A novel and reusable magnetic nanocatalyst developed based on graphene oxide incorporated strontium nanoparticles for the facial synthesis of β-enamino ketones under solvent-free conditions

Article abstract of DOI:10.1002/aoc.4644

A novel magnetic SrFeGO nanocatalyst (NC) was synthesized through a simple sol–gel technique by introducing strontium and iron oxide nanoparticles onto graphene. The synthesized NC was characterized using FT-IR and FE-SEM. Subsequently, the catalytic activity of SrFeGO was tested in a reaction between β-dicarbonyl compounds and aniline derivatives to gain β-enamino ketone derivatives under solvent-free conditions. It was found that SrFeGO NC is a potential catalyst for the synthesis of β-enamino ketones. The β-enamino ketone produced by such reactions could be isolated in high purity without the need for chromatographic purifications. The newly prepared magnetic graphene oxide nanocomposite could be recovered and reused for numerous times with no significant decrease in efficiency. Moreover, the protocol has the advantages of excellent yielding (up to 98%) in short a reaction time, benefitting an easy workup procedure and being environmentally friendly.

Full text of DOI:10.1002/aoc.4644

Received: 19 June 2018
DOI: 10.1002/aoc.4644
Revised: 8 September 2018
Accepted: 21 September 2018
F U L L P A P E R
A novel and reusable magnetic nanocatalyst developed
based on graphene oxide incorporated strontium
nanoparticles for the facial synthesis of β‐enamino
ketones under solvent‐free conditions
Seyyed Rasul Mousavi1 | Hassan Sereshti2 | Hamid Rashidi Nodeh2,3 | Alireza Foroumadi1,4
1 Drug Design and Development Research
A novel magnetic SrFeGO nanocatalyst (NC) was synthesized through a simple
sol–gel technique by introducing strontium and iron oxide nanoparticles onto
graphene. The synthesized NC was characterized using FT‐IR and FE‐SEM.
Subsequently, the catalytic activity of SrFeGO was tested in a reaction between
β‐dicarbonyl compounds and aniline derivatives to gain β‐enamino ketone
derivatives under solvent‐free conditions. It was found that SrFeGO NC is a
potential catalyst for the synthesis of β‐enamino ketones. The β‐enamino
ketone produced by such reactions could be isolated in high purity without
the need for chromatographic purifications. The newly prepared magnetic
graphene oxide nanocomposite could be recovered and reused for numerous
times with no significant decrease in efficiency. Moreover, the protocol has
the advantages of excellent yielding (up to 98%) in short a reaction time,
benefitting an easy workup procedure and being environmentally friendly.
Center, The Institute of Pharmaceutical
Sciences (TIPS), Tehran University of
Medical Sciences, Tehran, Iran
2 Department of Chemistry, Faculty of
Science, University of Tehran, Tehran, Iran
3 Department of Food Science &
Technology, Faculty of Food Industry and
Agriculture, Standard Research Institute
(SRI), Karaj P.O. Box: 31745‐139, Iran
4 Neuroscience Research Center, Institute
of Neuropharmacology, Kerman University
of Medical Sciences, Kerman, Iran
Correspondence
Alireza Foroumadi, Department of
Medicinal Chemistry, Faculty of
Pharmacy and Pharmaceutical Sciences
Research Center, Tehran University of
Medical Sciences, Tehran, Iran.
Email: aforoumadi@yahoo.com
KEYWORDS
graphene oxide, magnetic nanocatalyst, solvent‐free, strontium, β‐enamino ketone
1 | INTRODUCTION
employed for the preparation of some biological mole-
cules with anti‐inflammatory, anti‐convulsant, antitumor
β‐enamino ketones are chemical compounds character-
ized by their amino group linked through a C=C to a car-
bonyl group. The amination of β‐dicarbonyl compounds
leads to the formation of β‐enamino ketones. This trans-
formation is widely used in chemistry and is an important
reaction for the synthesis of a highly versatile class of
intermediates for the synthesis of several biologically
important natural products such as aminols, alkaloids
and peptides.[1–4] Hence, β‐enamino ketones are valuable
precursors in organic synthesis as they combine the func-
tions of enamine's nucleophilicity and enone's electrophi-
licity.[5,6] Furthermore, such compounds are beneficial
synthons for synthesizing various pharmaceuticals and
bioactive heterocycles.[7–10] Especially, they have been
and antibacterial activities.[11–14] Therefore, the synthesis
of β‐enamino ketones has received a great deal of atten-
tion. A variety of synthetic procedures for β‐enamino
ketones have been developed using a different range of
catalysts.[15–44]
However, some of the reported methods suffer from
disadvantages such as long reaction time, high catalyst
loading, use of solvents, and deactivation of catalyst on
the repeated use. Hence, there is a need to explore and
develop an efficient and environmentally benign protocol
for the synthesis of β‐enamino ketones using a heteroge-
neous reusable catalyst.
Catalytic systems are generally categorized into two
classes of homogeneous and heterogeneous systems.
Appl Organometal Chem. 2018;e4644.
wileyonlinelibrary.com/journal/aoc
© 2018 John Wiley & Sons, Ltd.
1 of 9
https://doi.org/10.1002/aoc.4644

2 of 9
MOUSAVI ET AL.
High selectivity, catalytic activity and turnover numbers
(TON) in a chemical process are some advantages of
homogeneous catalysts. However, compared to heteroge-
neous catalytic systems, it is difficult for homogeneous
catalytic systems to be isolated from the reaction
media.[45,46] Heterogenization of active molecules is an
interesting way to overcome the problem of homo-
geneous catalytic systems. This is achieved by
functionalization of solid supports. Heterogeneous cata-
lytic systems have gained a noticeable attention in green
and sustainable chemistry. Moreover, the mentioned cat-
alytic systems are used to reduce and sometimes remove
the pollution and other byproducts from chemical and
refining processes.[47–49] Nevertheless, the catalytic acti-
vity of heterogeneous catalysts is usually low. This is
mainly because the active sites in heterogeneous catalytic
systems are not as accessible as in homogeneous catalytic
systems.
and superior stability when compared to the other sup-
ported and unsupported counterparts.[58,63–65] In this
regards, carbon materials, such as graphene, have been
considered as an interesting support due to their large
surface area, thermal and chemical stability, and active
cites.[51,66,67] The combination of nanocarbon materials
and heterogeneous catalytic systems is an important
key to the significant activity and reusability of the
catalysts.
Regarding the importance of this type of catalysts, a
strontium doped magnetic graphene nanocomposite
(SrFeGO NC) was synthesized, and its catalytic activity
was tested for synthesizing β‐enamino ketones from ace-
tyl acetone and anilines under solvent‐free conditions
(Scheme 1). To the best of our knowledge, the application
of SrFeGO NCs for the synthesis of β‐enaminones has not
yet been investigated.
The gap between homogeneous and heterogeneous
catalytic systems could be covered by nanocatalysts.[50,51]
Since, recently nanomaterials with wide range of appli-
cation,[52–54] have been successfully used as catalysts.[55–57]
Nanocatalysts show the activity and selectivity as high
as homogeneous systems and the reusability as efficient
as heterogeneous systems. Such catalysts have recently
been used to catalyze organic reactions. Chemists have
recently introduced many kinds of support catalyst mate-
rials such as gold, silica, zeolite and carbon.[45,58] Among
the various support materials used for the preparation of
heterogeneous catalyst systems, magnetic nanoparticles
(MNPs) have a particular importance because of their
availability, high stability and ability to adjoin organic
groups to their surface with strong bindings.[59–62] More
importantly, due to the magnetic nature of the catalyst,
it could be easily recovered using an external magnetic
field. Consequently, the isolation of the final product
can be possible by a simple decantation. In addition,
such catalysts also showed better reactivity, selectivity
2 | EXPERIMENTAL
2.1 | General
All solvents, chemicals and reagents were purchased
from Merck, Fluka and Aldrich chemical companies.
Melting points were measured on an Electrothermal
9100 apparatus. All reactions and the purity of the
products were monitored by thin‐layer chromatography
(TLC) on F254 aluminium plates coated with silica gel
(Merck) using petroleum ether/ethyl acetate (7:3) as the
eluent solvent. The spots were detected under UV light.
FT‐IR spectra were recorded on a Bruker Equinox 55
1
FT‐IR spectrometer (Bremen, Germany). The H NMR
spectra were recorded on a Bruker NMR‐500 MHz spec-
trometer. Field emission scanning electron microscope
(FE‐SEM) equipped with EDX elemental analysis from
MIRA3 TESCAN (Prague, Czech Republic) was used for
surface morphology and elemental composition analysis
of the SrFeGO NCs.
SCHEME 1 SrFeGO NC Catalyzed
synthesis of β‐enamino ketones

MOUSAVI ET AL.
3 of 9
J = 7.1 Hz, 2H, Ar‐H), 8.21 (d, J = 7.2 Hz, 2H, Ar‐H),
12.79 (s, 1H, NH).
2.2 | Preparation of SrFeGO
nanocomposite
4‐((2‐Hydroxyphenyl)amino)pent‐3‐en‐2‐one
(3l):
Graphene oxide was prepared according to our previously
published work.[68] Iron oxide based graphene oxide
(FeGO) was synthesized as follows. About 0.2
Pale yellow solid; yield: (95%); 1H NMR (500 MHz,
DMSO): δ = 1.95 (s, 3H, CH3), 2.13 (s, 3H, CH3), 5.18
(s, 1H, H‐3), 7.78 (t, J = 7.5 Hz, 1H, Ar‐H), 6.92 (d,
J = 7.6 Hz, 1H, Ar‐H), 7.01 (t, J = 7.3 Hz, 1H, Ar‐H),
7.15 (d, J = 7.6 Hz, 1H, Ar‐H), 9.91 (s, 1H, OH), 12.15
(s, 1H, NH).
g
FeCl3.6H2O and 0.4 g FeCl2.4H2O are dispersed in
50 mL distilled water and o.5 g graphene oxide was added
and sonicated for 30 min. Then, under vigorous stirring,
2 mL ammonia solution (25%) was added to the mixture.
After 5 hr, the supernatant was decanted and the black
participate was washed with excess water before being
oven dried at 80 °C for 24 hr.
The strontium nanoparticle‐decorated graphene oxide
(SrFeGO NC) was prepared as follows; briefly, 1 g freshly
prepared FeGO was added into 0.1 M of strontium nitrate
solution in distilled water and then sonicated for 30 min.
Thereafter, solution's pH was set at 9–10 and the reaction
temperature was set at 45 °C. The mixture was stirred vig-
orously for 1 h and then it was kept at 120 °C for 24 hr.
Lastly, the obtained product (SrFeGO NC) was washed
with excess distilled water by the assistance of an external
magnet before being dried at 80 °C for 24 hr.
4‐((2‐Chlorophenyl)amino)pent‐3‐en‐2‐one (3m): Pale
1
yellow solid; yield: (90%); H NMR (500 MHz, DMSO):
δ = 1.95 (s, 3H, CH3), 2.13 (s, 3H, CH3), 5.21 (s, 1H, H‐
3), 7.78 (t, J = 7.5 Hz, 1H, Ar‐H), 7.15 (m, 1H, Ar‐H),
7.20 (dd, J = 8.0, 1.5 Hz, 1H, Ar‐H), 7.24 (dd, J = 7.5,
1.5 Hz, 1H, Ar‐H), 7.44 (dd, J = 8.0, 1.5 Hz, 1H, Ar‐H),
12.38 (s, 1H, NH).
4‐((2,6‐Dichlorophenyl)amino)pent‐3‐en‐2‐one (3n):
1
White solid; yield: (90%); H NMR (500 MHz, CDCl3):
1.95 (s, 3H, CH3), 2.00 (s, 3H, CH3), 5.31 (s, 1H, H‐3),
6.95 (d, J = 8.6 Hz, 2H, Ar‐H), 7.38 (d, J = 8.1 Hz, 2H,
Ar‐H), 7.19 (t, J = 8.0 Hz, 1H, Ar‐H), 12.04 (s, 1H, NH).
3‐((4‐Chlorophenyl)amino)‐5,5‐dimethylcyclohex‐2‐
en‐1‐one (4b): Yellow solid Yield: (94%) 1H NMR
(500 MHz, DMSO): 1.09 (s, 6H, CH3), 2.10 (s, 2H, CH2),
2.31 (s, 2H, CH2), 5.45 (s, 1H, CH), 6.50 (s, 1H, NH), 7.27
(d, J = 7.6 Hz, 2H, Ar‐H), 7.50 (d, J = 7.6 Hz, 2H, Ar‐H).
5,5‐Dimethyl‐3‐(p‐tolylamino)cyclohex‐2‐en‐1‐one (4d):
2.3 | General procedure for the synthesis
of β‐enamino ketone derivatives
1
A mixture of β‐diketone (1 mmol), amine (1 mmol), and
SrFeGO NC (0.02 g) was stirred under solvent‐free condi-
tions at 110 °C for an appropriate time as shown in
Table 3. After monitoring the completion of the reaction
with TLC (petroleum ether/ethyl acetate, 7:3), the reac-
tion mixture was decanted an eluted using hot ethanol
(5 mL). Then, the catalyst was separated using an exter-
nal magnet. After separation of the catalyst, the products
were obtained by recrystallization using ethanol solution.
Yellow solid; yield: (89%); H NMR (500 MHz, CDCl3):
1.10 (s, 6H, CH3), 2.17 (s, 2H, CH2), 2.30 (s, 3H, CH3),
2.33 (s, 2H, CH2), 5.50 (s, 1H, CH), 6.60 (s, 1H, NH),
7.11 (d, J = 7.60 Hz, 2H, Ar‐H), 7.19 (d, J = 7.60 Hz,
2H, Ar‐H).
3‐(Phenylamino)cyclohex‐2‐en‐1‐one (5a): Yellow
1
solid; yield: (97%); H NMR (500 MHz,CDCl3): 1.76 (t,
J = 6.1 Hz, 2H, CH2), 2.21 (t, J = 6.1 Hz, 2H, CH2), 2.50
(m, 2H, CH2), 5.55 (s, 1H, CH), 6.60 (s, 1H, NH),
7.15–7.22 (m, 3H, Ar‐H) 7.42 (t, J = 7.3 Hz, 2H, Ar‐H).
3‐((4‐Methoxyphenyl)amino)cyclohex‐2‐en‐1‐one (5d):
2.4 | Characterization of some
representative and new compounds
1
Yellow solid; yield (94%); H NMR (500 MHz, CDCl3):
1.92 (t, J = 6.4 Hz, 2H, CH2), 2.26 (t, J = 6.4 Hz, 2H,
CH2), 2.51 (m, 2H, CH2), 3.79 (s, 3H, OCH3), 5.57 (s,
1H, CH), 6.62 (s, 1H, NH), 7.10–7.19 (m, 3H, Ar‐H) 7.35
(t, J = 7.3 Hz, 2H, Ar‐H).
4‐(Phenylamino)pent‐3‐en‐2‐one (3a): Pale yellow solid;
1
yield: (96%); H NMR (500 MHz, DMSO): δ = 2.02 (s,
6H, CH3), 5.89 (s, 1H, H‐3), 7.20 (d, J = 7.0 Hz, 2H, Ar‐
H), 7.38 (d, J = 7.0 Hz, 2H, Ar‐H), 7.43 (d, J = 7.0 Hz,
1H, Ar‐H), 12.41 (s, 1H, NH).
4‐(p‐Tolylamino)pent‐3‐en‐2‐one (3c): Pale yellow
solid; yield: (92%); 1H NMR (500 MHz, CDCl3): 1.96
(s, 3H, CH3), 2.07 (s, 3H, CH3), 2.31 (s, 3H, CH3),
5.19 (s, 1H, H‐3), 6.95 (d, J = 8.6 Hz, 2H, Ar‐H),
7.42 (d, J = 8.6 Hz, 2H, Ar‐H), 12.40 (s, 1H, NH).
4‐((4‐Nitrophenyl)amino)pent‐3‐en‐2‐one (3i): Yellow
3 | RESULTS AND DISCUSSION
Considering the need for an easy, clean and green
recovery for the heterogeneous solid acid catalysts, for
the first time, we propose a nano strontium doped
magnetic graphene nanocomposite (n‐SrFeGO NC). The
synthesized nanocatalyst was characterized using conve-
nient methods including FT‐IR, FE‐SEM and EDX.
1
solid; yield: (93%); H NMR (500 MHz, CDCl3): 2.16 (s,
3H, CH3), 2.21 (s, 3H, CH3), 5.35 (s, 1H, H‐3), 7.19 (d,

4 of 9
MOUSAVI ET AL.
3.1 | Catalyst characterization
3.1.1 | FT‐IR spectroscopy
Vibrational structure of the newly synthesized
nanocatalyst (n‐SrFeGO NCs) was investigated using FT‐
IR spectroscopy (Figure 1). The IR spectra represent
several bands in the range of 450–3700 cm−1. The charac-
teristics bands of strontium nanoparticles (Sr–O) appear
around 460 and 690 cm−1. The band at 3620 cm−1 is prob-
ably corresponding to unreacted hydroxide (OH−) in
metal hydroxide as M(OH)3.[76,77] Iron oxide IR peak
(Fe–O) is observed at 556 cm−1. This is the key factor in
the magnetic material, therefore, its presence denotes the
successful magnetization of the nanocomposite. Addition-
ally, the extra peaks at 3434, 2921/2848, 1769, 1450 and
1208 cm−1 are respectively corresponding to O–H
(stretching vibration), C–H, C=C/C‐C and C–OH of
graphene oxide. Hence, the IR spectra clarify the presence
of magnetic iron oxide, strontium nanoparticles and
graphene oxide in the structure of SrFeGO nanocatalyst.
FIGURE 2 FE‐SEM micrograph of the synthesized SrFeGO
nanoctalyst
3.1.2 | FE‐SEM microscopy
elemental composition of SrFeGO nanocatalyst was
studied using the EDX technique and the weight percent
values obtained were approximately 32, 23, 29 and 14%
for C, O, Fe and Sr, respectively.
The surface morphology and elemental composition of
the SrFeGO nanocatalyst were analyzed using FE‐SEM
microscopy and energy‐dispersive X‐ray spectroscopy
(EDX). The micrograph in Figure 2 depicts the large
smooth and uniform sheets corresponding to graphene
oxide. Besides, the micrograph clearly shows the nano‐
sized particles are well dispersed on the surface of
graphene oxide sheets. It is clear that the sheet structure
of graphene oxide has avoided the aggregations of nano-
particles. The observed nanoparticles are the mixture of
magnetic iron oxide and strontium nanoparticles. The
3.2 | Catalytic performances in the
synthesis of β‐enamino ketones
After characterization, the catalytic activity of SrFeGO
NCs was examined in the synthesis of β‐enamino ketone
derivatives using Scheme 1. The condensation of acetyl
acetone and aniline was chosen as the model reaction
and the effect of the catalyst amount was investigated.
The results have been listed in Table 1. Also, different cir-
cumstances (catalyst amount, solvent and temperature)
were applied in order to optimize the reaction conditions.
In this regard, to minimize or even avoid the formation of
byproducts and to achieve an agreeable yield for the
desired product, the reaction was optimized by varying
the amount of catalyst (5, 10, 15, 20, 25 and 30 mg) under
the reaction conditions at 70 °C. The obtained results
show that in the presence of SrFeGO NCs the reaction
proceeded to produce in a good yield; in the absence of
the catalyst, the reaction did not progress very well and
the yield product was trace. Therefore, the results in
Table 1 indicate that the optimum amount of the catalyst
is 20 mg. Notably, increasing this amount did not show
any significant change in the yield and time of reaction.
In the next step, the same reaction in the presence of
20 mg of SrFeGO NCs was accomplished at different
FIGURE 1 FT‐IR spectrum of SrFeGO NC

MOUSAVI ET AL.
5 of 9
TABLE 1 Optimization of model reaction using different amounts of catalysta
Entry
Catalyst (mg)
Time (h)
Yield (%)b
1
2
3
4
5
6
7
‐
5
24
10
10
5
Trace
59
10
15
20
25
30
73
78
2
86
2
85
16
86
aThe reaction was carried out using acetyl acetone (1 mmol) and aniline (1 mmol) in the presence of different amount of catalyst under solvent‐free conditions.
bYield refers to the pure isolated product.
temperatures under solvent‐free conditions to assess the
effect of temperature on the reaction yield (Table 2).
The results summarized in Table 2 show that the yield
increased as the reaction temperature was raised. At
110 °C, the product was obtained in high yield within
45 min (Table 2, entry 5). Any further increase in the
temperature and time did not improve the product yield
(Table 2, entries 6 and 7).
were the optimum conditions for synthesizing β‐enamino
ketone derivatives. The present approach offers several
advantages such as environmental benignity, simple
work‐up, excellent yield of products, short reaction time
as well as recoverability and reusability of the catalyst.
Encouraged by the remarkable results obtained from
the optimized conditions, and in order to explore the
scope and general applicability of the proposed
β‐enamination reaction of acetylacetone, several
substituted aromatic amines were reacted with acetyl
The results of Tables 1 and 2 show that 20 mg of
SrFeGO NCs and 110 °C under solvent‐free conditions
TABLE 2 Influence of temperature on the model reaction for the synthesis of β‐enaminon (3a)a
Entry
Temperature (°C)
Time (h)
Yield (%)b
1
2
3
4
5
6
7
70
80
2
86
89
89
92
96
95
94
2
90
1.5
1
100
110
120
130
0.75
0.75
0.9
aReaction conditions: Acetyl acetone (1 mmol), aniline (1 mmol), no solvent.
bIsolated yields.

6 of 9
MOUSAVI ET AL.
acetone in the presence of 20 mg SrFeGO NC at 110 °C
under the solvent‐free conditions. The results are shown
in Table 3. As can be seen in Table 3, in all cases, the
reaction proceeded smoothly to give corresponding
β‐enamino ketone derivatives with favorable yields. The
reaction with aromatic amines carrying electron‐donating
or electron withdrawing groups gave the corresponding
products with good yields and high purity.
To further determine the scope of the procedure,
various cyclic β‐dicarbonyl compounds such as 5,5‐
dimethyl‐1,3‐cyclohexanedione and 1,3‐cyclohexadione
were surveyed under the same reaction conditions. The
obtained results are summarized in Table 3. The reaction
proceeded smoothly to give corresponding β‐enamino
ketone derivatives with favorable yields.
the reported catalysts in the reaction between amines
and acetyl acetone for the synthesis of β‐enaminones.
The comparison results presented in Table 4 show that
SrFeGO NC is more or less superior compared with
previously reported catalytic systems in terms of easy
separability, high activity and recyclability, in addition
to high product yields in a short reaction time under neat
conditions. These results considerably verify the high effi-
ciency of the presented catalyst.
3.3 | Reusability of the catalyst
One of the most important advantages of heterogeneous
catalysis is the possibility of reusing the catalyst without
loss of activity after a simple filtration. Moreover, from
the “green” chemistry perspective, efficient recovery and
reuse of the catalyst are highly desirable. Therefore, the
recovery and reusability of the catalyst were investigated
To show the merits of the present work in comparison
with the reported results in the literature, we compared
the results from SrFeGO NC catalyst with those from
TABLE 3 Scope of the SrFeGO nanocomposite catalyzed β‐enamination of β‐dicarbonyl compounds
Substrate
R
Product
Time (h)
Yield (%)a
M.p (°C)
M.p (°C)[Ref]
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1b
1b
1b
1b
1b
1b
1c
1c
1c
1c
H
3a
3b
3c
3d
3e
3f
0.75
1.5
0.7
1
96
86
92
91
97
86
97
88
93
94
80
98
90
90
95
94
92
89
93
95
97
90
91
94
48–50
39–41
47–49[69]
38–39[70]
58–59[70]
71–72[15]
49–51[71]
50–51[70]
39–40[43]
60–62[29]
142–143[43]
41–43[70]
62–63[72]
Newb
2‐CH3
4‐CH3
2‐Br
57–59
69–71
4‐Br
0.8
2
52
2‐OCH3
3‐Cl
51–53
3 g
3 h
3i
1.75
1
39–41
4‐Cl
61–62
4‐NO2
4‐OCH3
3‐CF3
2‐OH
2‐Cl
1.5
1.5
4
140–142
40–42
3j
3 m
3 l
3 k
3n
4a
4b
4c
4d
4e
4f
60–62
0.9
1
48–50
65–67
Newb
Newb
2,6‐Cl2
H
1.5
0.8
1.5
1
38–40
182–184
212
183–184[73]
209–210[73]
246–247[74]
203–204[75]
236–237[74]
191–192[75]
176–178[73]
148–150[69]
192–194[69]
165–167[73]
4‐Cl
4‐NO2
4‐CH3
2‐OH
4‐OCH3
H
247–249
202–204
234–236
192–194
175–177
148–150
190–191
166–168
2
0.75
1.5
1
5a
5b
5c
5d
4‐CH3
4‐Cl
1.5
1.75
2
4‐OCH3
aIsolated yield.
bThe new compounds synthesized in this work.

MOUSAVI ET AL.
7 of 9
TABLE 4 Comparison of SrFeGO NCs with other reported catalysts for the synthesis of β‐enaminones
Compound
3a
Catalyst/Conditions
Time (min)
Yield (%)
[Ref]
[18]
[78]
[73]
[38]
[79]
NbOPO4/Solvent‐free, 50 °C
P2O5/SiO2/Solvent‐free, 80 °C
Fe (OTf)3/Solvent‐free, r.t
Bi (TFA)3‐TBAB/Solvent‐free, r.t
NiO/Ultrasound sonication
SrFeGO NCs/Solvent‐free, 110 °C
90
10
4
85
85
90
99
90
96
Immediately
20
45
This work
[18]
[78]
[73]
[38]
[79]
3e
3 h
3i
NbOPO4/Solvent‐free, 50 °C
P2O5/SiO2/Solvent‐free, 80 °C
Fe (OTf)3/Solvent‐free, r.t
Bi (TFA)3‐TBAB/Solvent‐free, r.t
NiO/Ultrasound sonication
SrFeGO NCs/Solvent‐free, 110 °C
‐
‐
‐
20
‐
48
‐
‐
‐
85
‐
97
This work
[18]
[78]
[73]
[38]
[79]
NbOPO4/Solvent‐free, 50 °C
P2O5/SiO2/Solvent‐free, 80 °C
Fe (OTf)3/Solvent‐free, r.t
Bi (TFA)3‐TBAB/Solvent‐free, r.t
NiO/Ultrasound sonication
SrFeGO NCs/Solvent‐free, 110 °C
‐
‐
5
‐
20
60
‐
‐
94
‐
90
88
This work
[18]
[78]
[73]
[38]
[79]
NbOPO4/Solvent‐free, 50 °C
P2O5/SiO2/Solvent‐free, 80 °C
Fe (OTf)3/Solvent‐free, r.t
Bi (TFA)3‐TBAB/Solvent‐free, r.t
NiO/Ultrasound sonication
SrFeGO NCs/Solvent‐free, 110 °C
270
10
10
‐
20
90
54
80
76
‐
88
93
This work
in the β‐enamination reaction of acetylacetone. After com-
pletion of the reaction, 3 mL ethanol was added to the
reaction mixture. The catalyst was separated by an exter-
nal magnet, washed with hot ethanol or acetone and dried
in an oven (Figure 3). Afterwards, the recovered catalyst
was used in the next run. The results of five consecutive
runs showed that the catalyst can be reused for 5 times
with no significant loss in its activity (Figure 4).
4 | CONCLUSION
FIGURE 3 Magnetic separation of SrFeGO NC using an external
magnet
In conclusion, we have proposed a new, efficient and
environmentally friendly protocol for the synthesis of
β‐enamino ketones using a novel SrFeGO nanocatalyst
as a promoter without using any toxic co‐catalyst or sol-
vent under solvent‐free conditions. The presented strategy
is an inexpensive and useful addition to synthetic organic
chemistry, and utilizes available starting materials to
access a wide variety of β‐enamino ketones with a little
effort. The other remarkable features of this protocol are
simplicity, high yield of desired product, a shorter reac-
tion time and ease of separation of catalyst which make
this protocol a novel, convenient and effective one. The
synthesized SrFeGO NC can be easily recycled and reused
without any significant loss in catalytic activity.
Moreover, the sol–gel technique that was used in the
FIGURE 4 Reusability of SrFeGO NC as catalyst for the
synthesis of 3a

8 of 9
MOUSAVI ET AL.
[20] G. Bartoli, M. Bosco, M. Locatelli, E. Marcantoni, P.
preparation of the SrFeGO NC is a simple method and
provides the nanocatalyst through a solid‐state reaction.
Melchiorre, L. Sambri, Synlett 2004, 2004, 239.
[21] Z.‐H. Zhang, T.‐S. Li, J.‐J. Li, Catal. Commun. 2007, 8, 1615.
[22] D. Astruc, F. Lu, J. R. Aranzaes, Angew. Chemie Int. Ed. 2005,
44, 7852.
ACKNOWLEDGMENTS
The financial support of this work was done by the Iran's
National Elites Foundation. The Tehran University of
Medical Sciences is gratefully acknowledged.
[23] H. Wang, J. Miao, Chinese J. Org. Chem. 2007, 27, 266.
[24] J. Lin, L.‐F. Zhang, Monatshefte für Chemie‐Chemical Mon.
2007, 138, 77.
[25] R. A. Laskar, N. A. Begum, M. H. Mir, S. Ali, A. T. Khan,
Tetrahedron Lett. 2013, 54, 436.
ORCID
[26] X. Chen, J. She, Z.‐C. Shang, J. Wu, P. Zhang, Synth. Commun.
2009, 39, 947.
Alireza Foroumadi http://orcid.org/0000-0003-2416-5611
[27] J. S. Yadav, V. N. Kumar, R. S. Rao, A. D. Priyadarshini, P. P.
Rao, B. V. S. Reddy, K. Nagaiah, J. Mol. Catal. A: Chem. 2006,
256, 234.
REFERENCES
[1] C. M. Kascheres, J. Braz. Chem. Soc. 2003, 14, 945.
[2] J. D. White, D. C. Ihle, Org. Lett. 2006, 8, 1081.
[3] C. Cimarelli, G. Palmieri, J. Org. Chem. 1996, 61, 5557.
[28] G.‐C. Li, J. Chem. Res. 2007, 2007, 696.
[29] Z.‐H. Zhang, L.‐M. Song, J. Chem. Res. 2005, 2005, 817.
[30] M. Kidwai, S. Bhardwaj, N. K. Mishra, V. Bansal, A. Kumar, S.
Mozumdar, Catal. Commun. 2009, 10, 1514.
[4] O. David, J. Blot, C. Bellec, M.‐C. Fargeau‐Bellassoued, G.
Haviari, J.‐P. Célérier, G. Lhommet, J.‐C. Gramain, D.
Gardette, J. Org. Chem. 1999, 64, 3122.
[31] G.‐C. Li, Monatshefte für Chemie/Chemical Mon. 2008, 139, 789.
[32] F. Xu, H.‐X. Lv, J.‐P. Wang, Y.‐P. Tian, J.‐J. Wang, J. Chem. Res.
2008, 2008, 707.
[5] R. K. Vohra, J.‐L. Renaud, C. Bruneau, Collect. Czech. Chem.
Commun. 2005, 70, 1943.
[33] H. T. S. Braibante, M. E. F. Braibante, G. B. Rosso, D. A.
[6] C. V. Stevens, A. Meriggi, K. Booten, Biomacromolecules 2001,
2, 1.
Oriques, J. Braz. Chem. Soc. 2003, 14, 994.
[34] C. P. Cartaya‐Marin, D. G. Henderson, R. W. Soeder, A. J.
Zapata, Synth. Commun. 1997, 27, 4275.
[7] I. O. Edafiogho, J. A. Moore, M. S. Alexander, K. R. Scott,
J. Pharm. Sci. 1994, 83, 1155.
[35] U. U. Indulkar, S. R. Kale, M. B. Gawande, R. V. Jayaram,
Tetrahedron Lett. 2012, 53, 3857.
[8] J. P. Michael, C. B. De Koning, D. Gravestock, G. D. Hosken, A.
S. Howard, C. M. Jungmann, R. W. M. Krause, A. S. Parsons, S.
C. Pelly, T. V. Stanbury, Pure Appl. Chem. 1999, 71, 979.
[36] H. Eshghi, S. M. Seyedi, E. Safaei, M. Vakili, A. Farhadipour,
M. Bayat‐Mokhtari, J. Mol. Catal. A: Chem. 2012, 363, 430.
[9] C. J. C. Connolly, J. M. Hamby, M. C. Schroeder, M. Barvian,
G. H. Lu, R. L. Panek, A. Amar, C. Shen, A. J. Kraker, D. W.
Fry, Bioorg. Med. Chem. Lett. 1997, 7, 2415.
[37] J. Sun, Z. Dong, P. Li, F. Zhang, S. Wei, Z. Shi, R. Li, Mater.
Chem. Phys. 2013, 140, 1.
[38] M. M. Khodaei, A. R. Khosropour, M. Kookhazadeh, Can. J.
Chem. 2005, 83, 209.
[10] M. Uda, A. Momotake, T. Arai, Org. Biomol. Chem. 2003, 1,
1635.
[39] C. R. Hauser, G. A. Reynolds, J. Am. Chem. Soc. 1948, 70, 2402.
[11] N. N. Salama, K. R. Scott, N. D. Eddington, Biopharm. Drug
Dispos. 2004, 25, 227.
[40] Y. Zhao, J. Zhao, Y. Zhou, Z. Lei, L. Li, H. Zhang, New J. Chem.
2005, 29, 769.
[12] A. C. Spivey, R. Srikaran, C. M. Diaper, D. J. Turner, Org.
Biomol. Chem. 2003, 1, 1638.
[41] F. Epifano, S. Genovese, M. Curini, Tetrahedron Lett. 2007,
48, 2717.
[13] R. S. Bhosale, P. A. Suryawanshi, S. A. Ingle, M. N. Lokhande,
S. P. More, S. B. Mane, S. V. Bhosale, R. P. Pawar, Synlett 2006,
2006, 933.
[42] A. Arcadi, G. Bianchi, S. Di Giuseppe, F. Marinelli, Green
Chem. 2003, 5, 64.
[43] Z. Zhang, L. Yin, Y. Wang, Adv. Synth. Catal. 2006, 348, 184.
[14] N. D. Eddington, D. S. Cox, M. Khurana, N. N. Salama, J. P.
Stables, S. J. Harrison, A. Negussie, R. S. Taylor, U. Q. Tran,
J. A. Moore, Eur. J. Med. Chem. 2003, 38, 49.
[44] K. D. Bhatte, P. J. Tambade, K. P. Dhake, B. M. Bhanage, Catal.
Commun. 2010, 11, 1233.
[45] H. Heeres, R. Handana, D. Chunai, C. B. Rasrendra, B.
[15] L.‐F. Zhang, S.‐T. Yang, Russ. J. Org. Chem. 2009, 45, 18.
[16] B. Štefane, S. Polanc, Synlett 2004, 2004, 698.
Girisuta, H. J. Heeres, Green Chem. 2009, 11, 1247.
[46] D. R. Rolison, Science (80‐.) 2003, 299, 1698.
[17] Z.‐H. Zhang, J.‐Y. Hu, J. Braz. Chem. Soc. 2006, 17, 1447.
[47] C. A. Witham, W. Huang, C.‐K. Tsung, J. N. Kuhn, G. A.
Somorjai, F. D. Toste, Nat. Chem. 2010, 2, 36.
[18] F. Wodtke, F. R. Xavier, S. R. Mendes, A. R. M. de Oliveira, R.
A. Gariani, Tetrahedron Lett. 2017, 58, 231.
[48] M. Boudart, Chem. Rev. 1995, 95, 661.
[19] M. M. Khodaei, A. R. Khosropour, M. Kookhazadeh, Synlett
2004, 2004, 1980.
[49] M. S. Holm, S. Saravanamurugan, E. Taarning, Science (80‐.)
2010, 328, 602.

MOUSAVI ET AL.
9 of 9
[50] V. Polshettiwar, R. Luque, A. Fihri, H. Zhu, M. Bouhrara, J.‐M.
Basset, Chem. Rev. 2011, 111, 3036.
[68] H. Rashidi Nodeh, W. A. Wan Ibrahim, I. Ali, M. M. Sanagi,
Environ. Sci. Pollut. Res. 2016, 23, 9759.
[51] O. Mohammadi, M. Golestanzadeh, M. Abdouss, New J. Chem.
2017, 41, 11471.
[69] K. Prabakaran, M. Sivakumar, M. S. Perumal, Chemistry Select
2017, 2, 2363.
[52] M. Devaraj, R. Saravanan, R. Deivasigamani, V. K. Gupta, F.
[70] Y.‐H. Liu, P. Wang, G.‐T. Cheng, Monatshefte für Chemie‐
Chemical Mon. 2013, 144, 191.
Gracia, S. Jayadevan, J. Mol. Liq. 2016, 221, 930.
[53] V. K. Gupta, R. Kumar, A. Nayak, T. A. Saleh, M. A. Barakat,
[71] H. A. Oskooie, M. M. Heravi, N. M. Javadi, K. Bakhtiari, F. F.
Adv. Colloid Interface Sci. 2013, 193–194, 24.
Bamoharram, Synth. Commun. 2008, 38, 2864.
[54] H. Khani, M. K. Rofouei, P. Arab, V. K. Gupta, Z. Vafaei,
[72] J. Zhuo, Magn. Reson. Chem. 1997, 35, 311.
J. Hazard. Mater. 2010, 183, 402.
[73] C.‐L. Feng, N.‐N. Chu, S.‐G. Zhang, J. Cai, J.‐Q. Chen, H.‐Y.
Hu, M. Ji, Chem. Pap. 2014, 68, 1097.
[55] R. Saravanan, E. Sacari, F. Gracia, M. M. Khan, E. Mosquera,
V. K. Gupta, J. Mol. Liq. 2016, 221, 1029.
[74] Z. N. Siddiqui, K. Khan, N. Ahmed, Catal. Letters 2014, 144, 623.
[75] J. V. Greenhill, J. Chem. Soc., Perkin Trans. 1. 1976, 0, 2207.
[56] V. K. Gupta, R. Jain, A. Nayak, S. Agarwal, M. Shrivastava,
Mater. Sci. Eng. C 2011, 31, 1062.
[76] M. Salavati‐Niasari, G. Hosseinzadeh, F. Davar, J. Alloys
Compd. 2011, 509, 4098.
[57] T. A. Saleh, V. K. Gupta, J. Colloid Interface, Sci. 2012, 371, 101.
[58] K. Lamei, H. Eshghi, M. Bakavoli, S. Rostamnia, Catal. Letters
2017, 147, 491.
[77] S. K. Hussain, G. Nagaraju, E. Pavitra, G. S. R. Raju, J. S. Yu,
CrystEngComm 2015, 17, 9431.
[59] F. Panahi, S. K. Dangolani, A. Khalafi‐Nezhad, Chemistry Select
2016, 1, 3541.
[78] M. R. Mohammadizadeh, A. Hasaninejad, M. Bahramzadeh, Z.
S. Khanjarlou, Synth. Commun. 2009, 39, 1152.
[60] L. M. Rossi, M. A. S. Garcia, L. L. R. Vono, J. Braz. Chem. Soc.
2012, 23, 1959.
[79] S. Shendage, J. Nagarkar, Curr. Chem. Lett. 2013, 2, 145.
[61] R. B. N. Baig, M. N. Nadagouda, R. S. Varma, Coord. Chem.
Rev. 2015, 287, 137.
How to cite this article: Mousavi SR, Sereshti H,
Nodeh HR, Foroumadi A. A novel and reusable
magnetic nanocatalyst developed based on
graphene oxide incorporated strontium
nanoparticles for the facial synthesis of β‐enamino
ketones under solvent‐free conditions. Appl
Organometal Chem. 2018;e4644. https://doi.org/
10.1002/aoc.4644
[62] B. Karimi, F. Mansouri, H. M. Mirzaei, ChemCatChem 2015,
7, 1736.
[63] E. Tabrizian, A. Amoozadeh, RSC Adv. 2016, 6, 96606.
[64] B. Hemmati, S. Javanshir, Z. Dolatkhah, RSC Adv. 2016, 6, 50431.
[65] A. A. El‐Remaily, M. A. El, A. M. Abu‐Dief, R. M. El‐Khatib,
Appl. Organomet. Chem. 2016, 30, 1022.
[66] J. Pyun, Angew. Chemie Int. Ed. 2011, 50, 46.
[67] Y. Li, W. Gao, L. Ci, C. Wang, P. M. Ajayan, Carbon N. Y. 2010,
48, 1124.