Cu–S-(propyl)-2-aminobenzothioate on magnetic nanoparticles: highly efficient and reusable catalyst for synthesis of polyhydroquinoline derivatives and oxidation of sulfides

Article abstract of DOI:10.1002/aoc.3478

Cu–S-(propyl)-2-aminobenzothioate supported on functionalized Fe₃O₄ magnetic nanoparticles is reported as a reusable and highly efficient nanocatalyst for the one-pot synthesis of polyhydroquinoline derivatives and also for selective

Full text of DOI:10.1002/aoc.3478

Full paper
Received: 1 February 2016
Revised: 25 February 2016
Accepted: 26 February 2016
Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI 10.1002/aoc.3478
Cu–S-(propyl)-2-aminobenzothioate on
magnetic nanoparticles: highly efficient and
reusable catalyst for synthesis of
polyhydroquinoline derivatives and oxidation
of sulfides
Arash Ghorbani-Choghamarani*, Bahman Tahmasbi, Parisa Moradi
and Nasrin Havasi
Cu–S-(propyl)-2-aminobenzothioate supported on functionalized Fe3O4 magnetic nanoparticles is reported as a reusable and
highly efficient nanocatalyst for the one-pot synthesis of polyhydroquinoline derivatives and also for selective oxidation of
sulfides to sulfoxides. The prepared nanoparticles were characterized using Fourier transform infrared spectroscopy, vibrating
sample magnetometry, thermogravimetric analysis, transmission and scanning electron microscopies, energy-dispersive X-ray
spectroscopy, X-ray diffraction, inductively coupled plasma atomic emission spectroscopy and atomic absorption spectroscopy.
The nanocatalyst was easily recovered using an external magnet and reused several times without significant loss of its catalytic
efficiency. Copyright © 2016 John Wiley & Sons, Ltd.
Keywords: magnetic nanoparticles; polyhydroquinoline; sulfoxides; organometallic catalyst
biologically active sulfoxides play an important role as therapeutic
agents such as antibacterial, antifungal, antihypertensive, anti-ulcer
Introduction
In recent years, catalysts supported on nanoparticles have attracted
much attention in organic reactions.[1] The main drawback of these
catalysts is their separation; because nanoparticles have diameters
of less than 100 nm, they cannot be separated using conventional
methods such as filtration techniques.[2] This drawback can be over-
come using magnetic nanoparticles (MNPs), which can be easily re-
covered from a reaction mixture with an external magnet.[3]
Furthermore, magnetic separation of MNPs is more effective and
easier than filtration or centrifugation.[4] MNPs are readily available
and have high surface area resulting in high catalyst loading capac-
ity and outstanding stability.[5] Functionalized MNPs are kinds of
novel functional materials, which have been widely used in biotech-
nology and catalysis studies.[6] The presence of many hydroxyl
groups on the surface of MNPs leads to reaction with alkoxysilane
reagents and formation of Si–O bonds which support terminal func-
tional groups available for immobilization of other substances.[7]
Herein, we report a new complex of copper that is immobilized on
Fe3O4 MNPs and further used as an excellent nano-organometallic
catalyst for the one-pot synthesis of polyhydroquinoline derivatives;
these derivatives have been reported to possess a wide range of
pharmaceutical activities and biological properties such as
hepatoprotective, vasodilator, antitumor, antiatherosclerotic,
geroprotective, bronchodilator and antidiabetic activities and also
to have the ability to modulate calcium channels.[8–12]
and anti-atherosclerotic agents as well as psychotropics and
vasodilators.[15–17] For this reason, many methods involving various
catalysts and oxidants have been reported for this organic oxida-
tion. Concerning the use of a green oxidant, H2O2 (with only water
as a by-product) has received attention because of its environmen-
tal implications, high atom efficiency, ready availability and lower
cost compared to other oxidizing agents.[18–21]
Experimental
Preparation of Cu–S-(propyl)-2-aminobenzothioate supported
on functionalized Fe3O4 MNPs (Cu-SPATB/Fe3O4)
Free Fe3O4 MNPs were synthesized according to our recently
reported procedure via a chemical co-precipitation technique using
Fe3+ and Fe2+ in basic solution at 80 °C.[4] The obtained Fe3O4
nanoparticles (1.5g) were dispersed in 50 ml of toluene using son-
ication for 30min, and then (3-mercaptopropyl)trimethoxysilane
(MPTMS; 2.5 ml) was added to this mixture. The reaction mixture
*
Correspondence to: A. Ghorbani-Choghamarani, Department of Chemistry, Ilam
University, PO Box 69315516, Ilam, Iran. E-mail: arashghch58@yahoo.com or a.
ghorbani@mail.ilam.ac.ir
Also, the oxidation of sulfides into sulfoxides is useful for various
biological, medical and nanotechnological applications.[13,14] Some
Department of Chemistry, Faculty of Science, Ilam University, PO Box69315516,
Ilam, Iran
Appl. Organometal. Chem. (2016)
Copyright © 2016 John Wiley & Sons, Ltd.

A. Ghorbani-Choghamarani, B. Tahmasbi, P. Moradi and N. Havasi
was stirred under nitrogen atmosphere at 40 °C for 8 h. Then, the
MNPs were washed with ethanol five times and separated through
magnetic decantation. The functionalized nanoparticles (MPTMS-
MNPs) were dried at room temperature. The obtained MPTMS-
MNPs (1g) were dispersed in 50 ml of ethanol using sonication for
20 min, and then isatoic anhydride (2.5mmol) was added to the re-
action mixture. The reaction mixture was stirred under nitrogen at-
mosphere at 80 °C for 8 h. Then, the resulting nanoparticles (ATBA-
MNPs) were washed with ethanol several times, separated using
magnetic decantation and dried at room temperature. The ob-
tained ATBA-MNPs (0.5g) were dispersed in 25 ml of ethanol using
sonication for 20min, and then Cu(NO3)2Á9H2O (0.5mmol) was
added to the reaction mixture. The reaction mixture was stirred un-
der nitrogen atmosphere at 80 °C for 20 h. The final product was
separated using magnetic decantation and washed with ethanol
to remove the unattached substrates. The nanoparticle product
(Cu-SPATB/Fe3O4) was dried at room temperature.
Scheme 1. Synthesis of Cu-SPATB/Fe3O4 .
Catalyst characterization
The size of the catalyst particles was evaluated using SEM and TEM.
The SEM and TEM images of Cu-SPATB/Fe3O4 show that the catalyst
is formed of nanometre-sized particles (Fig. 1).
To characterize the catalyst in terms of the copper metal
supporting on the Fe3O4 surface, EDS analysis of Cu-SPATB/Fe3O4
was conducted. As depicted in Fig. 2, the EDS spectrum of
Cu-SPATB/Fe3O4 shows the presence of Fe, O, Si, C, S and N and
as well as Cu species in the catalyst.
General procedure for synthesis of polyhydroquinoline
derivatives
A
mixture of aldehyde (1mmol), dimedon (1mmol),
ethylacetoacetate (1mmol), ammonium acetate (1.2mmol) and
Cu-SPATB/Fe3O4 (0.02 g) was stirred in PEG-400 at 80°C with the
progress of the reaction being monitored using TLC. After comple-
tion of the reaction, the catalyst was separated using an external
magnet and washed with ethyl acetate. Then, the solvent was evap-
orated and all products were recrystallized from ethanol. The pure
polyhydroquinoline derivatives were obtained in good to excellent
yields.
General procedure for oxidation of sulfides to sulfoxides
Cu-SPATB/Fe3O4 (0.005g) was added to a solution of sulfide
(1mmol) and 33% H2O2 (0.4ml), and the mixture was stirred under
solvent-free conditions at room temperature for the specified time
with the progress of the reaction being monitored using TLC. After
completion of the reaction, the catalyst was separated using an
external magnet. The product was extracted with CH2Cl2, washed
with water (5ml) and dried under vacuum at room temperature.
Results and discussion
Catalyst preparation
The catalyst was prepared using a concise route, which is outlined
in Scheme 1. Initially, MPTMS-MNPs were prepared according to a
reported procedure.[4] Subsequently, 2-aminothiobenzamide
supported on Fe3O4 (SPATB-MNP) was synthesized by reaction of
MPTMS-MNPs with isatoic anhydride. Ultimately, Cu-SPATB/Fe3O4
was obtained via coordination of copper with 2-
aminothiobenzamide immobilized on Fe3O4 (Scheme 1). This cata-
lyst was characterized using transmission electron microscopy
(TEM), scanning electron microscopy (SEM), energy-dispersive
X-ray spectroscopy (EDS), atomic absorption spectroscopy (AAS), in-
ductively coupled plasma atomic emission spectroscopy (ICP-OES),
X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectros-
copy, vibrating sample magnetometry (VSM) and thermogravimet-
ric analysis (TGA).
Figure 1. (a) SEM image and (b) TEM image of Cu-SPATB/Fe3O4.
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Appl. Organometal. Chem. (2016)

Cu-SPATB/Fe3O4 applied as organometallic catalyst in organic reactions
of weight loss below 200 °C corresponds to the removal of the
physically and chemically adsorbed solvents or surface hydroxyl
groups, and the other weight loss appearing in the range
200–700 °C is mainly related to the decomposition of organic
fragments and organic ligands on Fe3O4 MNPs.
The thermal stability of the magnetic catalyst was also deter-
mined, since the synthesis of many organic compounds is carried
out at high temperature. As shown in Fig. 3, the Cu-SPATB/Fe3O4
catalyst is stable even at 220°C.
Successful functionalization of the Fe3O4 MNPs can be inferred
using FT-IR spectroscopy. Figure 4 shows FT-IR spectra of Fe3O4
MNPs, MPTMS-MNPs, SPATB-MNPs and Cu-SPATB/Fe3O4. The
Fe–O stretching vibration is observed in terms of two strong
absorption bands near 580 and 440 cmÀ1; also symmetric and
asymmetric modes of the O–H bond stretching vibration near
3430 cmÀ1 and O–H deformation vibration near 1630 cmÀ1 are
observed in the FT-IR spectrum of bare Fe3O4 MNPs.[4,5] Immobiliza-
tion of MPTMS on the surface of Fe3O4 MNPs is proved with the
appearance of two peaks at 2922 and 2852 cmÀ1 corresponding
to the C–H stretching vibrations, and also S–H stretching vibration
mode as a weak band that appears at 2450 cmÀ1 (Fig. 4(b)) which
is absent in the FT-IR spectra of Fe3O4 MNPs, SPATB-MNPs and
Cu-SPATB/Fe3O4 (Figs 4(a), (c) and (d)). Reaction of isatoic anhydride
with SH grafted on Fe3O4 MNPs produces SPATB-MNPs in which the
Figure 2. EDS spectrum of Cu-SPATB/Fe3O4.
In order to determine the exact amount of Cu in Cu-SPATB/
Fe3O4, the AAS technique was used. From this analysis, the amount
of Cu in the catalyst is found to be 0.25 × 10À3 mol gÀ1 based on
AAS. This is confirmed from the results of ICP-OES, from which the
amount of Cu in the catalyst is found to be 25.64× 10À5 mol gÀ1
based on ICP-OES.
TGA was used to determine the percent of organic functional
groups chemisorbed onto the surface of Fe3O4. Figure 3 shows
the TGA curves for bare Fe3O4 MNPs, MPTMS-MNPs, SPATB-MNPs
and the catalyst. The TGA curve of Cu-SPATB/Fe3O4 shows the mass
loss of organic functional groups as it decomposes upon heating.
The weight loss at temperatures below 200 °C is due to the removal
of physically adsorbed solvent and surface hydroxyl groups.[5]
Organic groups have been reported to desorb at temperatures
above 260 °C. In the TGA curve of the catalyst, a weight loss of
about 10% from 260 to 600 °C is the result of decomposition of
the organic layer and Cu complex grafted to the Fe3O4 surface.
Meanwhile, weight losses of about 2, 5 and 9% from 260 to
600 °C occur for Fe3O4 MNPs, MPTMS-MNPs and SPATB-MNPs,
respectively. By comparison of the mass losses for organic moieties
of different stages of catalyst preparation, the good grafting of the
Cu complex on Fe3O4 MNPs is verified. For all samples, the first step
Figure 3. TGA curves of Fe3O4 MNPs (black curve), MPTMS-MNPs (blue
Figure 4. FT-IR spectra of (a) Fe3O4 MNPs, (b) MPTMS-MNPs, (c) SPATB-
curve), SPATB-MNPs (pink curve) and Cu-SPATB/Fe3O4 (green curve).
MNPs and (d) Cu-SPATB/Fe3O4.
Appl. Organometal. Chem. (2016)
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A. Ghorbani-Choghamarani, B. Tahmasbi, P. Moradi and N. Havasi
presence of carbonyl group is indicated by the 1630–1640 cmÀ1
band in its FT-IR spectrum (Fig. 4(c)). In addition, in the spectrum
of Cu-SPATB/Fe3O4, the broad band in the range 1400–1650 cmÀ1
is attributed to the formation of Cu complex.
The superparamagnetic property of the particles was measured
using the VSM technique. The magnetization curves of Fe3O4 MNPs
and Cu-SPATB/Fe3O4 are shown in Fig. 5. The decrease in the mag-
netization of the catalyst compared with the Fe3O4 MNPs indicates
the successful functionalization of the Fe3O4 MNPs by organic
layers and Cu complex.[22]
The XRD pattern of Cu-SPATB/Fe3O4 is shown in Fig. 6. The
XRD pattern of the catalyst shows peaks at 2θ values of 30.2°,
35.8°, 43.4°, 54.0°, 57.3° and 63.0° related to crystal planes in
the Fe3O4 cubic lattice, which are in agreement with Fe3O4
standard data.[4]
Scheme 2. Cu-SPATB/Fe3O4-catalysed synthesis of polyhydroquinoline
derivatives.
The reaction of a variety of aldehydes with dimedon,
ethylacetoacetate and ammonium acetate was then investi-
gated to confirm the generality of the present method.
The polyhydroquinoline derivatives are obtained in high
yields. The results of this study are summarized in Table 2.
A variety of benzaldehydes bearing electron-donating sub-
stituents (Table 2, entries 2–6) and electron-withdrawing sub-
stituents (Table 2, entries 7–9) were successfully employed to
prepare the corresponding polyhydroquinoline derivatives in
excellent yields.
Catalytic study
As a part of our ongoing programme directed towards the develop-
ment of new methods, we tested the catalytic activity of Cu-SPATB/
Fe3O4 for the synthesis of polyhydroquinoline derivatives
(Scheme 2).
In the second part of our study of the catalytic activity of Cu-
SPATB/Fe3O4 in organic synthesis, we investigated the applicability
In order to optimize reaction conditions, we selected 4-
chlorobenzaldehyde as a model compound in various solvents
and in the presence of different amounts of catalyst at 60–80 °C
As evident from Table 1, 0.02 g of Cu-SPATB/Fe3O4 in PEG-400 at
80 °C are the ideal reaction conditions for the synthesis of
polyhydroquinoline derivatives.
Table 1. Optimization of conditions for synthesis of
polyhydroquinolines using the condensation of 4-chlorobenzaldehyde,
dimedon, ethylacetoacetate and ammonium acetate as a model reac-
tion in PEG-400
Entry Solvent Catalyst (mg)Temperature (°C)Time (min)Yield (%)a
1
2
3
4
5
6
PEG-400
PEG-400
Ethyl acetate
Ethanol
20
15
20
20
20
20
80
80
80
80
80
60
65
65
65
65
65
65
98
61
56
80
43
53
Water
PEG-400
aIsolated yields.
Figure 5. Magnetization curves for (a) Fe3O4 MNPs and (b) Cu-SPATB/Fe3O4.
Table 2. Synthesis of polyhydroquinolines catalysed by Cu-SPATB/
Fe3O4 in PEG-400 and at 80 °C
Entry
Aldehyde
Time Yield
(min)
M.p.
(°C)
(%)a
1
2
3
4
5
6
7
8
9
10
Benzaldehyde
150
85
89
98
94
92
88
91
92
89
98
90
217–219[23]
175–177[5]
231–234[9]
249–250[5]
202–204[23]
252–255[23]
250–252[9]
179–181[9]
238–39[23]
245–247
4-Ethoxybenzaldehyde
4-Hydroxybenzaldehyde
4-Methoxybenzaldehyde
3,4-Dimethoxybenzaldehyde
4-Methylbenzaldehyde
4-Bromobenzaldehyde
4-Fluorobenzaldehyde
4-Chlorobenzaldehyde
Terephthalaldehyde
85
210
180
240
120
150
65
80
aIsolated yield.
Figure 6. XRD pattern of Cu-SPATB/Fe3O4.
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Cu-SPATB/Fe3O4 applied as organometallic catalyst in organic reactions
of the catalyst to the selective oxidation of sulfides to sulfoxides.
The reactions occur with short reaction times giving good to excel-
lent yields under solvent-free condition at room temperature
(Scheme 3).
results reveal that this methodology is effective for a wide range
of sulfides.
Based on previous literature, a plausible reaction mechanism for
the selective oxidation of sulfides in the presence of organometallic
catalysts containing Cu(II) metal ions[24–26] is shown in Scheme 6.
Reaction of H2O2 with Cu catalyst leads to intermediate A, which
is converted to active oxidant B. In the next step, nucleophilic attack
For optimization of the reaction conditions, we examined the
oxidation of methylphenyl sulfide using hydrogen peroxide
(0.4 ml) as a model reaction in the presence of various amounts
of Cu-SPATB/Fe3O4 (Table 3, entries 1–4). The experiments show
that the oxidation reaction does not occur in the absence of the
catalyst (Table 3, entry 1). Also we examined the model reaction
in various solvents such as ethyl acetate, water, acetonitrile and
ethanol as well as under solvent-free condition (Table 3, entries
4–8). The best results are obtained using 0.005 g of Cu-SPATB/
Fe3O4 at room temperature under solvent-free conditions
(Table 3, entry 3).
Using the optimum conditions determined, various sulfides were
converted to their corresponding sulfoxides in the presence of Cu-
SPATB/Fe3O4 as catalyst at room temperature. The all products are
obtained in high to excellent yields. The results of this study are
summarized in Table 4.
Table 4. Oxidation of sulfides to sulfoxides using H2O2 in the presence
of Cu-SPATB/Fe3O4 at room temperature under solvent-free conditions
Entry
Sulfide
Time (min) Yield (%)a
1
2
3
4
5
6
7
Methylphenyl sulfide
Tetrahydrothiophene
2-Methylthioethanol
2-Phenylthioethanol
Methyl 3-(methylthio)propanoate
Ethylphenyl sulfide
130
5
96
94
92
91
93
91
97
10
10
15
190
135
4-Chlorothioanisole
Because of the mild conditions of the described heterogeneous
system, any over-oxidation to sulfones during the oxidation of
sulfides is not observed (Scheme 4).
aIsolated yields.
This oxidizing system allows the chemoselective oxidation of
2-(phenylthio)ethanol and 2-(methylthio)ethanol to the corre-
sponding sulfoxides (Table 4, entries 3 and 4). Interestingly, primary
hydroxyl groups in these substrates remain intact during the oxida-
tion reactions (Scheme 5). This result indicates that the present pro-
tocol could be applicable to the chemoselective oxidation of
sulfides in the presence of other functional groups. Therefore, the
Scheme 4. Chemoselective oxidation of sulfides in the presence Cu-
SPATB/Fe3O4 using H2O2 without over-oxidation.
Scheme 3. Cu-SPATB/Fe3O4-catalysed oxidation of sulfides to sulfoxides.
Scheme 5. Chemoselective oxidation of sulfides in the presence of other
functional groups using Cu-SPATB/Fe3O4 as catalyst.
Table 3. Optimization of reaction conditions for oxidation of
methylphenyl sulfide (1 mmol) in the presence of various amounts of
Cu-SPATB/Fe3O4 at room temperature in a variety of solvents using
H2O2 (0.4 ml)
Entry
Solvent
Catalyst (g)
Time (min)
Yield (%)a
1
2
3
4
5
6
7
8
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Ethanol
—
130
130
130
95
Traceb
70
0.003
0.005
0.007
0.005
0.005
0.005
0.005
96
95
60
25
Acetonitrile
Water
60
Trace
Trace
21
60
Ethyl acetate
60
aIsolated yields.
bReaction in the absence of catalyst.
Scheme 6. Proposed mechanism for oxidation of sulfides in the presence
of Cu-SPATB/Fe3O4 using H2O2.
Appl. Organometal. Chem. (2016)
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A. Ghorbani-Choghamarani, B. Tahmasbi, P. Moradi and N. Havasi
of the sulfide on this intermediate gives cation C, which produces
the corresponding sulfoxide.
To extend the scope of our work, the catalytic activity of
Cu-SPATB/Fe3O4 has been examined for other condensation reaction
systems such as synthesis of 1,4-dihydropyridines, dihydropyrano
[2,3-c]pyrazoles, dihydropyrano[3,2-c]chromen-2-ones, 5-substituted
1H-tetrazoles, benzoimidazoles and benzothiazoles. The models of
these condensations in the presence of Cu-SPATB/Fe3O4 are sum-
marized in Scheme 7. Therefore, Cu-SPATB/Fe3O4 is an efficient
and powerful catalyst for a wide range of multicomponent
condensations.
Figure 7. Recycling of Cu-SPATB/Fe3O4 in the oxidation of
tetrahydrothiophene.
Reusability of catalyst
The reusability of catalysts is one of their most important advan-
tages, which makes them useful for commercial applications. We
have found that Cu-SPATB/Fe3O4 can be rapidly recovered and
demonstrates excellent recyclability. In order to investigate this
issue, the recyclability of the catalyst was examined in the oxida-
tion of tetrahydrothiophene. After the completion of the reaction,
the catalyst was separated using an external magnet. The remain-
ing catalyst was washed with ethyl acetate to remove residual
product, the catalyst was dried and fresh substrate was added
to the recovered catalyst without any activation and employed
for the next reaction. As shown in Fig. 7, the catalyst can be
recycled for up to five runs without any significant loss of cata-
lytic activity. The average isolated yield for five successive runs
is 92.6%, which clearly demonstrates the practical recyclability
of this catalyst. In addition, one of the attractive features of this
catalyst is the rapid and efficient separation of the catalyst using
an appropriate external magnet, which minimizes the loss of
catalyst during separation.
In order to investigate the leaching of the catalyst, the amount of
Cu in the catalyst was determined using ICP-OES after being
recycled five times. The amount of Cu in the catalyst is found to
be 2.459 × 10À4 mol gÀ1 after five runs based on ICP-OES. Therefore
the catalyst can be recovered and reused without any significant
leaching of Cu metal. Based on the ICP-OES results, the amount of
Cu in the catalyst after being reused five times is comparable to that
in fresh catalyst (2.564 × 10À4 mol gÀ1).
In order to examine the leaching of Cu in reaction mixtures
and the heterogeneity of the described catalyst, we performed
a hot filtration test for the synthesis of ethyl 4-(4-bromophenyl)-
2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate
(Table 2, entry 7). In this experiment we obtained the yield of
product in half the time of the reaction (60 min), which was
63%. Then the reaction was repeated and in half the time of
the reaction the catalyst was separated and the filtered solution
allowed to react to 120 min; we found the reaction did not pro-
ceed in the second half of the reaction time. The yield of reaction
in this stage was 65%, confirming that the leaching of Cu in the
reaction mixture is negligible.
Comparison of catalyst
In order to describe the catalytic activity of Cu-SPATB/Fe3O4, we
compared the results for the oxidation of methylphenyl sulfide
in the presence of this catalyst with those for previously reported
methods (Table 5). This catalyst leads to good reaction time and
higher yield than other catalysts. More importantly, compared
with other catalysts, Cu-SPATB/Fe3O4 is easily prepared using
cheap and commercially available materials, and can be reused
five times without any significant loss of activity. Moreover, meso-
porous silica or some nanoparticles have been used as catalyst
supports, which require high temperature for calcination and
time-consuming and tedious condition to prepare. Also some of
the previously reported catalysts such as heteropolyacids, ionic
liquids or certain polymers are more expensive. The preparation
of nanoboehmite was not air- or moisture-sensitive, and there-
fore this nanomaterial was prepared in water at room tempera-
ture without inert atmosphere. Therefore, this new catalyst is
Scheme 7. Model reactions for the synthesis of 1,4-dihydropyridines,
dihydropyrano[2,3-c]pyrazoles, dihydropyrano[3,2-c]chromen-2-ones, 5-
substituted 1H-tetrazoles and benzoimidazoles in the presence of Cu-
SPATB/Fe3O4.
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Appl. Organometal. Chem. (2016)

Cu-SPATB/Fe3O4 applied as organometallic catalyst in organic reactions
Table 5. Comparison of Cu-SPATB/Fe3O4 for oxidation of methylphenyl sulfide with previously reported procedures
Entry
Substrate
Catalyst
Time (min)
Yield (%)a
Ref.
1
2
3
4
5
6
7
8
9
10
Ph–SCH3
Ph–SCH3
Ph–SCH3
Ph–SCH3
Ph–SCH3
Ph–SCH3
Ph–SCH3
Ph–SCH3
Ph–SCH3
Ph–SCH3
SiO2–W2–Im
150
180
300
150
240
156
120
270
360
95
91.9
90
95
98
88
95
95
93
98
98
27
28
29
30
31
30
32
33
34
Polymer-anchored Cu(II)
VO2F(dmpz)2
Cd–salen–MCM-41
TsOH
Ni–salen–MCM-41
Heterocyclic amine salts of Keggin heteropolyacids
NBS
DSA@MNPs
Cu-SPATB/Fe3O4
This work
aIsolated yields.
[10] M. Saha, A. Kumar Pal, Tetrahedron Lett. 2011, 52, 4872.
[11] M. N. Esfahani, S. J. Hoseini, M. Montazerozohori, R. Mehrabi,
comparable or may be better in terms of price, non-toxicity,
stability and ease of separation.
H. Nasrabadi, J. Mol. Catal. A 2014, 382, 99.
[12] L. Saikia, D. Dutta, D. Kumar Dutta, Catal. Commun. 2012, 19, 1.
[13] A. Ghorbani-Choghamarani, B. Tahmasbi, F. Arghand, S. Faryadi, RSC
Adv. 2015, 5, 92174.
[14] N. Noori, M. Nikoorazm, A. Ghorbani-Choghamarani, J. Porous Mater.
2015, 22, 1607.
[15] A. Shaabani, A. H. Rezayan, Catal. Commun. 2007, 8, 1112.
[16] M. Nikoorazm, A. Ghorbani-Choghamarani, N. Noori, J. Porous Mater.
2015, 22, 877.
Conclusions
In summary, we have reported Cu-SPATB/Fe3O4 as a green, efficient
and reusable nanocatalyst for the oxidation of sulfides to sulfoxides
and for the synthesis of a wide range of polyhydroquinoline deriv-
atives. The advantages of these protocols are the use of commer-
cially available, eco-friendly, cheap and chemically stable
materials, operational simplicity and good to high yields. The prod-
uct separation and catalyst recycling are easy and simple using an
external magnet. The catalyst can be reused five times with little
loss of activity. The catalyst has been characterized using TEM,
SEM, EDS, AAS, ICP-OES, XRD, FT-IR spectroscopy, VSM and TGA.
[17] B. Sreedhar, P. Radhika, B. Neelima, N. Hebalkar, A. K. Mishra, Catal.
Commun. 2008, 10, 39.
[18] M. Hajjami, A. Ghorbani-Choghamarani, R. Ghafouri-Nejad,
B. Tahmasbi, New J. Chem. 2016. DOI:10.1039/C5NJ03546E.
[19] Y. Wang, M. Wang, L. Wang, Y. Wang, X. Wang, L. Sun, Appl.
Organometal. Chem. 2011, 25, 325.
[20] S. Rayati, F. Nejabat, S. Zakavi, Inorg. Chem. Commun. 2014, 40, 82.
[21] M. A. Zolfigol, A. Khazaei, M. Safaiee, M. Mokhlesi, R. Rostamian,
M. Bagheri, M. Shiri, H. G. Kruger, J. Mol. Catal. A 2013, 370, 80.
[22] B. Atashkar, A. Rostami, B. Tahmasbi, Catal. Sci. Technol. 2013, 3, 2140.
[23] A. Ghorbani-Choghamarani, B. Tahmasbi, New J. Copyright © 2016 John
Wiley & Sons, Ltd.Chem. 2016, 40, 1205.
Acknowledgments
This work was supported by the research facilities of Ilam University,
Ilam, Iran.
[24] R. Das, D. Chakraborty, Tetrahedron Lett. 2010, 51, 6255.
[25] A. M. Imelda Jayaseeli, A. Ramdass, S. Rajagopal, Polyhedron 2015, 100, 59.
[26] M. A. Nasseri, B. Zakerinasab, S. Kamayestani, J. Iran. Chem. Soc. 2015,
12, 1457.
[27] S. Thurow, V. A. Pereira, D. M. Martinez, D. Alves, G. Perin, R. G. Jacob,
E. J. Lenardão, Tetrahedron Lett. 2011, 52, 640.
References
[28] S. M. Islam, A. S. Roy, P. Mondal, K. Tuhina, M. Mobarak, J. Mondal,
[1] F. Havasi, A. Ghorbani-Choghamarani, F. Nikpour, New J. Chem. 2015,
39, 6504.
[2] C. W. Lim, I. S. Lee, Nano Today 2010, 412, 5.
[3] S. Laurent, D. Forge, M. Port, A. Roch, C. Robic, L. V. Elst, R. N. Muller,
Chem. Rev. 2008, 108, 2064.
[4] A. Ghorbani-Choghamarani, Z. Darvishnejad, B. Tahmasbi, Inorg. Chim.
Acta 2015, 223, 435.
[5] M. Hajjami, B. Tahmasbi, RSC Adv. 2015, 5, 59194.
[6] G. R. Patzke, Y. Zhou, R. Kontic, F. Conrad, Angew. Chem. Int. Ed. 2011,
826, 50.
Tetrahedron Lett. 2012, 53, 127.
[29] S. Hussain, D. Talukdar, S. K. Bharadwaj, M. K. Chaudhuri, Tetrahedron
Lett. 2012, 53, 6512.
[30] M. Nikoorazm, A. Ghorbani-Choghamarani, H. Mahdavi, S. M. Esmaeili,
Micropor. Mesopor. Mater. 2015, 211, 174.
[31] B. Yu, C. X. Guo, C. L. Zhong, Z. F. Diao, L. N. He, Tetrahedron Lett. 2015,
55, 1818.
[32] A. G. Sathicq, G. P. Romanelli, V. Palermo, P. G. Vazquez, H. J. Thomas,
Tetrahedron Lett. 2008, 49, 1441.
[33] B. Karimi, D. Zareyee, J. Iran. Chem. Soc. 2008, 5, S103.
[34] A. Ghorbani-Choghamarani, H. Rabiei, B. Tahmasbi, B. Ghasemi,
F. Mardi, Res. Chem. Intermed. in press. 2016, DOI:10.1007/s11164-
015-2399-1
[7] M. Z. Kassaee, H. Masrouri, F. Movahedi, Appl. Catal. A 2011, 28, 395.
[8] P. N. Kalaria, S. P. Satasia, D. K. Raval, Eur. J. Med. Chem. 2014, 78, 207.
[9] S. M. Vahdat, F. Chekin, M. Hatami, M. Khavarpour, S. Baghery,
Z. Roshan-Kouhi, Chin. J. Catal. 2013, 34, 758.
Appl. Organometal. Chem. (2016)
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