CuI/Fe3O4 NPs@Biimidazole IL-KCC-1 as a leach proof nanocatalyst for the synthesis of imidazo[1,2-a]pyridines in aqueous medium

Article abstract of DOI:10.1002/aoc.6031

In the present work, an innovative leach proof nanocatalyst based on dendritic fibrous nanosilica (DFNS) modified with ionic liquid loaded Fe₃O₄ NPs and CuI salts was designed and applied for the rapid synthesis of imidazo[1,2-a]pyri

Full text of DOI:10.1002/aoc.6031

Received: 26 May 2020
DOI: 10.1002/aoc.6031
Revised: 18 August 2020
Accepted: 8 September 2020
F U L L P A P E R
CuI/Fe3O4 NPs@Biimidazole IL-KCC-1 as a leach proof
nanocatalyst for the synthesis of imidazo[1,2-a]pyridines in
aqueous medium
Sajjad Azizi1 | Nasrin Shadjou2
| Jafar Soleymani1
1Pharmaceutical Analysis Research
In the present work, an innovative leach proof nanocatalyst based on dendritic
fibrous nanosilica (DFNS) modified with ionic liquid loaded Fe3O4 NPs and
CuI salts was designed and applied for the rapid synthesis of imidazo[1,2-a]
pyridines from the reaction of phenyl acetylene, 2-aminopyridine,
and aldehydes in aqueous medium. The structure of the synthesized
nanocatalyst was studied by field emission scanning electron microscopy
(FESEM), transmission electron microscopy (TEM), Fourier transform infrared
(FT-IR), flame atomic absorption spectroscopy (FAAS), energy-dispersive
X-ray (EDX), and X-ray diffraction (XRD), vapor–liquid–solid (VLS), and
adsorption/desorption analysis (Brunauer–Emmett–Teller [BET] equation)
instrumental techniques. CuI/Fe3O4NPs@IL-KCC-1 with high surface area
(225 m2 g−1) and porous structure not only exhibited excellent catalytic activity
in aqueous media but also, with its good stability, simply recovered by an
external magnet and recycled for eight cycles without significant loss in its
intrinsic activity. Higher catalytic activity of CuI/Fe3O4NPs@IL-KCC-1 is due
to exceptional dendritic fibrous structure of KCC-1 and the ionic liquid groups
that perform as strong anchors to the loaded magnetic nanoparticles (MNPs)
and avoid leaching them from the pore of the nanocatalyst. Green reaction
media, shorter reaction times, higher yields (71–97%), easy workup, and no
need to use the chromatographic column are the advantages of the reported
synthetic method.
Center, Tabriz University of Medical
Sciences, Tabriz, Iran
2Nanotechnology Research Group,
Faculty of Science and Chemistry, Urmia
University, Urmia, Iran
Correspondence
Nasrin Shadjou, Nanotechnology
Research Group, Faculty of Science and
Chemistry, Urmia University, Urmia,
Iran.
Email: n.shadjou@urmia.ac.ir
K E Y W O R D S
advanced nanomaterials, dendritic fibrous nanosilica, imidazo[1,2-a]pyridines, magnetic
nanocatalyst
1 | INTRODUCTION
colleagues,[4,5] shows excellent activities in various
research areas such as catalysis and biomedical
Recently, porous silica materials due to its useful proper-
ties, such as high mechanical, thermal, and hydrothermal
stability, low toxicity and density, cost-effectiveness,
good biocompatibility, and easy of surface modification,
have received a lot of attention.[1–3] Dendritic fibrous
nanosilica (DFNS), introduced by Polshettiwar and
applications. KCC-1 with having dendritic fibrous
morphology is an exceptional nanomaterial, which is in
principle availability from totally sides in comparison
with other mesoporous material such as MCM-41 and
SBA-15 with tubular pores.[6] Hence, various
functional materials such as organic functional groups,
Appl Organomet Chem. 2020;e6031.
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© 2020 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.6031

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AZIZI ET AL.
organometallics, metal oxides, and some metal
nanoparticles can be loaded in the pores of the KCC-1
without the blocking of its channels or the pores, and
most importantly, accessibility of newly generated active
sites was increased. Whereas the surface area of KCC-1 is
lower than the MCM-41 and SBA-15, but the results
show that its openness is affectedly suitable than previous
conventional silica nanomaterials. Also, special morphol-
ogy and structure allow better diffusion and loading of
the agents and active sites in comparison with SBA-15
and MCM-41. Furthermore, DFNS with having thin silica
walls possesses better thermal and mechanical stability,
which is one of the serious concerns in conventional
mesoporous materials.
On the other hand, literature review exhibits that
loading of ionic liquids (ILs) on the structure of meso-
porous silica materials leads to increasing of their catalyt-
ically behavior. Based on their significant properties such
as high ionic conductivity, excellent thermal stability,
ecofriendly, stability, and wide liquid temperature range
window, ILs have been used for the organic synthesis.[7,8]
Various types of ILs that grafted to different supports not
only can be used as reaction media and catalysis but also
can be stabilized various nanoparticles because of their
coordination and electrostatic interactions with ions and
metal atoms.[9] Also, during the reaction procedure, the
supported ILs can provide appropriate hydrophobic
media and enhance the catalytic activity of the catalyst.
Therefore, ILs loaded nanocatalysts have been widely
used for the heterocyclic compound synthesis.[10]
Until now, different copper containing catalysts such
as Cu-MOFs, CuSO4/glucose, CuCl/Cu (OTf)2,
CuI/NaHSO4-SiO2, Cu-MnO, CuI/Cu (OTf)2, and
CuSO4/p-TsOH have been used for the efficient synthesis
of imidazo[1,2-a]pyridine.[23–29]
It is important to point out that iron oxide magnetic
nanoparticles (MNPs) have been predicted to be a prom-
ising immobilization matrix due to its fast electron-
transfer kinetics, robust adsorption capacity, high
surface-to-volume ratio, biocompatibility, and nontoxic
nature. Iron oxide MNPs can be proposed as suitable
microenvironment for increment of the organic reactions
kinetic based on their catalytically behavior.[30–40]
Following previous research work,[41] fibrous nano-
silica modified with IL loaded Fe3O4 NPs and CuI salts is
the best candidate as a magnetic nanocatalyst for the syn-
thesis of imidazo[1,2-a]pyridines in aqueous solution. In
the study, KCC-1 was functionalized with biimidazole.
Then Fe3O4 NPs and CuI salts were anchored to the
functionalized ILs. Finally, the new magnetic and green
nanocatalyst has been applied for the efficient synthesis
of imidazo[1,2-a]pyridine derivatives. Choosing this cata-
lyst and its higher catalytic activity is due to the excep-
tional dendritic fibrous morphology of KCC-1 and its
modification with the biimidazole IL functional groups
that perform as strong anchors to the loaded MNPs and
avoid leaching them from the pore of the nanocatalyst
(Scheme 2).
One of the most important kinds of fused heterocyclic
compounds with attractive biological and pharmacologi-
cal properties is imidazopyridines. Antibacterial,[11]
varicella-zoster,[12] antiviral,[13–15] anti-cancer,[16] and
antifungal[17,18] agents are the interesting properties of
2 | EXPERIMENTAL
2.1 | Materials
Tetraethyl orthosilicate (TEOS, 98%), (3-aminopropyl)
triethoxysilane (APTES, 99%), and malachite green were
purchased from Sigma-Aldrich Co, USA. The employed
solvents during synthesis procedures were obtained from
Merck, Germany. Some of the solvents used in the
these
compounds.
Zolpidem,[19,20]
Alpidem,[19]
Zolimidine,[21] and Olprinone[22] are some of the
synthetic drugs based on imidazo[1,2-a]pyridine frame-
work (Scheme 1).
SCHEME 1 Drugs structure with imidazo[1,2-a]pyridine
SCHEME 2 Synthesis of imidazo[1,2-a]pyridines in the
framework
presence of CuI/Fe3O4 NPs@IL-KCC-1 as a magnetic nanocatalyst

AZIZI ET AL.
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present
study
were
toluene,
hexanol,
and
dimethylformamide (DMF) were included in a 100-ml
round-bottomed flask and stirred for 60 min under nitro-
gen atmosphere at 60ꢀC. At the next step, the generated
methanol and DMF were separated by vacuum from
the reaction mixture. After that, dry DMF (20 ml) and
1-methyl-3-(oxiran-2-yl-methyl)-1H-imidazolium chloride
were added drop wisely into the reaction mixture and
stirred at 60ꢀC for 24 h. In the next step, the mixture was
filtered and then washed with DW three times and dried.
Finally, to replace the chloride ion with hydroxide ion in
the IL, the solid potassium hydroxide and the dried solid
from the previous step were added to the water (50 ml).
After striating the mixture at room temperature, over-
night the mixture was centrifuged and washed with aque-
ous and dried under reduced pressure. So IL-KCC-1 was
dimethylsulfoxide (DMSO). Cetyltrimethylammonium
bromide was also purchased from Merck, which was used
as surfactant during the preparation of KCC-1. Deionized
water in this study was produced in laboratory. No fur-
ther purification was performed on materials and
reagents, and they were used as purchased.
2.2 | Instrumentation
X-ray diffraction (XRD) was performed by Siemens D
5000 X-Ray diffractometer (Texas, USA). UV–Vis spectro-
photometer analysis was achieved by Shimadzu UV-1800
with a resolution of 1 nm. Transmission electron
microscopy (TEM) images were recorded by Carl Zeiss
LEO 906 electron microscope operated at 100 kV
(Oberkochen, Germany). Field emission scanning elec-
tron microscopy (FESEM) analysis was done by TESCAN
system of FEG-SEM MIRA3 TESCAN (Brno, Czech
Republic). Fourier transform infrared (FT-IR) spectra
were recorded by using Shimadzu model FT-IR Prestige
21 spectrophotometer (Tokyo, Japan). Brunauer–
Emmett–Teller (BET) was performed on a Micromeritics
NOVA 2000 (Florida, USA).
synthesized. Then
a
blend of FeCl2Á4H2O (1 g),
FeCl3Á6H2O (2.5 g), along with IL-KCC-1 (1.0 g), and
aqueous ammonia was included to a 50-ml deionized
water and stirred vigorously for 60 min at 80ꢀC in
pH = 12. Using this method, Fe3O4 NPs were doped on
the substrate of IL-KCC-1, and the Fe3O4 NPs@IL-KCC-1
was produced.
2.5 | Synthesis of the CuI/Fe3O4
NPs@IL-KCC-1
2.3 | General procedure for the synthesis
of imidazo[1,2-a]pyridine derivatives
The obtained precipitate in the previous step was sepa-
rated using external magnet, washed by DW, and dried at
60ꢀC for 6 h. In the next step, dried precipitate (1 g,
Fe3O4 NPs@IL-KCC-1) was included to the solution of
CuI (0.190 g in 50-ml methanol) and stirred at 30ꢀC for
24 h. Then the obtained magnetic nanocatalyst was sepa-
rated using external magnet, washed with acetone, etha-
nol, and DW, and dried in air. The schematic of the
synthesized nanocatalyst is shown in Scheme 3.
A
mixture of benzaldehyde (1 mmol) and
2-aminopyridine (1 mmol) was added in a 25.0-cc round-
bottomed flask and stirred for 20 min at room tempera-
ture. Then phenyl acetylene (1.1 mmol), (CuI/Fe3O4
NPs@IL-KCC-1) (0.034 mol %), CTAB (5 mg), and H2O
(4.0 ml) were included to the above solution and stir for
specific period of time under reflux conditions. Thin-layer
chromatography (TLC) was used for the monitoring of
reaction process till completion. The catalyst was sepa-
rated by an external magnet and washed several times
with water and acetone to use in subsequent reactions.
Then the obtained product was crystallized by ethanol to
the further purification.
3 | RESULTS AND DISCUSSIONS
3.1 | Characterization of the nanocatalyst
After synthesis and modification of the magnetic
nanocatalyst, the morphology and structure of
CuI/Fe3O4NPs@IL-KCC-1 were investigated by SEM,
TEM, FT-IR, flame atomic absorption spectroscopy
(FAAS), energy-dispersive X-ray (EDX), XRD, BET, and
BJH analyses, and vapor–liquid–solid (VLS) methods.
The amount of copper and iron that loaded on the
fibrous dendritic silica was measured using FAAS,
which the amount of iron and copper loaded in
the CuI/Fe3O4NPs@IL-KCC-1 catalyst was 5.91 and
22.54 wt%, respectively.
2.4 | Synthesis of the Fe3O4
NPs@IL-KCC-1
After synthesis of DFNS (KCC-1) according to our previ-
ous report,[41,42] it is modified by 1-methyl-3-(oxiran-
2-ylmethyl)-1H-imidazol-3-ium chloride to generate a
new functionalized nanocatalyst. For this purpose,
KCC-1 (1 g), sodium methoxide (3.0 g), and 20 ml of

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AZIZI ET AL.
SCHEME 3 Preparation of the
CuI/Fe3O4NPs@IL-KCC-1 nanocatalyst
FIGURE 1 Fourier transform
infrared spectra of the prepared
CuI/Fe3O4 NPs@IL-KCC-1 nanocatalyst
In the FT-IR spectrum (Figure 1), the peaks related to
3426 cm−1 is assigned to O–H bonds of engineered mag-
netic nanocatalyst.
Furthermore, the FESEM and TEM analyses were
applied for the study of the morphology and the structure
the stretching vibrations of C C and C N in the
imidazolium rings appear in 1428 and 1628 cm−1, respec-
tively. The peak at 593 cm−1 belongs to the vibration of
Fe–O in Fe3O4. Also, the weak peak at 670 cm−1 can be
attributed to copper iodide bond, and the sharp peak at
of
the
synthesized
CuI/Fe3O4
NPs@IL-KCC-1
nanocatalyst (Figure 2). Fibrous morphology and

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FIGURE 2 Field emission scanning electron microscopy
(a) and transmission electron microscopy (b) images of the
CuI/Fe3O4 NPs@IL-KCC-1 in different magnification

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AZIZI ET AL.
uniform spheres of KCC-1 were approved by these
imaging methods.
(1 mmol), and phenyl acetylene (1.1 mmol) under reflux
conditions was selected as a model reaction (Scheme 4).
At first, the model reaction was investigated in the
presence of different amounts of CuI/Fe3O4 NPs@IL-
KCC-1 as a nanocatalyst in EtOH under reflux condi-
tion. Obtained results are shown in Table 2. It was
observed that no product was obtained without catalyst
after 180 min (Table 2, entry 1). In continuation, by
adding and increasing the amount of the catalyst from
0.003 to 0.034 mol %, the yield of the reaction was
increased (Table 2, entries 2–6). But with an increase in
the amount of catalyst more than 0.034 mol %, the effi-
ciency of the reaction was not changed. Hence,
0.034 mol % of the catalyst was selected as an opti-
mized amount of nanocatalyst for the reaction (Table 2,
entries 7–9).
Based on TEM images, dendritic structure of
CuI/Fe3O4 NPs@IL-KCC-1 is obvious. Also, average size
of particle was obtained as 30 nm. Interestingly, spongy
morphology of the synthesized nanocomposite is
noticeable. It is important to point out that ILs lead to
cross-link of whole nanomaterial, which lead to strong
interaction. In addition, using TEM images, existence of
MNPs on the structure of nanocatalyst was approved.
To demonstrate the coated Fe3O4 and CuI in the
CuI/Fe3O4NPs@IL-KCC-1 nanocatalyst structure, EDX
was utilized (Figure 3a). The EDX analysis proved the
presence of O, Si, C, N, and Cu characteristic peaks. Also,
all of these results were confirmed by map analysis
(Figure 3b).
In the next step, to evaluate the crystal structure of
the CuI/Fe3O4 NPs@IL-KCC-1 nanocatalyst, XRD anal-
ysis was applied (Figure 4). Results show that the peaks
at 2θ = 12.46ꢀ, 25.20ꢀ, 29.33ꢀ, 42.01ꢀ, 49.85ꢀ, 52.60ꢀ,
61.76ꢀ, 67.24ꢀ, 69.30ꢀ, 77.49ꢀ, 79.30ꢀ, and 89.21ꢀ for
cubic CuI and peaks at 30.39ꢀ, 35.24ꢀ, 43.53ꢀ, 54.14ꢀ,
58.09ꢀ, and 63.08ꢀ for cubic Fe3O4. Also, a wide peak in
the range of 2θ = 19–30ꢀ is related to the amorphous
silica (Figure 4).
The porous nature of CuI/Fe3O4NPs@IL-KCC-1 and
bare KCC-1-NH2 was evaluated by BET and BJH analyses
(Figure 5). Using these methods, porosity and surface
area of the nanocatalyst were measured. In addition,
using BJH analysis, the pore volume of the CuI/Fe3O4
NPs@IL-KCC-1 and KCC-1 was calculated and summa-
rized in Table 1. According to these data, the pore vol-
umes altered from 1.52 in 0.77 cm3 g−1 for KCC-1 (bare
material) and CuI/Fe3O4 NPs@IL-KCC-1. Also, surface
area was obtained as 225 and 617 m2 g−1 for CuI/Fe3O4
NPs@IL-KCC-1 and bare materials (KCC-1), respectively.
Also, the mean pore diameter of CuI/Fe3O4 NPs@IL-
KCC-1 and KCC-1 was obtained as 13.76 and 9.9 nm,
respectively.
As the table results show, when the model reaction is
done in the absence of catalyst in water under reflux and
solvent-free conditions, no desired product obtains after
30 h (Table 3, entries 1–3). In the following, to show the
impact of new magnetic nanocatalyst (CuI/Fe3O4
NPs@IL-KCC-1), the model reaction was investigated in
the existence of the CTAB (in solvent-free conditions and
in the presence of H2O as solvent) and Fe3O4 NPs. No
product was formed in the presence of these catalysts,
and in the presence of CuI as a catalyst, the yield of the
reaction was only 10% after 30 h (Table 3, entries 2–5).
As can be seen in Table 3, different solvents like
water, ethanol, methanol, acetonitrile, and also solvent-
free conditions, in the presence of CuI/Fe3O4 NPs@IL-
KCC-1 (0.034 mol %), were used as a solvent for the
model reaction (Table 3, entries 7–10). In these condi-
tions, the yields of the reaction in 4 h were 86%, 60%,
45%, and 40%, respectively. Hence, the highest yield of
the product is obtained in the presence of 0.034 mol % of
CuI/Fe3O4 NPs@IL-KCC-1 in water, compared with
other solvents. Hence, water was selected as an optimum
solvent. Therefore, all of the reactions were performed in
aqueous solution.
The VLS magnetization curve of prepared
nanocatalyst is shown in Figure 6, which exposed the
super-paramagnetic properties of the prepared
nanocatalyst. The saturation magnetization CuI/Fe3O4
Also, the obtained results show that when the
solvent-free conditions were considered for the reaction
in the presence and the absence of CTAB and CuI/Fe3O4
NPs@IL-KCC-1 as a catalyst, the yields of the reaction
were 80% and 76%, respectively. As the results show, the
yield of the reaction decreases in these conditions in com-
parison with aqueous media (Table 3, entries 10 and 11).
It is necessary to mention that, for the increasing of
the solubility of the reactants and the reaction kinetic in
the aqueous media, CTAB as a cationic surfactant has
been used. It should be noted that in the presence of sur-
factant and with increasing the time till 6 h, the yield of
the reaction did not change (Table 3, entries 12 and 13).
It should be noted that when the reaction is done at room
NPs@IL-KCC-1 nanocatalyst is 22.47 emu g−1
.
3.2 | Application of CuI/Fe3O4 NPs@IL-
KCC-1 nanocatalyst for the synthesis of
imidazo[1,2-a]pyridines derivatives
At first, to find the optimum reaction conditions for the
synthesis of imidazo[1,2-a]pyridines derivatives, a mixture
of 4-chloro benzaldehyde (1 mmol), 2-aminopyridine

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FIGURE 3 Energy-dispersive X-ray
(a) and map analysis (b) of CuI/Fe3O4
NPs@IL-KCC-1

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FIGURE 4 X-ray diffraction pattern of
CuI/Fe3O4 NPs@IL-KCC-1 nanocatalyst
FIGURE 5 Nitrogen adsorption/desorption
and BJH of prepared nanocatalyst. BET,
Brunauer–Emmett–Teller
TABLE 1 Porosity evaluation of CuI/Fe3O4 NPs@IL-KCC-1 and its comparison with KCC-1 as bare material
Material type
KCC-1
Pore size (nm)[a]
Pore volume (cm3 g−1 [b]
)
Surface area (m2 g−1
)
9.9
1.5
617
225
CuI/Fe3O4 NPs@IL-KCC-1
13.76
0.77
aPore size was calculated by Brunauer–Emmett–Teller method.
bPore volume determined from nitrogen physicosorption isotherm.

AZIZI ET AL.
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number (TON) was obtained as 2941 after optimization
of nanocatalyst.
In order to evaluate the applicability of CuI/Fe3O4
NPs@IL-KCC-1 as advanced nanocatalyst, various
types of aromatic aldehydes were used to react with phe-
nyl acetylene and 2-aminopyridine under reflux condi-
tions, and obtained results are summarized in Table 4.
The obtained results show that the aromatic aldehydes
with withdrawing groups (Cl, Br, CN, F, CF3) have better
yields and shorter reaction time in comparison with alde-
hydes with electron donation groups (Me, OMe).
Based on the obtained results, the proposed mecha-
nism for the synthesis of imidazo[1,2-a]pyridines in the
presence of CuI@Fe3O4 NPs-IL-KCC-1 is shown in
Scheme 5. As can be seen, in the presence of nanocatalyst
with IL that loaded Fe3O4 NPs and CuI salts, the imine
as an intermediate (i) was formed. In the next step, the
phenyl acetylene is converted to phenyl acetylene
copper(I), and the intermediate (ii) is formed in the pres-
ence of magnetic nanocatalyst, which by its attacking to
the imine bond, intermediate (iii) is produced. Finally,
by cyclization of the mentioned intermediate, the major
product was obtained with high yields.
FIGURE 6 Magnetic hysteresis as a function of field of
CuI/Fe3O4 NPs@IL-KCC-1
SCHEME 4 The model reaction to optimize the reaction
condition
3.3 | Reusability of the catalyst
temperature, the efficiency of the reaction decreases
(Table 3, entry 14).
For industrial applications, the reusability of
nanocatalysts is so essential. Hence, the recyclability of
the nanocatalyst was evaluated for the one-pot synthesis
of imidazo[1,2-a]pyridines, using the reaction of aromatic
benzaldehydes, 2-aminopyridine, and phenyl acetylene in
aqueous solution. In this method, external magnet was
used for easy removal of the CuI@Fe3O4 NPs-IL-KCC-1
from the reaction mixture and then washed with water
and acetone. So the separated nanocatalyst was air dried
carefully before being used in subsequent runs. As can be
The results of Table 4 obviously show that CuI/Fe3O4
NPs@IL-KCC-1 (0.034 mol %) is an effective nanocatalyst
for the reaction of the 4-chloro benzaldehyde (1 mmol),
2-aminopyridine (1 mmol), phenyl acetylene (1.1 mmol),
and CTAB (5 mg) in water (4.0 ml), under reflux condi-
tions to generate imidazo[1,2-a]pyridines derivatives
(Table 4, 4a–m) in great yields. Finally, the products
were obtained by an easy workup process. Also, turnover
TABLE 2 Optimization of the
amount of the catalyst for the model
Amount of the
catalyst (mol %)
Entry
Yield (%)
Time (min)
180
reaction
1
0
0
2
3
4
5
6
7
8
9
0.003
0.006
0.013
0.027
0.034
0.04
19
46
64
85
96
96
96
96
180
180
180
180
180
180
0.047
0.054
180
180

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AZIZI ET AL.
TABLE 3 Optimization of the reaction conditions
Entry
Catalyst
Surfactant
Solvent
H2O
-
Reaction condition
Reflux
Time (h)
Yield (%)
NR
NR
NR
NR
10
1
-
-
30
30
30
30
30
4
2
-
CTAB
CTAB
CTAB
CTAB
-
Solvent free
Reflux
3
-
H2O
H2O
H2O
H2O
EtOH
MeOH
CH3CN
-
4
Fe3O4
Reflux
5
CuI
Reflux
6
CuI/Fe3O4 NPs@IL-KCC-1
CuI/Fe3O4 NPs@IL-KCC-1
CuI/Fe3O4 NPs@IL-KCC-1
CuI/Fe3O4 NPs@IL-KCC-1
CuI/Fe3O4 NPs@IL-KCC-1
CuI/Fe3O4 NPs@IL-KCC-1
CuI/Fe3O4 NPs@IL-KCC-1
CuI/Fe3O4 NPs@IL-KCC-1
CuI/Fe3O4 NPs@IL-KCC-1
Reflux
86
7
-
Reflux
4
60
8
-
Reflux
4
45
9
-
Reflux
4
40
10
11
12
13
14
-
Solvent free
Solvent free
Reflux
4
76
CTAB
CTAB
CTAB
CTAB
-
4
80
H2O
H2O
H2O
3
88
Reflux
6
88
Room temperature
4
60
Abbreviation: NR, not reported.
TABLE 4 Comparison of the time and yield of imidazo[1,2-a]pyridines derivatives synthesis in the presence of CuI/Fe3O4 NPs@IL-
KCC-1
Entry
4a
Product
Time (h)
Yield[a] (%)
M.P.
3
90
117–119[25]
4b
4c
3
3
88
87
144–145[32]
161–163[43]
4d
4e
3
3
97
96
134–135[43]
81–83[26]

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TABLE 4 (Continued)
Entry
4f
Product
Time (h)
Yield[a] (%)
M.P.
140–142[43]
3
92
4g
3
90
117–118[44]
4h
4i
4
3
71
90
158–159[45]
131–133[44]
4j
3
4
3
86
72
90
155[25]
4k
4l
Semisolid[26]
117–118[45]
4m
3
85
140–141[46]
aIsolated yields.

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AZIZI ET AL.
seen in Figure 7, it was established that under mild reac-
tion conditions, this green nanocatalyst indicated recycla-
ble behavior eight times with minor reduction in its
catalytic activity.
4 | CONCLUSION
In summary, the results indicated that CuI/Fe3O4
NPs@IL-KCC-1 as
a
magnetic leaching free
nanocatalyst is an efficient and green nanoreactor for
the synthesis of imidazo[1,2-a]pyridines from the one-
pot reaction of 2-aminoprydine, phenyl acetylene, and
aromatic aldehydes in water under reflux conditions.
Exceptional catalytic behavior in aqueous media with
high surface area and porous structure, shorter reaction
times in comparison with previous reported methods,
excellent yields, easy workup, no use of chromato-
graphic columns and toxic solvents, and magnetically
recoverable of the nanocatalyst are advantages of
this work.
SCHEME 5 Proposed mechanism for the synthesis of imidazo
[1,2-a]pyridines in the presence of CuI@Fe3O4 NPs-IL-KCC-1
FIGURE 7 Effective separation of
nanocatalyst (CuI/Fe3O4 NPs@IL-KCC-1) from
the reaction mixture by means of external
magnet and showing its reusability

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DATA AVAILABILITY STATEMENT
The data that support the findings of this study are avail-
able from the corresponding author upon reasonable
request.
AUTHOR CONTRIBUTIONS
Sajjad Azizi: Formal analysis. Nasrin Shadjou: Concep-
tualization; methodology. Jafar Soleymani: Investiga-
tion; methodology.
ORCID
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How to cite this article: Azizi S, Shadjou N,
Soleymani J. CuI/Fe3O4 NPs@Biimidazole
IL-KCC-1 as a leach proof nanocatalyst for the
synthesis of imidazo[1,2-a]pyridines in aqueous
medium. Appl Organomet Chem. 2020;e6031.
https://doi.org/10.1002/aoc.6031