Cu1.5PMo12O40-catalyzed condensation cyclization for the synthesis of substituted pyrazoles

Article abstract of DOI:10.1002/aoc.4532

A convenient and direct approach has been developed for the preparation of pyrazole derivatives by the condensation cyclization of hydrazines/hydrazide and 1,3-diketones in the presence of Cu_1.5PMo₁₂O₄₀ (0.33?mol%) under mild conditions (r.t.-60?°C, 10–30?min). Notably, the reaction was found to be scalable as 99% yield was obtained when the reaction was performed at a 5-mmol scale. This solvent-free and halogen-free catalytic system represents an effective economic and environmentally friendly method for the construction of pyrazoles.

Full text of DOI:10.1002/aoc.4532

Received: 18 May 2018
DOI: 10.1002/aoc.4532
Revised: 5 July 2018
Accepted: 9 July 2018
F U L L P A P E R
Cu1.5PMo12O40‐catalyzed condensation cyclization for the
synthesis of substituted pyrazoles
Guo‐Ping Yang1,3 | Xing He1 | Bing Yu2
| Chang‐Wen Hu1
1 Key Laboratory of Cluster Science of
A convenient and direct approach has been developed for the preparation of
pyrazole derivatives by the condensation cyclization of hydrazines/hydrazide
and 1,3‐diketones in the presence of Cu1.5PMo12O40 (0.33 mol%) under mild
conditions (r.t.‐60 °C, 10–30 min). Notably, the reaction was found to be scal-
able as 99% yield was obtained when the reaction was performed at a 5‐mmol
scale. This solvent‐free and halogen‐free catalytic system represents an effec-
tive economic and environmentally friendly method for the construction of
pyrazoles.
Ministry of Education, Beijing Key
Laboratory of Photoelectronic/
Electrophotonic, School of Chemistry and
Chemical Engineering, Beijing Institute of
Technology, Beijing 100081, P. R. China
2 College of Chemistry and Molecular
Engineering, Zhengzhou University,
Zhengzhou 450001, Henan Province, P. R.
China
3 China Academy of Engineering Physics,
P. R. China
KEYWORDS
Correspondence
condensation reaction, copper, hydrazine, polyoxometalates, pyrazole
Bing Yu, College of Chemistry and
Molecular Engineering, Zhengzhou
University, Zhengzhou 450001, Henan
Province, P. R. China.
Email: bingyu@zzu.edu.cn
Chang‐Wen Hu, Key Laboratory of
Cluster Science of Ministry of Education,
Beijing Key Laboratory of
Photoelectronic/Electrophotonic, School
of Chemistry and Chemical Engineering,
Beijing Institute of Technology, Beijing
100081, P. R. China.
Email: cwhu@bit.edu.cn
Funding information
National Natural Science Foundation of
China, Grant/Award Numbers: 21501010
and 21671019; 973 Program, Grant/Award
Number: 2014CB932103; the 111 Project,
Grant/Award Number: B07012
1 | INTRODUCTION
Razaxaban, and Rimonabant, which are valuable biologi-
cally and pharmaceutically active organic molecules.
Nitrogen‐containing heterocycles have attracted wide-
spread attention in the field of synthetic organic chemis-
try due to their wide and diverse applications in
pharmaceutical and agrochemical fields.[1] Particularly,
the pyrazole ring is a prominent structure motif that
was found as the core structure of numerous drugs,[2]
such as Celecoxib, Deracoxib, Penthiopyrad, Lonazolac,
Due to the important of the pyrazoles, it is therefore
not surprising that many synthetic methods have been
developed for the construction of pyrazole scaffold.[3]
For instance, the pyrazole ring can be synthesized via
the reaction of hydrazines with unsaturated aldehydes/
ketones,[4] or 1,3‐dicarbonyl compounds,[5] 1,3‐dipolar
cycloaddition of diazo compounds with alkenes,[6]
Appl Organometal Chem. 2018;e4532.
wileyonlinelibrary.com/journal/aoc
© 2018 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.4532

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YANG ET AL.
TABLE 1 Optimization of the reaction conditionsa
alkynes,[7] or 1,3‐dicarbonyl compounds,[8] oxidative cou-
pling of enaminones and nitriles,[9] etc. Among these
methods hitherto developed, the most generally useful
one is based on the condensation‐cyclization reaction of
hydrazines and 1,3‐dicarbonyl compounds. For example,
in 2004, the Wang's group[5] reported the sulfuric acid
catalyzed condensation cyclization between hydrazines
and 1,3‐diketones, affording pyrazole derivatives. More-
over, various protocols employed microwave,[10] or acidic
catalysts,e.g., Sc (OTf)3,[11] polystyrene supported sulfonic
acid,[12] layered zirconium sulfophenyl phosphonate
catalysis,[13] were reported to be efficient for the prepara-
tion pyrazoles. Each of those reported procedures has its
own merit, meanwhile, those methods suffer from vari-
ous drawbacks such as harsh or sensitive reaction condi-
tions, difficulties of catalyst preparation, long reaction
time, inconvenient operation, etc. Therefore, there is a
great need to develop a more convenient operation, much
greener, and suitable for industrial production methods.
In the course of our continuing efforts in developing
polyoxometalate‐catalyzed reactions,[14] we herein report
a practical, high efficiency, and environmentally benign
protocol for pyrazoles synthesis by employing
Cu1.5PMo12O40 (0.33 mol%) as catalyst under mild condi-
tions (Scheme 1).
Catalyst loading
Entry
Catalyst
(mol%)
Yieldb [%]
1
‐
‐
34
66
2
Zn (OAc)2
3
3
AlCl3·6H2O
InCl3
3
72
4
3
75
5
Cu (OTf)2
3
84
6
CH3COOH
H3PMo12O40
CuSO4·5H2O
Cu (NO3)2·3H2O
CuCl2·2H2O
CuBr·DMS
Cu (acac)2
3
56
7
1
56
8
3
88
9
3
90
10
11
12
13
14
15
16c
3
88
3
83
3
75
Cu (OAc)2·2H2O
Cu1.5PMo12O40
Cu1.5PMo12O40
Cu1.5PMo12O40
3
65
2
>99
>99
>99
0.33
0.33
2 | RESULTS AND DISCUSSION
aReaction conditions: hydrazide 1a (1 mmol), 1,3‐diketone 2a (1 mmol), cat-
alyst, solvent‐free, r.t., 15 min. Ts = p‐toluenesulfonyl; DMS = dimethyl
sulphide.
To optimize the reaction conditions, we studied the
condensation of p‐toluenesulfonyl hydrazide 1a with
acetylacetone 2a using various catalysts. As shown in
Table 1, the reaction without any catalyst led to the desired
pyrazole 3a in yield of 34% at room temperature for 15 min
(entry 1). Then we attempted to use some Lewis acids,
such as Zn (OAc)2, AlCl3·6H2O, InCl3, and Cu (OTf)2,
and Bronsted acids, i.e. CH3COOH and H3PMo12O4 to
catalyze the reaction under identical conditions. Accord-
ingly, the desired product 3a was obtained in yields of
66%, 72%, 75%, 84%, 56%, and 56% (entries 2–7). From these
results, we can speculate that the catalytic activity of
copper‐based catalyst is probably better than others. Subse-
quently, a series of copper salts like CuSO4·5H2O, Cu
(NO3)2·3H2O, CuCl2·2H2O, CuBr·DMS, Cu (acac)2, Cu
(OAc)2·2H2O were surveyed as catalyst for the model reac-
tion. All those copper salts showed good activities (65–90%
bThe yields were determined by GC with biphenyl as the internal standard.
cThe time is 10 min.
yields, entries 8–13). Among these, Cu (NO3)2·3H2O was
the most promising and delivered the desired product 3a
in 90% yield, indicating that the counter anion of copper
catalyst has a profound impact on the activity (entry 9).
However, from an industrial point of view, scalability and
catalyst selectivity are significantly important factors;
therefore, a more active catalyst is still required.
It is known that [PMo12O40]3− is an excellent soft base
anion, which might enhance the catalytic activity of cop-
per ion.[15] Then the polyacid salt Cu1.5PMo12O40 was
synthesized as a catalyst for the condensation reaction
of 1a and 2a.[16] To our delight, the condensation reaction
provided the product 3a in almost quantitative yield cata-
lyzed by 2 mol% of Cu1.5PMo12O40 (entry 14). To evaluate
the catalyst efficiency, the catalyst loadings and reaction
time were further decreased (entries 15 and 16). Finally,
the target pyrazole product 3a could be obtained in excel-
lent yield by using 0.33 mol% of Cu1.5PMo12O40 as cata-
lyst at room temperature for 10 min (entry 16).
With these optimized conditions in hand, we next
focused our attention on substrate scope to determine
SCHEME 1 Condensation‐cyclization reaction of hydrazines and
1,3‐dicarbonyl compounds

YANG ET AL.
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TABLE 2 Substrate scope of the condensation reactiona
aReaction conditions: hydrazine (1 mmol), 1,3‐diketone (1 mmol), Cu1.5PMo12O40 (0.33 mol%), solvent‐free. Isolated yields were given.
the generality of this procedure. As summarized in
Table 2, a variety of pyrazole derivatives were constructed
by the condensation of hydrazines and 1,3‐diketones. The
products 3a and 3b, from TsNHNH2 and acetylacetones,
were obtained in almost quantitative yields at room tem-
perature for 10 min and 15 min, respectively. As for the
electron withdrawing group containing substrate,e.g., 3‐
chloro‐2,4‐pentanedione, longer reaction time (30 min)
and elevated temperature (60 °C) were necessary to
achieve an excellent yield of 3c. The reaction of elec-
tron‐rich or electron‐poor benzohydrazides showed high
reactivity to afford the corresponding pyrazoles 3d‐k in
good to excellent yields (83–98%). However, it is obvious
that the substrates with electron‐withdrawing substitu-
ents displayed lower reactivities. Therefore, 60 °C was
generally required. Moreover, the aromatic hydrazine
derivatives, such as phenylhydrazine and (2,4‐
dinitrophenyl) hydrazine, were also worked well in this
protocol, providing the corresponding product 3 l‐p in
excellent yields. The simple hydrazine hydrate showed
good reactivity for the construction of pyrazole 3q‐s.
Unfortunately, the heterocyclic hydrazine was not suitable
for this procedure even at 60 °C (3 t and 3u), probably due
to the coordination effect of heteroatom and copper,
which may poison the catalyst. Unfortunately, the unsym-
metrical 1,3‐dicarbonyl compound ethyl 3‐oxo‐3‐
phenylpropanoate did not show any reactivity with 1a in
the presence of Cu1.5PMo12O40 at r.t. or 60 °C for 30 min.
Interestingly, the reaction of hydrazine hydrate and 3‐
chloro‐2,4‐pentanedione (2c) delivered different products
by using different equivalents of hydrazine hydrate
under room temperature. As shown in Scheme 2, the

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YANG ET AL.
an important role in the cyclization of 3p’ to form the
pyrazole 3p (Scheme 4).
3 | CONCLUSIONS
In conclusion, we have presented an efficient protocol for
the condensation reaction of hydrazines/hydrazide and
1,3‐diketones to synthesize pyrazoles employing
Cu1.5PMo12O40 as a halogen‐free catalyst under mild con-
ditions. Various pyrazoles were constructed in excellent
yields. Furthermore, the reaction was proved to be scal-
able at a gram scale with excellent yields. The reaction
proceeded with low catalyst loadings and short reaction
times, which represents an economic and environmen-
tally friendly method.
SCHEME
hydrazine hydrate
2
Reaction of 3‐chloro‐2,4‐pentanedione and
condensation product 3v was obtained in 98% yield when
the 1.0 equivalent of hydrazine hydrate was applied;
while the excess amount of hydrazine hydrate (2.5 equiv.)
was employed, the condensation‐dehalogenation product
3q was observed in 94% yield. We surmised that the con-
densation was fast and efficient to form 3v, then the
excess amount of hydrazine hydrate could act as a base
for the dehalogenation of 3v providing 3q as product.
Notably, this procedure is scalable and practical.
Almost quantitative yields were obtained when the reac-
tion was conducted on gram scale under room temperature
by the catalysis of Cu1.5PMo12O40 (0.33 mol%) albeit with
higher temperature or longer reaction time (Scheme 3).
To gain further insights into this transformation, the
blank experiment of (2,4‐dinitrophenyl) hydrazine 1f
and 3‐methylpentane‐2,4‐dione 2b was conducted with
Cu1.5PMo12O40 catalyst at room temperature. The con-
densation product 3p’ was detected by GC–MS as major
product, while 3p was the minor product (see the
4 | EXPERIMENTAL SECTION
4.1 | Preparation of the catalyst[16]
The aqueous solution of H3PMo12O40 was neutralized by
adding a required amount of Ba (OH)2·8H2O (1.5 equiv.),
and then the required amount of CuSO4·5H2O (1.5
equiv.) was added. After eliminating the formed BaSO4
precipitate by filtration, the aqueous Cu1.5PMo12O40 solu-
tion was obtained. After bubbling nitrogen to the
resulting solution, water was evaporated under reduced
pressure. The obtained compound was dried under vac-
uum at 60 °C overnight, and then characterized by FT‐
IR and ESI‐MS (see the Supporting Information).
Supporting
Information).
Compared
with
the
Cu1.5PMo12O40‐catalyzed reaction at 60 °C, it was clear
that the pyrazole was constructed via a step wised con-
densation‐cyclization reaction, and the catalyst played
4.2 | Typical procedure of the
Cu1.5PMo12O40 catalyzed condensation
reaction
To an 8‐mL reaction vial, p‐toluenesulfonyl hydrazide
(1 mmol), acetylacetone (1 mmol), Cu1.5PMo12O40
(0.33 mol%) were added. Then the reaction was carried
out in screw cap vials with a Teflon seal at r.t. for the
desired time. After reaction, the mixture was purified by
SCHEME 3 Gram scale reactions
SCHEME 4 Control experiments

YANG ET AL.
5 of 7
column chromatography (petroleum ether/EtOAc) to
afford the desired products.
131.26, 127.80, 117.48, 12.55, 12.39, 7.72; EI‐MS: m/z (%)
=105.2 (100), 214.2 (35) [M+].
4.3 | Characterization Data of the Product
4.3.6 | (4‐chloro‐3,5‐dimethyl‐1H‐pyrazol‐
1‐yl)(phenyl)methan‐one (3f)
4.3.1 | 3,5‐dimethyl‐1‐tosyl‐1H‐pyrazole
(3a)
1H NMR (400 MHz, CDCl3): δ (ppm) 7.95 (d, J = 8 Hz,
2H), 7.58 (t, J = 8 Hz, 1H), 7.46 (t, J = 8 Hz, 2H), 2.64
(s, 3H), 2.26 (s, 3H); 13C NMR (100.6 MHz, CDCl3): δ
(ppm) 167.90, 149.57, 140.35, 132.74, 132.50, 131.38,
127.96, 114.86, 12.35, 11.81; EI‐MS: m/z (%) =105.2
(100), 234.1 (24) [M+].
1H NMR (400 MHz, CDCl3): δ (ppm) 7.82 (d, J = 8.0 Hz,
2H), 7.30 (d, J = 8.0 Hz, 2H), 5.89 (s, 1H), 2.49 (s, 3H),
2.40 (s, 3H), 2.19 (s, 3H); 13C NMR (100.6 MHz, CDCl3):
δ (ppm) 153.40, 145.18, 144.08, 135.37, 129.90, 127.55,
110.77, 21.65, 13.83, 13.10; EI‐MS: m/z (%) =186.2 (100),
250.1 (1) [M+].
4.3.7 | (2‐chlorophenyl)(3,5‐dimethyl‐1H‐
pyrazol‐1‐yl) methanone (3 g)
1H NMR (400 MHz, CDCl3): δ (ppm) 7.33–7.79 (m, 4H),
6.05 (s, 1H), 2.66 (s, 3H), 2.17 (s, 3H); 13C NMR
(100.6 MHz, CDCl3): δ (ppm) 167.43, 153.23, 144.49,
135.12, 131.70, 131.21, 129.71, 129.36, 126.35, 111.78,
14.25, 13.94; EI‐MS: m/z (%) =199.2 (100), 234.1 (0) [M+].
4.3.2 | 3,4,5‐trimethyl‐1‐tosyl‐1H‐pyrazole
(3b)
1H NMR (400 MHz, CDCl3): δ (ppm) 7.80 (d, J = 8.0 Hz,
2H), 7.28 (d, J = 8.0 Hz, 2H), 2.39 (s, 6H), 2.14 (s, 3H),
1.83 (s, 3H); 13C NMR (100.6 MHz, CDCl3): δ (ppm)
153.69, 144.86, 139.60, 135.62, 129.82, 127.50, 117.20,
21.65, 12.44, 11.33, 8.02; EI‐MS: m/z (%) = 200.2 (100),
264.1 (10) [M+].
4.3.8 | (2‐chlorophenyl)(3,4,5‐trimethyl‐
1H‐pyrazol‐1‐yl)methan‐one (3 h)
1H NMR (400 MHz, CDCl3): δ (ppm) 7.31–7.46 (m, 4H),
2.59 (s, 3H), 2.11 (s, 3H), 1.94 (s, 3H); 13C NMR
(100.6 MHz, CDCl3): δ (ppm) 167.25, 153.68, 139.76,
135.52, 131.56, 130.99, 129.63, 129.25, 126.33, 118.30,
12.47, 7.70; EI‐MS: m/z (%) = 213.2.2 (100), 248.1 (1) [M+].
4.3.3 | 4‐chloro‐3,5‐dimethyl‐1‐tosyl‐1H‐
pyrazole (3c)
1H NMR (400 MHz, CDCl3): δ (ppm) 7.83 (d, J = 7.6 Hz,
2H), 7.20 (d, J = 7.6 Hz, 2H), 2.49 (s, 3H), 2.42 (s, 3H),
2.21 (s, 3H); 13C NMR (100.6 MHz, CDCl3): δ (ppm)
150.91, 145.70, 139.31, 134.76, 130.09, 127.79, 113.78,
21.72, 11.92, 11.26; EI‐MS: m/z (%) = 91.2 (100), 284.1
(11) [M+].
4.3.9 | (4‐chloro‐3,5‐dimethyl‐1H‐pyrazol‐
1‐yl)(2‐chlorophenyl)‐methanone (3i)
1H NMR (400 MHz, CDCl3): δ (ppm) 7.34–7.46 (m, 4H),
2.67 (s, 3H), 2.18 (s, 3H); 13C NMR (100.6 MHz, CDCl3):
δ (ppm) 167.01, 150.66, 134.28, 131.82, 131.50, 129.75,
129.44, 126.41, 115.52, 12.24, 11.85; EI‐MS: m/z
(%) = 139.1 (100), 268.1 (1) [M+].
4.3.4 | (3,5‐dimethyl‐1H‐pyrazol‐1‐yl)(phe-
nyl) methanone (3d)
1H NMR (400 MHz, CDCl3): δ (ppm) 7.99 (d, J = 8 Hz,
2H), 7.56 (t, J = 8 Hz, 1H), 7.46 (t, J = 8 Hz, 2H), 6.06
(s, 1H), 2.64 (s, 3H), 2.25 (s, 3H); 13C NMR (100.6 MHz,
CDCl3): δ (ppm) 168.45, 152.16, 145.11, 133.36, 132.45,
131.38, 127.87, 111.11, 14.36, 13.90; EI‐MS: m/z (%)
=105.2 (100), 200.1 (39) [M+].
4.3.10 | (3,5‐dimethyl‐1H‐pyrazol‐1‐yl)(4‐
methoxyphenyl)methan‐one (3j)
4.3.5 | phenyl(3,4,5‐trimethyl‐1H‐pyrazol‐
1‐yl) methanone (3e)
1H NMR (400 MHz, CDCl3): δ (ppm) 7.96 (d, J = 7.6 Hz,
2H), 7.54 (t, J = 7.2 Hz, 1H), 7.45 (t, J = 7.2 Hz, 2H), 2.56
(s, 3H), 2.20 (s, 3H), 1.97 (s, 3H); 13C NMR (100.6 MHz,
CDCl3): δ (ppm) 168.36, 152.49, 140.45, 133.71, 132.19,
1H NMR (400 MHz, CDCl3): δ (ppm) 8.05 (d, J = 8.0 Hz,
2H), 6.95 (d, J = 8.0 Hz, 2H), 6.04 (s, 1H), 3.86 (s, 3H),
2.61 (s, 3H), 2.25 (s, 3H); 13C NMR (100.6 MHz, CDCl3):
δ (ppm) 167.54, 163.20, 151.67, 144.99, 134.00, 125.35,
113.28, 110.73, 55.47, 14.27, 13.88; EI‐MS: m/z (%)
=135.2 (100), 230.2 (29) [M+].

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YANG ET AL.
115.86, 11.99, 10.40, 8.22; EI‐MS: m/z (%) = 276.1 (100)
4.3.11 | (4‐methoxyphenyl)(3,4,5‐
trimethyl‐1H‐pyrazol‐1‐yl)meth‐anone (3 k)
[M+].
1H NMR (400 MHz, CDCl3): δ (ppm) 8.02 (d, J = 8.0 Hz,
2H), 6.94 (d, J = 7.6 Hz, 2H), 3.87 (s, 3H), 2.53 (s, 3H),
2.21 (s, 3H), 1.96 (s, 3H); 13C NMR (100.6 MHz, CDCl3):
δ (ppm) 167.51, 163.01, 151.97, 140.42, 133.85, 125.70,
117.08, 113.22, 55.45, 12.48, 12.37, 7.74; EI‐MS: m/z (%)
=135.2 (100), 244.2 (33) [M+].
4.3.17 | 3,5‐dimethyl‐1H‐pyrazole (3q)
1H NMR (400 MHz, CDCl3): δ (ppm) 9.88 (s, 1H), 5.82 (s,
1H), 2.27 (s, 6H); 13C NMR (100.6 MHz, CDCl3): δ (ppm)
144.46, 104.14, 12.23; EI‐MS: m/z (%) = 96.1 (100) [M+].
4.3.12 | 3,5‐dimethyl‐1‐phenyl‐1H‐pyrazole
4.3.18 | 3,4,5‐trimethyl‐1H‐pyrazole(3r)
(3 l)
1H NMR (400 MHz, CDCl3): δ (ppm) 9.56 (s, 1H), 2.18 (s,
6H), 1.90 (s, 3H); 13C NMR (100.6 MHz, CDCl3): δ (ppm)
142.10, 110.59, 103.91, 10.79, 7.54; EI‐MS: m/z (%) = 109.1
(100), 110.1 (83) [M+].
1H NMR (400 MHz, CDCl3): δ (ppm) 7.33–7.43 (m, 5H),
5.99 (s, 1H), 2.30 (s, 6H); 13C NMR (100.6 MHz, CDCl3):
δ (ppm) 148.95, 139.96, 139.35, 128.97, 127.21, 124.75,
106.90, 13.52, 12.38; EI‐MS: m/z (%) = 172.2 (100) [M+].
4.3.19 | 3,5‐diphenyl‐1H‐pyrazole (3 s)
4.3.13 | 3,4,5‐trimethyl‐1‐phenyl‐1H‐
1H NMR (400 MHz, CDCl3): δ (ppm) 11.01 (s, 1H), 7.33–
7.75 (m, 10H), 6.85 (d, J = 0.8 Hz, 1H); 13C NMR
(100.6 MHz, CDCl3): δ (ppm) 170.18, 147.71, 130.27,
127.85, 127.22, 124.58, 99.07, 59.40, 20.04, 13.17; EI‐MS:
m/z (%) =220.2 (100) [M+].
pyrazole (3 m)
1H NMR (400 MHz, CDCl3): δ (ppm) 7.29–7.42 (m, 5H),
2.25 (s, 3H), 2.21 (s, 3H) 1.98 (s, 3H); 13C NMR
(100.6 MHz, CDCl3): δ (ppm) 148.08, 140.16, 136.07,
128.97, 126.97, 124.68, 113.25, 11.89, 10.97, 8.21; EI‐MS:
m/z (%) = 186.2 (100) [M+].
4.3.20 | 4‐chloro‐3, 5‐dimethyl‐1H‐pyrazole
(3v)
4.3.14 | 4‐chloro‐3,5‐dimethyl‐1‐phenyl‐1H‐
pyrazole (3n)
1H NMR (400 MHz, CDCl3): δ (ppm) 10.54 (s, 1H), 2.25 (s,
6H); 13C NMR (100.6 MHz, CDCl3): δ (ppm) 141.01,
107.89, 10.38; EI‐MS: m/z (%) =130.1 (100) [M+].
1H NMR (400 MHz, CDCl3): δ (ppm) 7.35–7.48 (m, 5H),
2.30 (s, 6H); 13C NMR (100.6 MHz, CDCl3): δ (ppm)
146.06, 139.79, 135.70, 129.18, 127.72, 124.56, 109.83,
11.42, 10.84; EI‐MS: m/z (%) = 206.1 (100) [M+].
ACKNOWLEDGMENTS
We thank the Natural Science Foundation of China
(21501010, 21671019), 973 Program (2014CB932103) and
the 111 Project (B07012) for financial support.
4.3.15 | 1‐(2,4‐dinitrophenyl)‐3,5‐dimethyl‐
1H‐pyrazole (3o)
1H NMR (400 MHz, CDCl3): δ (ppm) 8.80 (s, 1H), 8.53 (d,
J = 8.8 Hz, 1H), 7.70 (d, J = 8.8 Hz, 1H), 6.10 (s, 1H), 2.26
(d, J = 6 Hz, 6H); 13C NMR (100.6 MHz, CDCl3): δ (ppm)
152.39, 146.24, 145.67, 140.88, 137.97, 129.35, 127.31,
121.02, 108.91, 13.50, 11.63; EI‐MS: m/z (%) = 262.1
(100) [M+].
ORCID
Bing Yu http://orcid.org/0000-0002-2423-1212
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4.3.16 | 1‐(2,4‐dinitrophenyl)‐3,4,5‐
trimethyl‐1H‐pyrazole (3p)
1H NMR (400 MHz, CDCl3): δ (ppm) 8.77 (s, 1H), 8.50 (d,
J = 8.8 Hz, 1H), 7.66 (d, J = 8.8 Hz, 1H), 2.19 (s, 6H), 1.99
(s, 3H); 13C NMR (100.6 MHz, CDCl3): δ (ppm) 152.01,
145.73, 145.29, 138.21, 137.04, 128.87, 127.24, 121.06,

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SUPPORTING INFORMATION
Additional supporting information may be found online
in the Supporting Information section at the end of the
article.
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How to cite this article: Yang G‐P, He X, Yu B,
Hu C‐W. Cu1.5PMo12O40‐catalyzed condensation
cyclization for the synthesis of substituted
pyrazoles. Appl Organometal Chem. 2018;e4532.
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