A rapid, efficient, and high-yielding synthesis of 4,4′-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ol) derivatives catalyzed by 12-tungstophosphoric acid (H3PW12O40)

Article abstract of DOI:10.1007/s11164-014-1896-y

A fast, green, and efficient method for high-yielding synthesis of 4,4′-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols) by one-pot reaction of two equivalents of 3-methyl-1H-pyrazol-5(4H)-one with aryl aldehydes, using 12-tungstophosphoric acid (H₃PW₁₂O₄₀) as an effective and inorganic catalyst is described. The catalyst is inexpensive and readily available and can be recovered conveniently and reused efficiently such that a considerable catalytic activity still could be achieved after the tenth run. Compared to the other methods, the present methodology offers several advantages such as excellent yields, short reaction times, and mild reaction conditions with an easy work-up.

Full text of DOI:10.1007/s11164-014-1896-y

Res Chem Intermed
DOI 10.1007/s11164-014-1896-y
A rapid, efficient, and high-yielding synthesis of
4,40-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ol)
derivatives catalyzed by 12-tungstophosphoric acid
(H3PW12O40)
•
Asieh Vafaee Abolghasem Davoodnia Mehdi Pordel
•
Received: 18 September 2014 / Accepted: 10 December 2014
Ó Springer Science+Business Media Dordrecht 2015
Abstract A fast, green, and efficient method for high-yielding synthesis of 4,40-
(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols) by one-pot reaction of two equiva-
lents of 3-methyl-1H-pyrazol-5(4H)-one with aryl aldehydes, using 12-tungsto-
phosphoric acid (H3PW12O40) as an effective and inorganic catalyst is described.
The catalyst is inexpensive and readily available and can be recovered conveniently
and reused efficiently such that a considerable catalytic activity still could be
achieved after the tenth run. Compared to the other methods, the present method-
ology offers several advantages such as excellent yields, short reaction times, and
mild reaction conditions with an easy work-up.
Keywords 4,40-(Arylmethylene)bis(3-methyl-1H-pyrazol-5-ols) ꢀ 3-Methyl-1H-
pyrazol-5(4H)-one ꢀ Heteropoly acid ꢀ 12-Tungstophosphoric acid
Introduction
Pyrazoles, especially 1H-pyrazol-5(4H)-one derivatives including 4,40-(arylmethyl-
ene)bis(1H-pyrazol-5-ols), are an important class of heterocyclic compounds with
diverse and interesting biological activities. These compounds are reported to
possess significant antipyretic [1], antidepressant [2], antiviral [3], antifungal [4],
antitumor [5], and anti-inflammatory [6] activities. Moreover, a number of these
compounds have been considered as fungicides [7], pesticides, and dyestuffs [8, 9],
and as the chelating and extracting reagents for different metal ions [10]. Some of
the pyrazolone derivatives are now included in many commercialized drugs for
brain ischemia [11] and myocardial ischemia [12]. Furthermore, pyrazoles are not
only of interest as intermediates in chemical synthesis but also as efficient analytical
A. Vafaee ꢀ A. Davoodnia (&) ꢀ M. Pordel
Department of Chemistry, Mashhad Branch, Islamic Azad University, Mashhad, Iran
e-mail: adavoodnia@yahoo.com; adavoodnia@mshdiau.ac.ir
123

A. Vafaee et al.
regents in the complexation of transition-metal ions [13]. On the other hand, 4,40-
(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols) are applied as important intermedi-
ates for the synthesis of fused heterocycles such as 1H-pyrano[2,3-c:6,5-c’]dipy-
razoles [14] and dipyrazolo[3,4-c:30,40-f][1,2]diazepines [15]. Additionally, some
bispyrazoles are used as ligands for the synthesis of organometallic palladium(II)
complexes [16].
´
In spite of extensive application of 4,4-(arylmethylene)bis(1H-pyrazol-5-ols), a
few methods have been reported for the preparation of these interesting compounds.
The conventional chemical approach to the synthesis of these compounds involves
the successive Knoevenagel synthesis of the corresponding arylidenepyrazolones in
first step and its Michael reaction with 1-phenyl-3-methyl-1H-pyrazol-5(4H)-one in
´
second step [17]. Nevertheless, one-pot synthetic methods for the preparation of 4,4-
(arylmethylene)bis(1H-pyrazol-5-ols) are known and employ the tandem Knoeve-
nagel-Michael reaction of aryl aldehydes with two equivalents of 1,3-disubstituted-
1H-pyrazol-5(4H)-ones performed using various catalysts such as 1,3,5-tris(hy-
drogensulfato)benzene [18], 3-aminopropylated silica gel [19], silica-bonded ionic
liquid [20], silica-bonded N-propylpiperazine sulfamic acid [21], 2-hydroxy
ethylammonium propionate [22], sodium dodecyl sulfate [23], sulfuric acid ([3-
(3-silicapropyl)sulfanyl]propyl)ester [24], poly(ethylene glycol)-bound sulfonic
acid [25], [HMIM]HSO4 under ultrasonic irradiation [26], phosphomolybdic acid
[27], LiOH.H2O [28], cellulose sulfuric acid [29], silica-bonded N-propyltriethy-
lenetetramine [30], silica-bonded S-sulfonic acid [31], and pyridine trifluoroacetate
[32]. Catalysis by piperidine in ethanolic solution reported by Singh et al. [33]
afforded the desired products in poor 15–35 % yields. The uncatalyzed reactions for
the synthesis of these compounds have been also reported in poly(ethylene glycol)-
400 (PEG-400) as reaction media at 110 °C [34] or in refluxing water [35]. Even
´
though these uncatalyzed reactions afford the corresponding 4,4-(arylmethyl-
ene)bis(1H-pyrazol-5-ols) in 72–94 % yields, the reactions require long reaction
times (2–8 h) for completion. Furthermore, Elison et al. [36] applied the
electrocatalytic procedure in the presence of sodium bromide as electrolyte to the
synthesis of these compounds. However, many of these methodologies are not
entirely satisfactory and suffer from limitations such as long reaction times,
unsatisfactory yields, and using ultrasonic irradiation or electrocatalytic procedure
for accelerated synthesis. Thus, the development of an alternate milder and clean
procedure is highly demanding for the synthesis of 4,40-(arylmethylene)bis(1H-
pyrazol-5-ols), which surpasses those limitations.
The use of Keggin-type heteropolyacids (HPAs) as homogeneous or heteroge-
neous catalysts in organic synthesis has been developed as a result of their several
advantages, such as environmental compatibility, reusability, non-corrosiveness,
and relative lack of disposal problems, which make them economically and
environmentally attractive [37, 38]. Being stronger acids, HPAs, especially
12-tungstophosphoric acid (H3PW12O40), generally exhibit higher catalytic activ-
ities than conventional catalysts, such as mineral acids, ion-exchange resins,
zeolites, etc. [39, 40]. On the other hand, the H3PW12O40 is highly soluble in water
and polar organic solvents, such as lower alcohols and carboxylic acids, and
insoluble in hydrocarbons. To the best of our knowledge, there are no examples on
123

Synthesis of 4,40-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols)
the use of H3PW12O40 as homogeneous catalyst for the synthesis of 4,40-
(arylmethylene)bis(1H-pyrazol-5-ols). On the other hand, only two papers have
been reported for the synthesis of 4,40-(arylmethylene)bis(1-unsubstituted-1H-
pyrazol-5-ols) [22, 23].
As part of our research program directed towards the development of highly
expedient methods using reusable catalysts for the synthesis of organic compounds
[41–44], we report here our results on the rapid, efficient, and high-yielding
synthesis of 4,40-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols) by one-pot reac-
tion of two equivalents of 3-methyl-1H-pyrazol-5(4H)-one [45], with aryl aldehydes
in the presence of H3PW12O40, the strongest HPA in the Keggin series [39], as a
homogeneous catalyst (Scheme 1).
Experimental
Melting points were recorded using a Stuart SMP3 melting point apparatus. The FT-
IR spectra of the products were obtained with KBr disks, using a Tensor 27 Bruker
1
spectrophotometer. The H NMR and 13C-NMR spectra were recorded using a
Bruker 400 spectrometer at 400- and 100-MHz frequencies, respectively.
General procedure for the synthesis of 4,40-(arylmethylene)bis(3-methyl-1H-
pyrazol-5-ols) 3a–3j
A mixture of 3-methyl-1H-pyrazol-5(4H)-one 1 (2 mmol), an aryl aldehyde 2a-2j
(1 mmol), and H3PW12O40 (10 mol % based on aryl aldehyde) in ethanol (2 ml)
was heated under reflux for 10–60 min. During the procedure, the reaction was
monitored by TLC. Upon completion of the transformation, the reaction mixture
was cooled to room temperature. This resulted in the precipitation of the product,
which was collected by filtration, washed repeatedly with cold water and
recrystallized from ethanol to give products 3a–3j in high yields.
Scheme 1 H3PW12O40 catalyzed synthesis of 4,40-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols)
123

A. Vafaee et al.
1
Selected H and 13C NMR and FT-IR data
1
4,40-(Phenylmethylene)bis(3-methyl-1H-pyrazol-5-ol) 3a H NMR (400 MHz, d6-
DMSO): d 2.08 (s, 6H), 4.83 (s, 1H), 7.08–7.17 (m, 3H), 7.19–7.25 (m, 2H), 11.24
(br., 4H); 13C-NMR (100 MHz, d6-DMSO): d 10.8, 33.2, 104.7, 125.9, 127.9, 128.2,
140.2, 143.8, 161.5; IR (KBr disc): t 3,296, 2971, 2,500–3,500, 1,614, 1,522, 1,492,
1,380, 1,275, 1,214, 1,050, 774, 718 cm-1
.
4,40-((4-Chlorophenyl)methylene)bis(3-methyl-1H-pyrazol-5-ol) 3b 1H NMR
(400 MHz, d6-DMSO): d 2.08 (s, 6H), 4.82 (s, 1H), 7.13 (d, J = 8.4 Hz, 2H),
7.27 (d, J = 8.4 Hz, 2H), 11.33 (br., 4H); 13C-NMR (100 MHz, d6-DMSO): d 10.8,
32.6, 104.3, 128.1, 129.8, 130.4, 140.1, 142.8, 161.4; IR (KBr disc): t 2,400–3,500,
1,601, 1,532, 1,491, 1,203, 1,172, 1,091, 1,015, 852, 799, 767 cm-1
.
4,40-((4-Bromophenyl)methylene)bis(3-methyl-1H-pyrazol-5-ol) 3f 1H NMR
(400 MHz, d6-DMSO): d 2.18 (s, 6H), 4.86 (s, 1H), 7.07 (d, J = 8.4 Hz, 2H),
7.42 (d, J = 8.4 Hz, 2H), 12.17 (br., 4H); 13C-NMR (100 MHz, d6-DMSO): d 10.7,
32.2, 104.5, 119.4, 130.0, 131.2, 141.9, 142.4, 161.1; IR (KBr disc): t 3,186,
2,400–3,500, 1,595, 1,485, 1,144, 1,079, 1,010, 979, 898, 817 cm-1
.
4,40-((4-Methylphenyl)methylene)bis(3-methyl-1H-pyrazol-5-ol) 3g 1H NMR
(400 MHz, d6-DMSO): d 2.13 (s, 6H), 2.23 (s, 3H), 4.79 (s, 1H), 6.95–7.05 (m,
4H), 11.83 (br., 4H); 13C-NMR (100 MHz, d6-DMSO): d 10.8, 21.0, 32.5, 105.0,
127.7, 128.9, 134.9, 140.3, 141.1, 161.4; IR (KBr disc): t 3,126, 2,922,
2,400–3,500, 1,599, 1,512, 1,449, 1,080, 961, 898, 820 cm-1
.
4,40-((4-Methoxyphenyl)methylene)bis(3-methyl-1H-pyrazol-5-ol) 3h 1H NMR
(400 MHz, d6-DMSO): d 2.16 (s, 6H), 3.69 (s, 3H), 4.80 (s, 1H), 6.79 (d,
J = 8.4 Hz, 2H), 7.03 (d, J = 8.4 Hz, 2H), 12.32 (br., 4H); 13C-NMR (100 MHz,
d6-DMSO): d 10.7, 32.0, 55.4, 105.2, 113.7, 128.7, 135.0, 141.6, 157.8, 161.2; IR
(KBr disc): t 3,205, 2,930, 2,400–3,500, 1,603, 1,510, 1,463, 1,247, 1,178, 1,080,
1,033, 980, 898, 822 cm-1
4,40-(Pyridin-2-ylmethylene)bis(3-methyl-1H-pyrazol-5-ol)
.
3i
1H
NMR
(400 MHz, d6-DMSO): d 2.12 (s, 6H), 5.04 (s, 1H), 7.22–7.30 (m, 1H), 7.37 (d,
J = 8.0 Hz, 1H), 7.77 (td, J = 7.6, 1.6 Hz, 1H), 8.46 (d, J = 4.5 Hz, 1H), 11.81
(br., 4H); 13C-NMR (100 MHz, d6-DMSO): d 10.8, 36.2, 103.6, 122.2, 122.9, 138.0,
141.0, 148.0, 160.7, 161.9; IR (KBr disc): t 3,174, 2,927, 2,400–3,500, 1,608,
1,528, 1,471, 1,080, 980, 897, 820 cm-1
.
4,40-(Thiophen-2-ylmethylene)bis(3-methyl-1H-pyrazol-5-ol) 3j 1H NMR
(400 MHz, d6-DMSO): d 2.12 (s, 6H), 4.99 (s, 1H), 6.58–6.62 (m, 1H), 6.85 (dd,
J = 4.8, 3.6 Hz, 1H), 7.24 (d, J = 4.8 Hz, 1H), 11.47 (br., 4H); 13C-NMR
(100 MHz, d6-DMSO): d 10.7, 29.3, 104.9, 124.2, 124.3, 126.9, 140.3, 149.1, 161.2;
IR (KBr disc): t 3,373, 3,104, 2,925, 2,300–3,500, 1,595, 1,524, 1,467, 1,080, 980,
897, 820 cm-1
.
Results and discussion
To search for the optimal conditions, the synthesis of compound 3b was selected as
a model reaction. The reaction was carried out by heating a mixture of 3-methyl-1H-
123

Synthesis of 4,40-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols)
pyrazol-5(4H)-one 1 (2 mmol), and 4-cholorobenzaldehyde 2b (1 mmol) in the
absence or presence of H3PW12O40 as catalyst in different solvents, including H2O,
EtOH, CH3CN, CHCl3, CH2Cl2, n-hexane and also under solvent-free conditions.
The results are summarized in Table 1. Without the catalyst, no or a trace product
was obtained at reflux temperature in solvent or 120 °C under solvent-free
conditions even after reaction for 120 min (entries 1–7). Ethanol proved to be a
much better solvent in terms of yield as well as reaction time than all the others.
Although, there are no significant differences in yields between EtOH and H2O, the
reactions in EtOH have much shorter reaction times. The excellent yield of the
product was obtained when the reaction was conducted in refluxing EtOH in the
presence of 10 mol % of the H3PW12O40 catalyst (entry 18). No significant
Table 1 Optimization of reaction conditions for the synthesis of compound 3b catalyzed by H3PW12O40
Entry
Catalyst
Mol %
Solvent
T (°C)
Time (min)
Isolated yield (%)
1
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H3PW12O40
H4SiW12O40
H4SiW12O40
H4SiW12O40
H4SiW12O40
H4SiW12O40
H4SiW12O40
H4SiW12O40
H4SiW12O40
–
H2O
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
120
120
120
120
120
120
120
120
120
30
–
2
–
EtOH
CH3CN
CHCl3
CH2Cl2
n-hexane
–
–
3
–
–
4
–
–
5
–
–
6
–
–
7
–
–
8
5
H2O
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
120
60
65
20
Trace
Trace
Trace
20
81
85
94
98
97
43
44
17
58
60
72
74
74
9
5
EtOH
CH3CN
CHCl3
CH2Cl2
n-hexane
–
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
5
120
120
120
120
120
90
5
5
5
5
7
H2O
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
7
EtOH
H2O
20
10
10
15
5
90
EtOH
EtOH
H2O
15
15
120
30
5
EtOH
CH3CN
H2O
5
120
90
7
7
EtOH
H2O
20
10
10
15
90
EtOH
EtOH
15
15
Reaction conditions: 3-methyl-1H-pyrazol-5(4H)-one 1 (2 mmol), and 4-cholorobenzaldehyde 2b
(1 mmol)
123

A. Vafaee et al.
improvement in the time of the reaction was observed using higher amount of the
catalyst (entry 19). For comparison and to show the merit of the H3PW12O40
catalyst, synthesis of the model compound, 3b, was also investigated using another
HPA, silicotungstic acid (H4SiW12O40) as catalyst. The results are shown in Table 1
(entries 20–27). As depicted, H3PW12O40 proved to be the better catalyst than
H4SiW12O40 in terms of reaction time and yield. Therefore, our optimized condition
is 10 mol % of H3PW12O40 in refluxing EtOH. All subsequent reactions were
carried out in these optimized conditions.
Using these optimized reaction conditions, the scope and efficiency of this
approach was explored for the synthesis of a wide variety of 4,40-(arylmethyl-
ene)bis(3-methyl-1H-pyrazol-5-ols) and the obtained results are summarized in
Table 2. All the aforementioned reactions (Table 2) delivered excellent product
yields and accommodated a wide range of aromatic aldehydes bearing both
electron-donating and electron-withdrawing substituents. Also, heteroaromatic
aldehydes performed well and produced a high yield of the corresponding product.
Although there are only two papers on the synthesis of 4,40-(arylmethylene)bis(1-
unsubstituted-1H-pyrazol-5-ols) [22, 23], to further evaluate the overall utility of the
current methodology, we compared our results with those of the other methods
reported for the synthesis of 4,40-(arylmethylene)bis(1-substituted-1H-pyrazol-5-
ols). This comparison is shown in Table 3. It is clear from the data that our method
has short reaction times and provides higher yields of the products.
We also used our optimized reaction conditions to evaluate the reusability of the
catalyst H3PW12O40. After completion of the reaction, the reaction mixture was
cooled to room temperature, the product was collected by filtration, and washed
repeatedly with cold water. The combined filtrate was evaporated to dryness under
reduced pressure. The solid catalyst was collected, dried at 70 °C under vacuum for
1 h, and reused for the same experiment. We found that the catalyst could be used at
least ten times with only a slight reduction in activity (Fig. 1).
Furthermore, retention of the structure of the catalyst was confirmed by
comparing the FT-IR spectra of the recovered catalysts (Fig. 2b–f) with that of the
fresh catalyst (Fig. 2a) for the model reaction. As shown, these spectra are almost
identical.
Considering the Brønsted acidic nature of H3PW12O40:HA, a possible
mechanism is proposed as depicted in Scheme 2. The catalyst plays a significant
role in increasing the electrophilic character of the electrophiles in the reaction. The
reaction occurs via initial formation of the intermediate [I], prepared by
Knoevenagel condensation of first equivalent of enolic form of 3-methyl-1H-
pyrazol-5(4H)-one 1 and aryl aldehydes 2a–2j, which reacts subsequently with
second equivalent of enolic form of 1 to afford the desired products 3a–3j. Under
these conditions, attempts to isolate the intermediate [I] failed even after careful
monitoring of the reactions.
In summary, we successfully developed a simple, efficient and ecofriendly
method for the synthesis of 4,40-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols) by
one-pot reaction of two equivalents of 3-methyl-1H-pyrazol-5(4H)-one with aryl
aldehydes, using cheap and readily available H3PW12O40 as homogeneous catalyst.
Some attractive features of this protocol are excellent yields, simple procedure,
123

Synthesis of 4,40-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols)
Table 2 H3PW12O40 catalyzed synthesis of 4,40-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols) 3a–3j
Entry Ar
Product*
Time
(min)
Isolated yield m.p. (8C)
(%)
Found
Reported
1
15
91
242–244 230–232 [23]
3a
2
15
98
220–222 224–226 [23]
3b
3c
3
10
92
269–270 271–272 [23]
4
10
93
297–299 300–302 [23]
3d
3e
5
60
94
261–263 262–264 [23]
123

A. Vafaee et al.
Table 2 continued
Entry Ar
Product*
Time
(min)
Isolated yield m.p. (8C)
(%)
Found
Reported
–
6
10
97
218–222
3f
7
60
96
191–193
–
3g
3h
8
60
93
189–191
–
9
60
97
211–212
–
3i
3j
10
60
93
203–205
–
Reaction conditions: 3-Methyl-1H-pyrazol-5(4H)-one 1 (2 mmol), aryl aldehyde 2a–2j (1 mmol),
H3PW12O40 (10 mol % based on aryl aldehyde), EtOH (2 ml), reflux
* Characterization of new products were performed according to their IR, 1H NMR, and 13C NMR data,
and for known products by their IR spectral data and a comparison of their melting points with those of
authentic samples
123

Synthesis of 4,40-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols)
Table 3 Comparison of the efficiencies of different catalysts for the synthesis of 4,40-(arylmethyl-
ene)bis(1-(un)substituted-1H-pyrazol-5-ols)
Catalyst
Conditions
Time
(min)
Yield References
(%)
Solvent T/°C
Other
Silica-bonded ionic liquid
EtOH
–
Reflux
–
–
60–270 77–90 [20]
Silica-bonded N-propylpiperazine
sulfamic acid
80
35–60
80–93 [21]
2-Hydroxy ethylammonium
propionate
–
90
–
10–80
77–96 [22]
Sodium dodecyl sulfate
H2O
Reflux
Reflux
–
–
60–240 78–92 [23]
130–260 74–90 [24]
Sulfuric acid ([3-(3-silicapropyl)
sulfanyl]propyl)ester
EtOH
Poly(ethylene glycol)-bound
sulfonic acid
H2O
Reflux
r.t.
–
30–120 76–94 [25]
[HMIM]HSO4
EtOH
Ultrasonic
irradiation
30–75
40–92 [26]
Phosphomolybdic acid
LiOH.H2O
EtOH
H2O
Reflux
90
–
–
–
210–330 91–96 [27]
60–75 79–86 [28]
Cellulose sulfuric acid
EtOH/
H2O
Reflux
10–200 74–97 [29]
Silica-bonded N-
propyltriethylenetetramine
EtOH
Reflux
–
15–120 72–93 [30]
Silica-bonded S-sulfonic acid
Pyridine trifluoroacetate
H3PW12O40
EtOH
H2O
Reflux
70
–
–
–
40–240 75–90 [31]
300–900 75–95 [32]
EtOH
Reflux
10–60
93–98 this work
Fig. 1 Effect of recycling on catalytic performance of H3PW12O40 in the synthesis of 3b in model
reaction
123

A. Vafaee et al.
Fig. 2 FT-IR spectra of fresh catalyst H3PW12O40 (run 1, a), and recovered catalysts (runs 2, 4, 6, 8 and
10, b–f, respectively) for synthesis of compound 3b in model reaction
Scheme 2 Plausible mechanism for the formation of 4,40-(arylmethylene)bis(3-methyl-1H-pyrazol-5-
ols) in the presence of H3PW12O40:HA as catalyst
123

Synthesis of 4,40-(arylmethylene)bis(3-methyl-1H-pyrazol-5-ols)
short reaction times, easy work-up, high catalytic activity and recyclability, and
reusability of the catalyst. The catalyst can be used at least ten times without
substantial reduction in its catalytic activity.
Acknowledgments The authors express their gratitude to the Islamic Azad University, Mashhad
Branch for its financial support.
References
1. N. Uramaru, H. Shigematsu, A. Toda, R. Eyanagi, S. Kitamura, S. Ohta, J. Med. Chem. 53, 8727
(2010)
2. D.M. Bailey, P.E. Hansen, A.G. Hlavac, E.R. Baizman, J. Pearl, A.F. Defelice, M.E. Feigenson, J.
Med. Chem. 28, 256 (1985)
3. K. Sujatha, G. Shanthi, N.P. Selvam, S. Manoharan, P.T. Perumal, M. Rajendran, Bioorg. Med.
Chem. Lett. 19, 4501 (2009)
4. D. Singh, D. Singh, J. Indian Chem. Soc. 68, 165 (1991)
5. J.J. Liu, M.Y. Zhao, X. Zhang, X. Zhao, H.L. Zhu, Mini Rev. Med. Chem. 13, 1957 (2013)
6. S. Sugiura, S. Ohno, O. Ohtani, K. Izumi, T. Kitamikado, H. Asai, K. Kato, M. Hori, H. Fujimura, J.
Med. Chem. 20, 80 (1977)
7. Y. Liu, G. He, C. Kai, Y. Li, H. Zhu, J. Heterocycl. Chem. 49, 1370 (2012)
8. M. Londershausen, Pestic. Sci. 48, 269 (1996)
9. R.C. Maurya, R. Verma, Indian J. Chem. Sect. A 36, 596 (1997)
10. A.D. Garnovskii, A.I. Uraev, V.I. Minkin, Arkivoc 3, 29 (2004)
11. H. Nakagawa, R. Ohyama, A. Kimata, T. Suzuki, N. Miyata, Bioorg. Med. Chem. Lett. 16, 5939
(2006)
12. P. Kessler, T. Aybek, G. Neidhart, S. Dogan, D.H. Bremerich, V. Lischke, C. Byhahan, J. Cardio-
thorac. Vasc. Anesth. 19, 32 (2005)
13. M.Z. Wisniewski, W.J. Surga, E.M. Opozda, Transit. Met. Chem. 19, 353 (1994)
14. M. F. El-Shehry, E. M. El-Telbani, R. H. Swellem, J. Chem. Res. 33, 625 (2009)
15. W.S. Hamama, Synth. Commun. 31, 1335 (2001)
16. M. Bortoluzzi, G. Paolucci, B. Pitteri, A. Vavasori, V. Bertolasi, Organometallics 28, 3247 (2009)
17. X.L. Li, Y.M. Wang, B. Tian, T. Matsuura, J.B. Meng, J. Heterocycl. Chem. 35, 129 (1998)
18. Z. Karimi-Jaberi, B. Pooladian, M. Moradi, E. Ghasemi, Chin. J. Catal. 33, 1945 (2012)
19. S. Sobhani, A.R. Hasaninejad, M. Faal, Z. Maleki, P. Parizi, Synth. Commun. 42, 2245 (2012)
20. M. Baghernejad, K. Niknam, Int. J. Chem. 4, 52 (2012)
21. S. Tayebi, K. Niknam, Iranian. J. Catal. 2, 69 (2012)
22. Z. Zhou, Y. Zhang, Green Chem. Lett. Rev. 7, 18 (2014)
23. W. Wang, S.X. Wang, X.Y. Qin, J.T. Li, Synth. Commun. 35, 1263 (2005)
24. S. Tayebi, M. Baghernejad, D. Saberi, K. Niknam, Chin. J. Catal. 32, 1477 (2011)
25. A. Hasaninejad, M. Shekouhy, A. Zare, S.M.S. Hoseini Ghattali, N. Golzar, J. Iran Chem. Soc. 8, 411
(2011)
26. H. Zang, Q. Su, Y. Mo, B. Cheng, Ultrason. Sonochem. 18, 68 (2011)
27. K.R. Phatangare, V.S. Padalkar, V.D. Gupta, V.S. Patil, P.G. Umape, N. Sekar, Synth. Commun. 42,
1349 (2012)
28. M.A. Gouda, A.A. Abu-Hashem, Green Lett. Rev. 5, 203 (2012)
29. E. Mosaddegh, A. Hassankhani, A. Baghizadeh, J. Chil. Chem. Soc. 55, 419 (2010)
30. K. Niknam, M. Sadeghi Habibabad, A. Deris, N. Aeinjamshid, Monatsh Chem. 144, 987 (2013)
31. K. Niknam, D. Saberi, M. Sadegheyan, A. Deris, Tetrahedron Lett. 51, 692 (2010)
32. E. Soleimani, S. Ghorbani, M. Taran, A. Sarvary, CR Chimie 15, 955 (2012)
33. D. Singh, D. Singh, J. Chem. Eng. Data 29, 355 (1984)
34. A. Hasaninejad, A. Zare, M. Shekouhy, N. Golzar, Org. Prep. Proced. Int. 43, 131 (2011)
35. N.P. Tale, G.B. Tiwari, N.N. Karade, Chin. Chem. Lett. 22, 1415 (2011)
36. M.N. Elinson, A.S. Dorofeev, R.F. Nasybullin, G.I. Nikishin, Synthesis 12, 1933 (2008)
37. T. Okuhara, N. Mizuno, M. Misono, Adv. Catal. 41, 113 (1996)
38. A. Davoodnia, M. Bakavoli, Gh Barakouhi, N. Tavakoli-Hoseini, Chin. Chem. Lett. 18, 1483 (2007)
123

A. Vafaee et al.
39. I.V. Kozhevnikov, Chem. Rev. 98, 171 (1998)
40. I.V. Kozhevnikov, Catal. Rev. Sci. Eng. 37, 311 (1995)
41. A. Emrani, A. Davoodnia, N. Tavakoli-Hoseini, Bull. Korean Chem. Soc. 32, 2385 (2011)
42. A. Khojastehnezhad, A. Davoodnia, M. Bakavoli, N. Tavakoli-Hoseini, M. Zeinali-Dastmalbaf,
Chin. J. Chem. 29, 297 (2011)
43. A. Davoodnia, A. Zare-Bidaki, H. Behmadi. Chin. J. Catal. 33, 1797 (2012)
44. F. Taghavi-Khorasani, A. Davoodnia, Res. Chem. Intermed. (2013). doi:10.1007/s11164-013-1356-0
45. M.M. Mojtahedi, M.R. Jalali, M.S. Abaee, M. Bolourtchian, Heterocycl. Commun. 12, 225 (2006)
123