CoFe2O4@SiO2-CPTES-Guanidine-Cu(II): A novel and reusable nanocatalyst for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones and polyhydroquinolines and oxidation of sulfides

Article abstract of DOI:10.1002/aoc.4636

CoFe₂O₄@SiO₂-CPTES-Guanidine-Cu(II) magnetic nanoparticles were synthesized and used as a new, inexpensive and efficient heterogeneous catalyst for the synthesis of polyhydroquinolines and 2,3-dihydroquinazoline-4(1H)-ones and for the oxidation of sulfides. The structure of this nanocatalyst was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry, thermogravimetric analysis, X-ray diffraction and inductively coupled plasma optical emission spectrometry. Simple preparation, high catalytic activity, simple operation, high yields, use of green solvents, easy magnetic separation and reusability of the catalyst are some of the advantages of this protocol.

Full text of DOI:10.1002/aoc.4636

Received: 12 June 2018
DOI: 10.1002/aoc.4636
Revised: 4 September 2018
Accepted: 4 September 2018
F U L L P A P E R
CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II): A novel and
2
4
2
reusable nanocatalyst for the synthesis of 2,3‐
dihydroquinazolin‐4(1H)‐ones and polyhydroquinolines and
oxidation of sulfides
Leili Heidari | Lotfi Shiri
Department of Chemistry, Faculty of Basic
CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II) magnetic nanoparticles were synthe-
Sciences, Ilam University, PO Box 69315‐
16, Ilam, Iran
2
4
2
5
sized and used as a new, inexpensive and efficient heterogeneous catalyst for
the synthesis of polyhydroquinolines and 2,3‐dihydroquinazoline‐4(1H)‐ones
and for the oxidation of sulfides. The structure of this nanocatalyst was charac-
terized using Fourier transform infrared spectroscopy, scanning electron
microscopy, energy‐dispersive X‐ray spectroscopy, vibrating sample magne-
tometry, thermogravimetric analysis, X‐ray diffraction and inductively coupled
plasma optical emission spectrometry. Simple preparation, high catalytic activ-
ity, simple operation, high yields, use of green solvents, easy magnetic separa-
tion and reusability of the catalyst are some of the advantages of this protocol.
Correspondence
Lotfi Shiri, Department of Chemistry,
Faculty of Basic Sciences, Ilam University,
PO Box 69315‐516, Ilam, Iran.
Email: lshiri47@gmail.com
KEYWORDS
2
2 4
,3‐dihydroquinazoline‐4(1H)‐one, CoFe O , nanocatalyst, polyhydroquinolines, sulfoxide
1
| INTRODUCTION
and they have high thermal and mechanical stability and
[
4–6]
mild saturation magnetization.
Crystallographic
A catalyst is a chemical compound that is capable of
accelerating and guiding the progression of a reaction
that is thermodynamically feasible. Catalysts are divided
into two groups: homogeneous and heterogeneous.
Homogeneous catalysts due to their solubility in reaction
media have advantages such as excellent selectivity and
high catalytic activity. But often separation of these cata-
lysts from reaction mixtures is difficult. Heterogeneous
catalysts have unique properties such as high surface to
volume ratio, thermal, mechanical and chemical stability,
and insolubility in aqueous and organic environments. In
recent years, one of the important applications of nano-
technology has been in the field of catalyst activity and
preparation of nanocatalysts for use as heterogeneous
results for CoFe O show that it has an inverse spinel
2
4
structure. Spinel structures generally have the formula
AB O , where A is a bivalent transition metal such as
2
4
2+
2+
2+
2+
2+
2+
2+
Mg , Fe , Mn , Zn , Cu , Ni and Co and B is
a trivalent transition metal such as Al and Fe .
3+
3+ [7–12]
Heterocyclic compounds, especially those containing
nitrogen, have attracted much attention in modern chem-
istry because these compounds play a key role in the
fields of natural products, medicinal chemistry and mate-
rials chemistry. Polyhydroquinolines, as valuable and
important compounds of N‐heterocycles, because of
pharmacologic applications such as anti‐inflammatory,
antibacterial, antidiabetic and antimalarial drugs and
[13,14]
bronchodilators, have attracted much attention.
[1–3]
catalysts in organic reactions.
Nanocatalysts are
Quinazolines are an important category of nitrogen‐
divided into two types: magnetic and nonmagnetic.
CoFe O nanoparticles are magnetic and black in colour,
containing heterocyclic compounds which consist of
[
15]
fused benzene and pyrimidine rings.
These
2
4
Appl Organometal Chem. 2019;e4636.
wileyonlinelibrary.com/journal/aoc
© 2019 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.4636

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HEIDARI AND SHIRI
compounds have significant biological activity such as
antifungal, antitumour, vasodilatory, anticancer and
on the CoFe O nanoparticles through the reaction of
2
4
CoFe O @SiO ‐CPTES with guanidine chloride in the
2
4
2
[16–18]
antifibrilatory activities.
Organosulfur compounds
presence of sodium bicarbonate in toluene under reflux
due to their various applications are known as interesting
compounds in the pharmaceutical and chemical indus-
tries. Sulfoxides have very important structures because
they contain S═O bonds and are privileged structural
scaffolds for building pharmacologically and biologically
active molecules as well as because of their unique
properties, such as central chirality at the sulfur, high
configurational stability and the strongly polarized S═O
bond, which have attracted the attention of researchers.
In addition, organic sulfoxides are used as versatile syn-
thetic intermediates in the generation of numerous natu-
for 30 h. Eventually, CoFe O @SiO ‐CPTES‐Guanidine
2
4
2
was treated with Cu(NO ) ⋅6H O in ethanol at reflux
3
2
2
temperature for 24 h to generate the CoFe O @SiO ‐
2
4
2
CPTES‐Guanidine‐Cu(II) catalyst. The protocol is
depicted in Scheme 1.
The synthesized catalyst was characterized using Fou-
rier transform infrared (FT‐IR) spectroscopy, scanning
electron microscopy (SEM), energy‐dispersive X‐ray spec-
troscopy (EDX), vibrating sample magnetometry (VSM),
thermogravimetric analysis (TGA), X‐ray diffraction
(XRD) and inductively coupled plasma optical emission
spectrometry (ICP‐OES).
[19–21]
ral products and biologically active compounds.
In this paper, we report the simple and efficient
The FT‐IR spectra of CoFe O , CoFe O @SiO ,
2
4
2
4
2
synthesis of CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II)
CoFe O @SiO ‐CPTES, CoFe O @SiO ‐CPTES‐Guani-
2
4
2
2
4
2
2
4
2
magnetic nanoparticles, i.e. Cu immobilized on CoFe O4
dine and CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II) are
2
2
4
2
nanoparticles functionalized with guanidine, and their
application in the oxidation of sulfides to sulfoxides as
well as in the synthesis of polyhydroquinolines and 2,3‐
dihydroquinazolin‐4(1H)‐ones under mild conditions.
shown in Figure 1. The FT‐IR spectrum of CoFe O
2
4
2
2
| RESULTS AND DISCUSSION
.1 | Preparation and characterization of
CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II)
2
4
2
In the first step, CoFe O nanoparticles were prepared
2
4
using a mixture of CoCl ⋅4H O, FeCl ⋅6H O and NaOH
2
2
3
2
[22]
dissolved in deionized water under reflux.
In the
next step, the CoFe O4 nanoparticles were coated
2
with tetraethyl orthosilicate (TEOS) to afford
CoFe O @SiO in order to increase the surface area
2
4
2
and chemical stability of the magnetite nanoparticles.
Then, using the reaction of CoFe O @SiO with 3‐
2
4
2
2 4
FIGURE 1 FT‐IR spectra of (a) CoFe O nanoparticles, (b)
chloropropyltriethoxysilane (CPTES), CoFe O @SiO ‐
2 4 2 2 4 2 2 4 2
CoFe O @SiO , (c) CoFe O @SiO ‐CPTES, (d) CoFe O @SiO ‐
2
4
2
CPTES was prepared. Next, guanidine was immobilized
2 4 2
CPTES‐Guanidine and (e) CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II)
SCHEME 1 Stepwise preparation of
CoFe @SiO ‐CPTES‐Guanidine‐Cu(II)
2
O
4
2

HEIDARI AND SHIRI
3 of 11
−
1
shows a broad band at 3383 cm which corresponds to
The amount of copper in the surface of the catalyst
the O─H stretching vibration. Also, two peaks at 590
was measured using ICP‐OES. The value obtained was
2.1049 × 10 mol g .
The SEM observations of the catalyst confirmed that
the particles are approximately spherical. Moreover,
particles of the catalyst were observed at the nanoscale
(Figure 2).
−
1
−3
−1
and 470 cm correspond to the Co─O stretching vibra-
−
1
tion (Figure 1a). The broad band at 1084 cm can be
attributed to Si─O─Si bond stretching vibration
(
Figure 1b). The FT‐IR spectrum of CoFe O @SiO ‐
2
4
2
−
1
CPTES shows two peaks at 2932 and 2952 cm which
are related to C─H stretching vibrations (Figure 1c).
The functionalization with guanidine was confirmed by
the appearance of the peak at 3440 cm that is related
to the NH and NH groups and the peak at 1664 cm
−
1
−
1
2
that can be attributed to C═N bond stretching vibration
Figure 1d). The band of C═N shifting to lower fre-
(
−
1
quency of 1625 cm can be indicative of the Cu(II)
complex being successfully immobilized on the surface
of the functionalized CoFe O @SiO ‐CPTES‐Guanidine
2
4
2
magnetic nanoparticles (Figure 1e).
FIGURE 4 XRD patterns of CoFe
Cu(II) and CoFe
2 4 2
O @SiO ‐CPTES‐Guanidine‐
2 4
O
2 4 2
FIGURE 2 SEM images of CoFe O @SiO ‐CPTES‐Guanidine‐
Cu(II) at different magnifications
FIGURE 5 Magnetization curves for CoFe
CoFe @SiO ‐CPTES‐Guanidine‐Cu(II) (red line) at room
temperature.
2 4
O (blue line) and
2
O
4
2
FIGURE 3 EDX spectrum of CoFe
2
O
4
@SiO
2
‐CPTES‐Guanidine‐
FIGURE
6
2 4 2
TGA thermogram of CoFe O @SiO ‐CPTES‐
Cu(II)
Guanidine‐Cu(II)

4
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HEIDARI AND SHIRI
In another investigation, EDX analysis confirmed
The magnetic properties of CoFe O
and
2
4
elements such as Co, Fe, O, Si, N and Cu in the
CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II) nanoparticles
2
4
2
CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II) catalyst. It can
were investigated using the VSM technique. The magneti-
2
4
2
be concluded that the CoFe O @SiO ‐CPTES‐Guani-
zation curves for CoFe O and CoFe O @SiO ‐CPTES‐
2
4
2
2
4
2
4
2
dine‐Cu(II) nanocatalyst had been successfully synthe-
sized (Figure 3).
Guanidine‐Cu(II) are depicted in Figure 5. According to
the magnetization curves, the saturation magnetization of
−
1
The XRD pattern of CoFe O @SiO ‐CPTES‐Guani-
the nanoparticles decreased from 39.91 emu g in the ini-
2
4
2
−
1
dine‐Cu(II) is shown in Figure 4. Several characteristic
peaks at 2θ = 18.2°, 30.1°, 35.5°, 43.1°, 57.0° and 62.6°
were identified that were assigned to the (111), (220),
tial CoFe O nanoparticle sample to 15.09 emu g in the
2 4
final CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II) catalyst.
2
4
2
The decrease of the saturation magnetization can be related
to the presence of organic compounds on the surface of the
CoFe O @SiO nanoparticle support (Figure 5).
(311), (400), (511) and (440) crystallographic faces of
magnetite CoFe O . As shown in Figure 4, the positions
2
4
2
4
2
of all peaks in the XRD pattern of CoFe O @SiO ‐
The TGA curve of CoFe O @SiO ‐CPTES‐Guanidine‐
2
4
2
2
4
2
CPTES‐Guanidine‐Cu(II)
standard XRD pattern of CoFe O . This pattern showed
that the crystallography of inverse cubic spinel struc-
were
according
to
Cu(II) indicated a weight loss 4% below 200°C which cor-
responds to desorption of physically adsorbed solvents
and surface hydroxyl groups (removal of silanol groups
and solvents). The major amount of weight loss is about
24% between 200 and 820°C and is related to removal of
organic species on CoFe O (Figure 6).
2
4
tures of CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II) is
2
4
2
preserved during modification and functionalization of
CoFe O .
2
4
2 4
a
TABLE 1 Optimization of reaction conditions
b
Entry
Catalyst (mg)
Solvent (ml)
Temperature (°C)
Yield (%)
1
2
3
4
5
6
7
8
9
8
8
8
8
8
8
8
8
8
6
4
2
1
—
2
2
2
PEG
90
79
75
45
80
98
50
65
40
43
99
99
98
81
Trace
98
50
30
DMF
PhMe
90
90
H
2
O
90
Solvent‐free
90
EtOH
Reflux
80
2
EtOH–H O (1:1)
EtOAc
Reflux
Reflux
90
3
CH CN
10
11
12
13
14
15
16
17
Solvent‐free
Solvent‐free
Solvent‐free
Solvent‐free
Solvent‐free
Solvent‐free
Solvent‐free
Solvent‐free
90
90
90
90
120C
60C
r.t.
a
Reactions conditions: 4‐chlorobenzaldehyde (1 mmol, 140 mg), dimedone (1 mmol, 140 mg), ethylacetoacetate (1 mmol, 130 mg) and ammonium acetate
b
(
1.2 mmol, 92.49 mg), solvent (2 ml), time (10 min). Isolated yield.

HEIDARI AND SHIRI
5 of 11
2
.2 | Catalytic studies
dimedone, ammonium acetate and ethylacetoacetate.
The results are summarized in Table 1. As is evident, 2 mg
of CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II), solvent‐free
After preparation and characterization of the
2
4
2
CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II) nanoparticles,
conditions and 90°C were found to be the best conditions
2
4
2
we examined the activity and efficiency of this
for the synthesis of polyhydroquinolines.
nanocatalyst in the synthesis of polyhydroquinolines,
To investigate the generality of the catalytic protocol,
we extended the reaction to a broad spectrum of aromatic
aldehydes under the optimized reaction conditions
2
,3‐dihydroquinazolin‐4(1H)‐ones and in the oxidation
of sulfides to sulfoxides.
(
Scheme 2). The results are summarized in Table 2.
2
.2.1 | Polyhydroquinolines
2
.2.2 | 2,3‐Dihydroquinazoline‐4(1H)‐ones
In order to optimize reaction conditions, various parame-
ters such as solvent, temperature and amount of catalyst
were examined in the reaction of 4‐chlorobenzaldehyde,
To obtain the optimal reaction conditions, various param-
eters such as solvent, temperature and amount of catalyst
SCHEME 2 Synthesis of
polyhydroquinolines catalysed by
2 4 2
CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II)
2 4 2
TABLE 2 Synthesis of polyhydroquinoline derivatives catalysed by CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II)
a
Entry
Aldehyde
4‐ClC CHO
CHO
4‐OMeC
4‐FC
4‐NO
4‐OEtC
4‐COHC
3‐OMeC
3‐NO
3‐OHC
3‐BrC
2‐OMeC
2‐NO
Product
Time (min)
Yield (%)
M.p. (°C)
[
[
[
[
[
[
[
[
[
[
[
[
[
16]
1
2
3
4
5
6
7
7
8
9
6
H
5
2a
2b
2c
2d
2e
2f
10
7
98
95
99
91
95
92
99
88
94
92
95
95
91
231–233
215–216
251–252
189–190
240–241
184–186
299–300
204–205
172–173
219–220
225–228
257–258
201–204
23]
23]
16]
23]
23]
24]
24]
16]
25]
16]
25]
16]
6 5
C H
6
H
5
CHO
CHO
CHO
CHO
CHO
CHO
CHO
CHO
CHO
CHO
CHO
20
15
12
35
20
22
20
30
17
27
18
6
H
5
2 6 5
C H
6
H
5
6
H
5
2g
2g
2h
2i
6
H
5
2 6 5
C H
6
H
5
1
1
1
0
1
2
6
H
5
2j
6
H
5
2k
2l
2 6 5
C H
a
Isolated yield.
SCHEME 3 Synthesis of 2,3‐
dihydroquinazoline‐4(1H)‐one derivatives
catalysed byCoFe O @SiO ‐CPTES‐
2 4 2
Guanidine‐Cu(II)

6
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HEIDARI AND SHIRI
a
TABLE 3 Optimization of reaction conditions
b
Entry
Catalyst (mg)
Solvent (ml)
Temperature (°C)
Yield (%)
1
2
3
4
5
6
7
8
9
10
10
10
10
10
10
10
10
9
DMF
PEG
100
61
50
30
98
40
70
73
20
99
98
80
65
Trace
98
73
43
30
100
PhMe
100
H
2
O
Reflux
Reflux
80
EtOH
EtOH–H
2
O (1:1)
EtOAc
Reflux
Reflux
100
3
CH CN
H
2
H
2
H
2
H
2
H
2
O
O
O
O
O
10
11
12
13
14
15
16
17
8
100
6
100
4
100
—
8
100
H
2
O
O
O
O
80
8
H
H
H
2
60
8
2
2
40
8
r.t.
a
Reaction conditions: anthranilamide (1 mmol, 142.8 mg) and 4‐chlorobenzaldehyde (1 mmol, 140 mg) in the presence of catalyst and solvent (2 ml) for 35 min.
b
Isolated yield.
TABLE 4 Synthesis of 2,3‐dihydroquinazolin‐4(1H)‐one derivatives catalysed by CoFe
2
O
4
@SiO
2
‐CPTES‐Guanidine‐Cu(II)
a
Entry
Aldehyde
4‐ClC CHO
CHO
4‐OMeC
4‐FC
4‐NO
4‐OHC
3‐NO
3‐BrC
3‐OMeC
3‐OHC
2‐OMeC
2‐NO
2‐OHC
Product
Time (min)
Yield (%)
M.p. (°C)
[
[
[
[
[
[
[
[
[
[
[
[
[
23]
1
2
3
4
5
6
7
8
9
6
H
5
4a
4b
4c
4d
4e
4f
35
20
30
35
50
30
45
40
22
25
15
40
18
98
96
98
95
93
99
94
97
91
88
87
98
94
195–197
215–216
183–184
199–200
200–202
279–280
188–189
181–182
146–148
180–181
171–173
185–187
218–219
23]
23]
23]
23]
23]
23]
23]
23]
16]
23]
23]
26]
6 5
C H
6
H
5
CHO
CHO
CHO
CHO
CHO
CHO
CHO
CHO
6
H
5
2 6 5
C H
6
H
5
2
C
6
H
5
4g
4h
4i
6
H
5
6
H
5
1
1
1
1
0
1
2
3
6
H
5
4j
6
H
5
CHO
CHO
CHO
4k
4l
2 6 5
C H
6
H
5
4m
a
Isolated yield.

HEIDARI AND SHIRI
7 of 11
were examined in the reaction of anthranilamide with 4‐
chlorobenzaldehyde (Scheme 3). An amount of 8 mg of
CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II) nanocatalyst in
oxidation of methylphenyl sulfide as a simple model reac-
tion (Scheme 4). Various amounts of CoFe O @SiO ‐
2
4
2
CPTES‐Guanidine‐Cu(II) catalyst were applied at several
temperatures under solvent‐free conditions. The results
are summarized in Table 5. The best results were
obtained when 7 mg of CoFe O @SiO ‐CPTES‐Guani-
2
4
2
water at 80°C were obtained for the optimal conditions
(
Table 3). Subsequently, wide range of 2,3‐
a
dihydroquinazoline‐4(1H)‐one derivatives were prepared
successfully under the optimal conditions. The results
show that all the reactions occurred successfully in high
to excellent yields and in relatively short reaction times.
The results are presented in Table 4.
2
4
2
dine‐Cu(II) catalyst and 0.5 ml of 30% hydrogen peroxide
were used under solvent‐free conditions at 40°C. Results
for the oxidation of various sulfides to sulfoxides are pre-
sented in Table 6.
2.2.3 | Oxidation of sulfides to sulfoxides
2.2.4 | Comparison with other catalysts
To investigate the catalytic activity of the CoFe O @SiO ‐
To compare the efficiency the CoFe O @SiO ‐CPTES‐
2
4
2
2
4
2
CPTES‐Guanidine‐Cu(II) nanocatalyst, we chose the
Guanidine‐Cu(II) nanocatalyst with that of other
catalysts reported in the literature, the results
obtained for the synthesis of polydroquinolines, 2,3‐
dihydroquinazolin‐4(1H)‐ones and sulfoxides using the
CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II) nanoparticles
2
4
2
were compared with the best of the well‐known data
from the literature as outlined in the Table 7. The synthe-
sized nanocatalyst has advantages such as low reaction
time, high catalytic activity and high yields of products.
SCHEME 4 Oxidation of sulfides to sulfoxides catalysed by
CoFe @SiO ‐CPTES‐Guanidine‐Cu(II)
2
O
4
2
a
TABLE 5 Optimization of reaction conditions
b
Entry
Catalyst (mg)
Solvent (ml)
Temperature (°C)
H
2
O
2
(ml)
Yield (%)
1
2
3
4
5
6
7
8
9
9
9
9
9
9
9
9
8
7
6
—
7
7
7
7
EtOH
40
40
40
40
40
40
40
40
40
40
40
60
r.t.
40
40
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
50
35
20
65
96
—
19
95
95
40
NR
95
65
96
89
Ethyl acetate
EtOH–H
CH CN
Solvent‐free
2
O(1:1)
3
2
H O
Acetone
Solvent‐free
Solvent‐free
Solvent‐free
Solvent‐free
Solvent‐free
Solvent‐free
Solvent‐free
Solvent‐free
0.5
0.5
0.5
0.5
0.5
0.6
0.4
1
1
1
1
1
1
0
1
2
4
5
6
a
2 2
Reactions conditions: oxidation of methylphenyl sulfide (1 mmol, 124 mg), using 30% H O in the presence of catalyst and solvent (2 ml) for 20 min.
b
Isolated yield.

8
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HEIDARI AND SHIRI
TABLE 6 Oxidation of sulfides into sulfoxides catalysed by CoFe
2
O
4
@SiO
2
‐CPTES‐Guanidine‐Cu(II) at 40°C under solvent‐free conditions
a
Entry
Aldehyde
Product
Time (min)
Yield (%)
M.p. (°C)
[
27]
1
2
3
4
5
6
7
Methylphenyl sulfide
Benzylphenyl sulfide
Dodecyl sulfide
6a
6b
6c
6d
6f
20
75
60
70
65
80
55
95
93
91
90
90
92
96
Oil
[
27]
118–120
[
28]
65–66
[
[
[
[
27]
Dibutyl sulfide
Oil
Oil
Oil
Oil
27]
27]
27]
Dipropyl sulfide
Diethyl sulfide
6g
6h
Tetrahydrothiophene
a
Isolated yield.
2 4 2
TABLE 7 Comparison of catalytic activity of CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II) with that of other catalysts in the synthesis of
polydroquinolines (entries 1–5), 3,2‐dihydroquinazolin‐4(1H)‐ones (entries 6–10) and sulfoxides (entries 11–15)
Entry
Catalyst
PdCl
[PW11CoO40
Cu‐SPATB/Fe
[TBA] [W
This catalyst
KAl(SO
Conditions
Time (min)
Yield (%)
Ref.
[
[
[
[
29]
30]
31]
32]
1
2
3
4
5
6
7
8
9
2
THF, reflux
240
30
87
80
96
95
96
80
97
81
87
98
95
82
92
88
95
K
7
]
3
CH CN, reflux
3
O
4
PEG‐400, 80°C
Solvent‐free, 110°C
Solvent‐free, 90°C
EtOH, reflux
65
2
6
O
19
]
20
25
This work
[
[
[
[
33]
34]
35]
36]
4
)
2
.E12
H
2
O
300
360
180
150
65
Glycerosulfonic acid
Silica sulfuric acid
SBNPSA
Glycerol, 80°C
H
2
O,80°C
EtOH, reflux
O, 80°C
10
11
12
13
14
15
This catalyst
H
2
This work
[
[
[
[
37]
38]
39]
40]
Mo complexes supported on silica (II)
Silica‐based tungstate
Fe(salen) complex
TsOH
CH
CH
3
3
CN–EtOH (1:1), −10°C
CN–EtOH (1:1), r.t.
720
90
H
H
2
2
O, r.t.
O, r.t.
360
240
20
This catalyst
Solvent‐free, 40°C
This work
2.2.5 | Reusability of catalyst
One of the important benefits of heterogeneous
catalysts is their easy separation and recyclability. In
this regard, the recovery and recyclability of the
magnetic nanocatalyst were evaluated in the model
reaction. At the end of the reaction, CoFe O @SiO ‐
2
4
2
CPTES‐Guanidine‐Cu(II) was collected using an
external magnetic field, washed with ethyl acetate and
dried in an oven at 50°C. The recycled magnetic
nanocatalyst was used for seven times successively in
the model reaction without any significant loss of its
catalytic activity. The results of this work are shown in
Figure 7.
2 4 2
FIGURE 7 Reusability of CoFe O @SiO ‐CPTES‐Guanidine‐
Cu(II) in the synthesise of products 2b, 4b and 6a

HEIDARI AND SHIRI
9 of 11
3
| CONCLUSIONS
by magnetic separation and washed three times with
ethanol.
[
41]
In summary, the obtained results of this study demon-
strated that CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II)
2
4
2
4
.4 | Preparation of CoFe O @SiO ‐CPTES
2
4
2
is a novel, versatile, highly efficient and reusable
heterogeneous catalyst for the synthesis of 2,3‐
dihydroquinazoline‐4(1H)‐ones and polyhydroquinolines
and for the oxidation of sulfides. This catalyst with high
activity could be readily recovered from reaction media
using an external magnet and reused several times with-
out any noticeable loss of activity. Good to excellent
yields, simplicity of operation, high catalytic activity, easy
magnetic separation and reusability of the solid catalyst
are notable advantages of this protocol. As a result of this
study, this protocol can act as an efficient strategy for the
synthesis of biologically and pharmaceutically active
molecules.
In order to prepare CoFe O @SiO ‐CPTES, 1 g of
CoFe O @SiO was dispersed in 50 ml of ethanol–water
2
4
2
2
4
2
(
1:1 v/v) by sonication for 30 min. Then CPTES (2.5 ml)
was added to the reaction and the mixture was stirred
for about 8 h at 40°C. The resulting CoFe O @SiO ‐
CPTES magnetic nanoparticles were isolated by simple
magnetic decantation, washed with ethanol and dried
2
4
2
[
16]
under vacuum at room temperature.
4.5 | Preparation CoFe O @SiO ‐CPTES‐
Guanidine
2
4
2
An amount of 1 g of CoFe O @SiO ‐CPTES was
2
4
2
4
4
| EXPERIMENTAL
.1 | Materials
dispersed in 8 ml of toluene in an ultrasonic bath
for 10 min. Subsequently, guanidine hydrochloride
(0.008 mol) and sodium bicarbonate (0.004 mol) were
added and the mixture was refluxed for 30 h. The
CoFe O @SiO ‐CPTES‐Guanidine thus obtained was
All chemicals were purchased from Merck or Fluka. The
known products were identified by comparison of their
melting points and spectral data with those reported in
the literature. Progress of the reactions was monitored
by TLC using silica gel SILG/UV 254 plates.
2
4
2
separated using a magnetic field, washed with double‐
distilled water until neutrality, further washed twice with
[
42]
CH Cl and dried at room temperature.
2
2
4
.6 | Preparation CoFe O @SiO ‐CPTES‐
2
4
2
Guanidine‐Cu(II)
4
.2 | Preparation of CoFe O4
2
An amount of 1 g of CoFe O @SiO ‐CPTES‐Guanidine as
prepared in the previous step and 2 mmol of Cu
2
4
2
Initially, a mixture of CoCl ⋅6H O (0.005 mol, 1.19 g) and
2
2
FeCl ⋅6H O (0.01 mol, 2.705 g) was dissolved in 50 ml of
3
2
(
NO ) ⋅6H O were added to 50 ml of ethanol and the
3
2
2
distilled water. Then, 3 g of NaOH in 25 ml of deionized
water was dissolved and added dropwise into the reaction
mixture at room temperature. Next, the reaction
mixture was stirred for 1 h at reflux temperature. The
black precipitate of CoFe O nanoparticles was separated
mixture was stirred under reflux for 24 h. Finally,
the resulting CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II)
2
4
2
nanosolid was separated utilizing an external magnet.
The nanomagnetic catalyst was washed several times
2
4
[41]
with ethanol and dried at room temperature.
using a magnetic field, washed four times with distilled
water and twice with ethanol and dried at room
[22]
temperature.
4.7 | General procedure for synthesis of
polyhydroquinolines
4
.3 | Preparation of CoFe O @SiO
A mixture of aldehyde (1 mmol), dimedone (1 mmol),
ethylacetoacetate (1 mmol), ammonium acetate
(1.2 mmol) and CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II)
2
4
2
An amount of 1 g of the CoFe O magnetic nanoparticles
2
4
2
4
2
was dispersed in 10 ml of water by sonication for 30 min.
Then ethanol (25 ml), poly(ethylene glycol) (PEG; 2.65 g),
water (10 ml), ammonia solution (5 ml, 28 wt%) and
TEOS ((1 ml) were added successively into the suspension
solution and were stirred by mechanical stirring at room
temperature for 38 h. The resulting product was collected
(2 mg) was added to a test tube. The obtained reaction
mixture was stirred under solvent‐free conditions at
90°C and the progress of the reaction was followed by
TLC. After completion of the reaction, ethyl acetate was
added to dissolve the target products. Then, the
CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II) catalyst was
2
4
2

10 of 11
HEIDARI AND SHIRI
easily separated from the reaction mixture using an exter-
nal magnet and washed thoroughly with ethyl acetate.
Then, the solvent was evaporated and the product was
recrystallized from ethanol. The pure polyhydroquinoline
derivatives were obtained in excellent yields.
[2] V. Polshettiwar, T. Asefa (Eds), Nanocatalysis Synthesis and
Applications, 1st ed., State University of New Jersey,
Piscataway, NJ 2013.
[3] E. Kolvari, N. Koukabi, M. M. Hosseini, M. Vahidian, E.
Ghobadi, RSC Adv. 2016, 6, 7419.
[4] G. Subias, V. Cuartero, J. Garcia, J. Blasco, S. Lafuerza, S.
Pascarelli, G. Garbarino, Physiol. Rev. 2013, 87, 094.
[
[
5] M. Kooti, E. Nasiri, J. Mol. Catal. A 2015, 406, 168.
4
2
.8 | General procedure for synthesis of
,3‐dihydroquinazolin‐4(1H)‐ones
6] K. Maaz, A. Mumtaz, S. K. Hasanain, A. Ceylan, J. Magn.
Magn.Mater. 2007, 308, 289.
[
[
[
7] I. Sharifi, H. Shokrollahi, M. M. Doroodmand, R. Safi, J. Magn.
Magn. Mater. 2012, 324, 1854.
A
mixture of aromatic aldehyde (1 mmol),
anthranilamide (1 mmol) and CoFe O @SiO ‐CPTES‐
2
4
2
8] D. Carta, M. F. Casula, A. Falqui, D. Loche, G. Mountjoy, C.
Sangregorio, A. Corrias, J. Phys. Chem. 2009, 113, 8606.
Guanidine‐Cu(II) (8 mg) in a round‐bottom flask contain-
ing 2 ml of water was stirred using a magnetic stirrer
at 80°C. The reaction progress was monitored by TLC
9] E. Swatsitang, S. Phokha, S. Hunpratub, B. Usher, A.
Bootchanont, S. Maensiri, P. Chindaprasirt, J. Alloys Compd.
(ethyl acetate–n‐hexane, 2:8). After the time specified in
2016, 664, 792.
Table 4, the reaction mixture was allowed to cool to room
temperature. The catalyst was separated using an external
magnet and washed with ethyl acetate. The reaction
product was extracted from the reaction mixture using
ethyl acetate. Subsequently, the solvent was evaporated
under reduced pressure to afford the crude products.
The pure products were obtained via recrystallization
from ethanol.
[
[
[
10] T. G. Altincekic, I. Boz, A. Baykal, S. Kazan, R. Topkaya, M. S.
Toprak, J. Alloys Compd. 2010, 493, 493.
11] K. K. Senapati, C. Borgohain, P. Phukan, J. Mol. Catal. A 2011,
3
39, 24.
12] R. W. Grimes, A. B. Anderson, A. H. Heuer, J. Am. Chem. Soc.
989, 111, 1.
1
[13] V. Klusa, Cerebrocrast, Drugs Future 1995, 20, 138.
[14] A. Sausins, G. Duburs, Chem Inform. 1988, 19, 22.
[15] A. Mandal, B. K. Patel, Chem. Select 2017, 2, 1717.
4
.9 | General procedure for oxidation of
[16] L. Shiri, S. Zarei, M. Kazemi, D. Sheikh, Appl. Organometal.
Chem. 2018, 32, e3938.
sulfides to sulfoxides
[17] M. Hajjami, F. Ghorbani, Z. Yousofvand, Appl. Organometal.
A mixture of methylphenyl sulfide (1 mmol), H O2
Chem. 2017, 31, e3843.
2
(
(
0.5 ml) and CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II)
7 mg) was stirred at 40°C under solvent‐free conditions.
[18] M. Hajjami, F. Gholamian, RSC Adv. 2016, 6, 87950.
2
4
2
[
[
19] M. Kazemi, M. Ghobadi, Nanotechnol. Rev. 2017, 6, 549.
The reaction progress was monitored by TLC (ethyl
acetate–n‐hexane, 2:8). After completion of the reaction,
the catalyst was separated using an external magnet and
washed with ethyl acetate. Then, the organic solvents
were evaporated, and the corresponding sulfoxides were
obtained in high to excellent yields (90–98%).
20] S. Gan, J. Yin, Y. Yao, Y. Liu, D. Chang, D. Zhu, L. Shi, Org.
Biomol. Chem. 2017, 15, 2647.
[
[
[
[
[
21] M. Nikoorazm, A. Ghorbani‐Choghamarani, H. Mahdavi, S. M.
Esmaeili, Micropor. Mesopor. Mater. 2015, 211, 174.
22] P.‐H. Li, B.‐L. Li, Z.‐M. An, L.‐P. Mo, Z.‐S. Cui, Z.‐H. Zhang,
Adv. Synth. Catal. 2952, 2013, 355.
23] L. Shiri, A. Ghorbani‐Choghamarani, M. Kazemi, Appl.
Organometal. Chem. 2017, 31, e3634.
ACKNOWLEDGEMENT
24] M. Abedini, F. Shirini, M. Mousapour, Res. Chem. Intermed.
2016, 42, 2303.
This work was supported by the research facilities of Ilam
University, Ilam, Iran.
25] A. Ghorbani‐Choghamarani, B. Tahmasbi, Z. Moradi, Appl.
Organometal. Chem. 2017, 31, e3665.
[
26] J. Safari, S. Gandomi‐Ravandi, J. Mol. Catal. A 2014, 390, 1.
27] M. Hajjami, S. Kolivand, Appl. Organometal. Chem. 2016,
ORCID
[
30, 282.
Lotfi Shiri https://orcid.org/0000-0003-0716-6647
[28] T. Tamoradi, M. Ghadermazi, A. Ghorbani‐Choghamarani,
Appl. Organometal. Chem. 2017, 31, e3974.
REFERENCES
[29] M. Saha, A. K. Pal, Tetrahedron Lett. 2011, 52, 4872.
[
1] M. Kazemi, M. Ghobadi, A. Mirzaie, Nanotechnol. Rev. 2018, 7,
3.
[30] M. M. Heravi, K. Bakhtiari, N. M. Javadi, F. F. Bamoharram,
4
M. Saeedi, J. Mol. Catal. A 2007, 264, 50.

HEIDARI AND SHIRI
11 of 11
[
[
[
31] A. Ghorbani‐Choghamarani, B. Tahmasbi, P. Moradi, N.
[41] M. Hajjami, F. Sharifirad, F. Gholamian, Appl. Organometal.
Chem. 2017, 31, e3844.
Havasi, Appl. Organometal. Chem. 2016, 30, 619.
32] A. Davoodnia, M. Khashi, N. Tavakoli‐Hoseini, Chin. J. Catal.
[42] B. Atashkar, A. Rostami, B. Tahmasbi, Catal. Sci. Technol.
2013, 3, 2140. https://doi.org/10.1039/c3cy00190c
2
013, 34, 1173.
33] M. Dabiri, P. Salehi, S. Otokesh, M. Baghbanzadeh, G.
Kozehgary, A. A. Mohammadi, Tetrahedron Lett. 2005, 46,
SUPPORTING INFORMATION
6
123.
34] M. Hajjami, F. Bakhti, E. Ghiasbeygi, Croat. Chem. Acta 2015,
8, 197.
Additional supporting information may be found online
in the Supporting Information section at the end of the
article.
[
[
[
[
[
8
35] M. Dabiri, P. Salehi, M. Baghbanzadeh, M. A. Zolfigol, M.
Agheb, S. Heydari, Catal. Commun. 2008, 9, 785.
36] K. Niknam, N. Jafarpour, E. Niknam, Chin. Chem. Lett. 2011,
2
2, 69.
How to cite this article: Heidari L, Shiri L.
CoFe O @SiO ‐CPTES‐Guanidine‐Cu(II): A novel
and reusable nanocatalyst for the synthesis of 2,3‐
dihydroquinazolin‐4(1H)‐ones and
polyhydroquinolines and oxidation of sulfides. Appl
Organometal Chem. 2019;e4636. https://doi.org/
10.1002/aoc.4636
37] F. Batigalhia, M. Zaldini‐Hernandes, A. G. Ferreira, I.
Malvestiti, Tetrahedron 2001, 57, 9669.
2
4
2
38] B. Karimi, M. Ghoreishi‐Nezhad, J. H. Clark, Org. Lett. 2005,
7, 625.
[
[
39] H. Egami, T. Katsuki, J. Am. Chem. Soc. 2007, 129, 8940.
40] B. Yu, C. X. Guo, C. L. Zhong, Z. F. Diao, L. N. He, Tetrahedron
Lett. 2014, 55, 1818.