-T.; Chien, Y.-Y.; Chen, R.-T.; Wang, C.-
F.; Lin, Y.-T.; Chiang, H.-H.; Hsieh, P.-Y.; Wu, C.-C.;
Chou, C. H.; Su, Y. O.; Lee, G. H.; Peng, S.-M. J Am
Chem Soc 2002, 124, 11576–11577; (b) Jia, W.-L.;
McCormick, T.; Liu, Q.-D.; Fukutani, H.; Motala, M.;
Wang, R.-Y.; Tao, Y.; Wang, S. J Mater Chem 2004,
14, 3344–3350.
[4] (a) Wu, C.-H.; Chien, C.-H.; Hsu, F.-M.; Shih, P.-
I.; Shu, C.-F. J Mater Chem 2009, 19, 1464–1470;
(b) Kim, Y.-H.; Jeong, H.-C.; Kim, S.-H.; Yang, K.;
Kwon, S.-K. Adv Funct Mater 2005, 15, 1799–1805;
(c) Hughes, G.; Bryce, M. R. J Mater Chem 2005, 15,
94–107; (d) Adachi, C.; Tsutsui, T.; Saito, S.; Appl
Phys Lett 1990, 56, 799–801.
5,5ꢁ-(1-(4-(Benzo[b]thiophen-2-yl)phenyl)-1H-
pyrazole-3,4-diyl)bis(2-phenyl-1,3,4-oxadiazole) (7c).
1H NMR (CDCl3, 300 MHz) δ 7.26–7.60 (m, 8H,
ArH), 7.64 (s, 1H, ArH), 7.80–8.01 (m, 6H, ArH),
8.13 (d, J = 7.2 Hz, 2H, ArH), 8.20 (d, J = 7.2 Hz, 2H,
ArH), 8.84 (s, 1H, ArH); 13C NMR (75 MHz, CDCl3) δ
108.7, 119.3, 120.9, 122.4, 123.7, 123.8, 124.0, 124.2,
125.0, 127.5, 127.7, 127.9, 128.8, 130.2, 132.1, 132.5,
132.6, 133.2, 138.2, 139.1, 140.3, 141.4, 143.2 158.3,
158.7, 164.4, 164.7; Anal. calcd for C33H20N6O2S: C
[5] Wang, C.; Jung, G.-Y.; Batsanov, A. S.; Bryce, M. R.;
Petty, M. C. J Mater Chem 2002, 12, 173–180.
Heteroatom Chemistry DOI 10.1002/hc

Synthesis of 1,3,4-Oxadiazole-Based Aromatic and Heterocyclic/Phenylpyrazole Derivatives 177
[6] (a) Guan, M.; Bian, Z. Q.; Zhou, F. Y.; Li, Z. J.; Haung,
[17] Aaron, J. J.; Fall, M. Spectrochim Acta, Part A 2000,
56, 1391–1397.
[18] Fall, M.; Aaron, J. J.; Gningue-Sall, D. J. Fluorescence
2000, 10, 107–112.
C. H. Chem Commun 2003, 9, 2708–2709; (b) Zhang,
Q.; Chen, J.; Cheng, Y.; Wang, L.; Ma, D.; Jing, X.;
Wang, F. J Mater Chem 2004, 14, 895–900.
[7] Zhou, J.-X.; Wong, F. F.; Chen, C.-Y.; Yeh, M.-Y. Het-
eroatom Chem 2006, 17, 322–328.
[8] (a) Shin, M.-H.; Wong, F. F.; Lin, C.-M.; Chen, W.-Y.;
Yeh, M.-Y. Heteroatom Chem 2007, 18, 212–219; (b)
Chiang, K.-C.; Wong, F. F.; Chang, C.-S.; Hour, M.-
J.; Wang, Y.-L.; Wen, S.-B.; Yeh, M.-Y. J Heterocycl
Chem 2007, 44, 591–596.
[9] (a) Shin, M.-H.; Wong, F. F.; Lin, C.-M.; Chen, W.-Y.;
Yeh, M.-Y. Heteroatom Chem 2006, 17, 160–165; (b)
Chang, H.-T.; Chiang, K.-C.; Wong, F. F.; Yeh, M.-Y.
Heterocyles 2006, 68, 1585–1594.
[10] Chien, Y.; Wong, K.; Chou, P.; Cheng, Y. Chem Com-
mun 2002, 2874–2875.
[19] (a) Yeh, M.-Y.; Tien, H.-J.; Huang, L.-Y.; Chen, M.-H.
J Chin Chem Soc 1983, 30, 29–37; (b) Chang, E.-M.;
Chen, T.-H.; Wong, F. F.; Chiang, K.-C.; Yeh, M.-Y.
Heterocyles 2006, 68, 1007–1015; (c) Chang, E.-M.;
Chen, T.-H.; Wong, F. F.; Chang, E.-C.; Yeh, M.-Y.
Synlett 2006, 6, 901–904.
[20] Dumitrascu, F.; Mitan, C. I.; Dumitrescu, D.;
Dra˜ghici, C.; Ca˜proiu, M. T. Arkivoc 2002, 80–86.
[21] Chang, E.-M.; Lee, C.-T.; Chen, C.-Y.; Wong, F. F.;
Yeh, M.-Y. Aust J Chem 2008, 61, 342–349.
[22] Chang, E.-M.; Huang, S.-L.; Lee, C.-T.; Lin, H. C.;
Chen, C.-Y.; Huang, Y.-Y.; Wong, F. F. Aust J Chem
2009, 62, 1355–1362.
[11] Tao, Y. T.; Chuen, C. H.; Ko, C. W.; Peng, J. W. Chem
Mater 2002, 14, 4256–4261.
[12] Chang, E.-M.; Lin, C.-J.; Wong, F. F.; Yeh, M.-Y. Het-
erocyles 2006, 68, 733–748.
[23] (a) Mayer, H.; Staffen, F. Monatsh Chem 1913, 34,
525–18; (b) Shinohara, H.; Ichimiya, Y.; Yoshimura,
T.; Okawara, M. Kobunshi Kagaku 1958, 15, 839;
Chem Abstr 1960, 54, 22636i.
[13] Ng, C.; Xu, S. J. M.; Chan, H. S. O. Synth Met 1998,
92, 33–37.
[14] Ng, S. C.; Xu, L. G.; Chan, S. O. Synth Met 1998, 94,
185–191.
[15] Sato, T.; Fujitsuka, M.; Segawa, H.; Shimidzu, T.;
Tanaka, K. Synth Met 1998, 95, 107–112.
[16] Fall, M.; Aaron, J. J.; Dieng, M. M.; Parkanyi, C. Poly-
mer 2000, 41, 4047–4055.
[24] Wang, C.; Jung, G.-Y.; Hua, Y.; Pearson, C.; Bryce, M.
R.; Petty, M. C. A.; Batsanov, S.; Goeta, A. R.; Howard,
J. A. Chem Mater 2001, 13, 1167–1173.
[25] Qian, Y.; Marugan, J. J.; Fossum, R. D.; Vogt, A.;
Sebti, S. M.; Hamilton, A. D. Bioorg Med Chem 1999,
7, 3011–3024.
[26] Miyaura, N.; Suzuki, A. Chem Rev 1995, 95, 2457–
2483.
Heteroatom Chemistry DOI 10.1002/hc