Fe3O4?SiO2?(CH2)3-urea-quinoline sulfonic acid chloride: A novel catalyst for the synthesis of coumarin containing 1,4 dihydropyridines

Article abstract of DOI:10.1016/j.molstruc.2020.129294

Fe₃O₄?SiO₂?(CH₂)₃-urea-quinoline sulfonic acid chloride, as a novel and efficient nanomagnetic catalyst bearing urea linkers, was designed, synthesized and then fully characterized by using various te

Full text of DOI:10.1016/j.molstruc.2020.129294

Journal of Molecular Structure 1224 (2020) 129294
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstr
Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride: A novel
catalyst for the synthesis of coumarin containing 1,4 dihydropyridines
Haniyeh Saffarian, Fatemeh Karimi, Meysam Yarie∗, Mohammad Ali Zolfigol∗
Department of Organic Chemistry, Faculty of Chemistry, Bu-Ali Sina University, Hamedan, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride, as a novel and efficient nanomagnetic cata-
lyst bearing urea linkers, was designed, synthesized and then fully characterized by using various tech-
niques. To investigate the catalytic activity of the described catalyst, it was used for the synthesis of
coumarin containing 1,4-dihydropyridines (DHPs), through a condensation reaction of aromatic aldehy-
des, 4-hydroxycoumarin, and ammonium acetate under solvent-free conditions. This procedure includes
important aspects like simple procedure, simplicity of product isolation using water, decreasing the tem-
perature of reaction, disuse of solvent, high to excellent yields, environmentally benign reaction condi-
tions and short reaction times. Also, the presented catalyst was recycled and reused for at least five times
with only a negligible decrease in its catalytic activity. The applied catalyst has both acidic and H-bond
donor-acceptor sites so that it can use as a dual role catalytic system.
Received 3 September 2020
Accepted 17 September 2020
Available online 18 September 2020
Keywords:
Anomeric based oxidation
Coumarin containing 1,4-dihydropyridines
1,4-Dihydropyridines
Multi-component reaction
Nanomagnetic catalyst
Urea
© 2020 Elsevier B.V. All rights reserved.
1. Introduction
tion of solvents. So, the development of simple, efficient and eco-
friendly methods for the preparation of 1, 4-dihydropyridines un-
Over the years, among the heterocyclic compounds containing
the oxygen atoms, coumarin derivatives due to their diverse phar-
macological and biological properties, have attracted main atten-
tions [1]. These compounds display a broad range of biological
activities including anticancer [2], anti-HIV [3], anti-tuberculosis
[4], anti-influenza [5], anti-Alzheimer [6], antioxidant [7], antico-
agulant [8], antibacterial [9], anti-dyslipidemic [10], antimicrobial
[11] and anti-inflammatory activity [12].
der green conditions are desirable. Chemical structure of some nat-
ural products and synthetic drugs bearing DHP core are presented
in Scheme 1.
From the perspective of green chemistry, high activity of cata-
lysts and their reusability are two important factors in the most of
modern catalytic processes. In this respect, magnetic nanoparticles
(MNPs) have been emerged as one of the most useful heteroge-
neous catalysts due to their numerous applications in the chemical
processes as well as organic synthesis. They are robust, inexpensive
and recyclable by an external magnet for several runs without con-
siderable loss of their selectivity and activity [22,23]. Good biocom-
patibility and biodegradability, as well as basic magnetic character-
istics could be denoted for functional organic materials grafted to
MNPs [24,25].
Polycyclic 1,4-dihydropyridines (1,4-DHPs) are an important
class of heterocyclic compounds containing nitrogen atoms with
intriguing molecular structures. They have been showed remark-
able pharmacological activities. Some of the 1,4-dihydropyridines
have been emerged as opening potassium channels [13], blocking
calcium channel [14], anticonvulsant, analgesic, anti-inflammatory
[15], treating Alzheimer’s disease [16], anti-tumor [17], antimi-
crobial [18] and antimalarial [19] agents. Although, various pro-
cedures are reported for the synthesis of fused dihydropyridines
[20,21], most of these methodologies have disadvantages such as
use of microwave irradiation, utilization of costly and environmen-
tally poisonous catalysts, long reaction times, low yields of the
products, tedious workup protocols, high temperature and utiliza-
The compounds with urea moiety are interesting structures
with biological properties which presented in numerous fields such
as resin precursors, agriculture industry, dyes, pharmaceutical in-
gredients and additives to petroleum compounds and polymers
[26]. In addition to, they were utilized as acidic and basic cata-
lysts, chiral acid catalysts, coupling with metals as catalyst, cou-
pling with ionic liquids, urea anions catalysts, urea polymer cat-
alysts and urea based supported catalysts. Recently, we have re-
viewed the performance of biological urea based catalysts in the
chemical reactions [27].
∗
Corresponding authors.
With regard to green chemistry, the construction of com-
plex functionalized molecules through multi-component reactions
E-mail addresses: myari.5266@gmail.com (M. Yarie), zolfi@basu.ac.ir (M.A.
Zolfigol).
https://doi.org/10.1016/j.molstruc.2020.129294
0022-2860/© 2020 Elsevier B.V. All rights reserved.

H. Saffarian, F. Karimi, M. Yarie et al.
Journal of Molecular Structure 1224 (2020) 129294
Scheme 1. Some natural products and synthetic drugs bearing DHP moieties.
Scheme 2. Synthesis of Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride.
(MCRs) become increasingly important to both pharmaceuticals
and organic chemists due to their merit features such as higher
atom economy, convenient reaction design, simplicity of operation
and purification, and minimization of costs, time, energy, solvents,
and waste production compared to classical multi-step synthesis.
MCRs lead to interesting heterocyclic building blocks by the in-
troduction of several diversity elements in a single chemical event
[28,29].
nanomagnetic catalyst namely Fe3O4@SiO2@(CH2)3-urea-quinoline
sulfonic acid chloride and it’s catalytic application in one pot syn-
thesis of coumarin with 1,4-DHPs moieties (Schemes 2 and 3).
2. Experimental
2.1. General procedure for the synthesis of urea-based ligand
In continuation of our two decades studies on the chemistry
of 1,4-DHPs [30,31] and efforts to develop catalysts bearing urea
moiety [27,32], this exploration describes the preparation of novel
At first, urea-based ligand was prepared by the reaction
of triethoxy(3-isocyanatopropyl)silane (5 mmol, 1.237 g) and 8-
aminoquinoline (5 mmol, 0.720 g) under solvent free conditions at
2

H. Saffarian, F. Karimi, M. Yarie et al.
Journal of Molecular Structure 1224 (2020) 129294
Scheme 3. Catalytic synthesis of coumarin containing 1,4-DHPs.
60 °C for 4 h. Afterwards, the obtained product washed with the
mixture of n-hexane and dichloromethane (3 × 10 mL) to afford
the desired urea-based ligand (Scheme 2).
(q, 6H, J = 6 Hz, CH2O), 3.17(q, 2H, J = 6 Hz, CH2N, 1.56 (quint,
2H, J = 6 Hz, CH2), 1.15 (t, 9H, J = 6 Hz, CH3), 0.61- 0.66 (m, 2H,
CH2Si).
13C NMR (76 MHz, DMSO, δ, ppm): 155.6, 148.3, 138.1, 137.2,
136.9, 128.4, 127.6, 122.1, 119.2, 114.3, 58.2, 42.3, 23.7, 18.6, 7.8.
2.2. General procedure for the synthesis of
Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid
ꢀ
ꢀ
2.4.2. 7-p-Tolyldichromeno[4,3-b:3 ,4 -e]pyridine-6,8(7H,14H)–
dione (1i)
Initially, Fe3O4 nano particles were prepared on the basis
of the previously reported procedure [33]. In the next step,
Fe3O4@SiO2, was prepared through the reaction of Fe3O4 nano par-
ticles with tetraethyl orthosilicate (TEOS). Afterwards, the obtained
Fe3O4@SiO2 (1 g) was functionalized by the reaction with urea-
based ligand (2 mmol, 0.782 g) under refluxing toluene for 48 h.
In the next step, the obtained Fe3O4@SiO2@(CH2)3-urea- quinoline
(1 g), at ice bath subjected to the reaction with chlorosulfuric acid
(2 mmol, 0.233 g) in dichloromethane as solvent for 2 h. In the
final step, the Fe3O4@SiO2@(CH2)3-urea- quinoline sulfonic acid
chloride was washed thoroughly (dichloromethane (3 × 15 mL))
and air dried (Scheme 2).
Cream solid, M.p.: 256–258 °C.
FT-IR (KBr, ν, cm−1): 3377, 3183, 1675, 1618, 1534, 1407, 757.
1H NMR (301 MHz, DMSO, δ, ppm): 9.55 (br, 1H, NH), 7.95- 7.07
(m. 12 H, Aromatic), 6.39 (s, 1H, CH), 2.27 (s. 3H, Me).
13C NMR (76 MHz, DMSO, δ, ppm): 165.4, 152.6, 136.9, 135.0,
132.5, 129.2, 127.1, 124.4, 118.2, 116.5, 104.81, 36.1, 21.1.
ꢀ
ꢀ
2.4.3. 7-(4-Methoxyphenyl)dichromeno[4,3-b:3 ,4 -e]
pyridine-6,8(7H,14H)–dione (1j)
Cream solid, M.p.: 230–232 °C.
FT-IR (KBr, ν, cm−1): 3216, 3069, 2930, 1662, 1604, 1509, 758.
1H NMR (301 MHz, DMSO, δ, ppm): 7.91- 6.81 (m, 13 H, Aro-
matic, NH), 6.30 (s, 1H, CH), 3.72 (s, 3H, OMe).
13C NMR (76 MHz, DMSO, δ, ppm): 166.0, 165.2, 157.7, 152.7,
132.2, 128.2, 124.4, 124.1, 118.7, 116.3, 113.9, 104.8, 55.4, 35.8.
2.3. General procedure for the synthesis of coumarin containing
1,4-DHPs catalyzed by Fe3O4@SiO2@(CH2)3-urea- quinoline sulfonic
acid chloride
A round-bottomed flask was charged with arylaldehyde deriva-
tives (0.5 mmol), 4-hydroxycoumarin (0.162 g, 1 mmol), NH4OAc
(0.154 g, 2 mmol), and Fe3O4@SiO2@(CH2)3-urea- quinoline sul-
fonic acid chloride (10 mg) were stirred vigorously at 80 °C under
solvent free conditions for appropriate times (Table 2). Reaction
progress was monitored by TLC (using n-hexane and ethyl acetate
as eluent). After the reaction completion, hot ethanol was added
to the mixture. The catalyst was insoluble in hot ethanol and eas-
ily separated by an external magnet bar. After evaporation of sol-
vent, the precipitate was collected, filtered and washed with water
to afford the pure product 1a–q with the range of yields from 80
to 90%.
ꢀ
ꢀ
2.4.4. 7-(3,4-Dimethoxyphenyl)dichromeno[4,3-b:3 ,4 -e]
pyridine-6,8(7H,14H)–dione (1k)
Cream solid, M.p.: 264–266 °C.
FT-IR (KBr, ν, cm−1): 3417, 3207, 3078, 2995, 1651, 1613, 1533,
1405, 754.
1H NMR (301 MHz, DMSO, δ, ppm): 7.9- 6.7 (m, 12 H, Aromatic,
NH), 6.3 (s, 1H, CH), 3.7 (s, 3H, OMe), 3.6 (s, 3H, OMe).
13C NMR (76 MHz, DMSO,):165.9, 165.2, 152.7, 149.0, 147.6,
133.0, 132.2, 124.4, 124.1, 119.4, 118.6, 116.38, 112.2, 111.9, 104.8,
56.1, 56.0, 36.2.
2.4. Selected spectral data
2.4.5. 7-(2-Hydroxy-3-methoxyphenyl)
ꢀ
ꢀ
dichromeno[4,3-b:3 ,4 -e]pyridine-6,8(7H,14H)–dione (1l)
2.4.1. 1-(Quinolin-8-yl)−3-(3-(triethoxysilyl)propyl)urea (Urea-based
ligand)
Cream solid, M.p.: 209–211 °C.
FT-IR (KBr, ν, cm−1): 3393, 3073, 2982, 1665, 1616, 1566, 1513,
763.
Brown solid, M.p.: 121–123 °C.
FT-IR (KBr, ν, cm−1): 3298, 3273, 3093, 2974, 1693, 1642, 1558,
1518, 1103, 1079, 788.
1H NMR (301 MHz, DMSO, δ, ppm): 9.38 (s. 1H, NH), 8.86 (d,
1H, J = 3 Hz, Aromatic) 8.58 (d, 1H, J = 9 Hz, Aromatic), 8.32 (d,
1H, J = 9 Hz, Aromatic), 7.58- 7.43 (m, 4H, Aromatic, NH), 3.75
1H NMR (301 MHz, DMSO, δ, ppm): 7.91- 6.58 (m, 13 H, Aro-
matic, NH, OH), 6.25 (s, 1H, CH), 3.59 (s, 3H, OMe).
13C NMR (76 MHz, DMSO, δ, ppm): 166.4, 165.2, 152.7, 147.7,
145.0, 131.9, 124.4, 123.9, 119.7, 119.1, 116.2, 115.5, 112.2, 104.7,
56.2, 36.1.
3

H. Saffarian, F. Karimi, M. Yarie et al.
Journal of Molecular Structure 1224 (2020) 129294
Fig. 1. Comparative study of FT-IR spectra of Fe3O4 (a), Fe3O4@SiO2 (b), Fe3O4@SiO2@(CH2)3-urea-aminoquinoline (c) and Fe3O4@SiO2@(CH2)3-urea- aminoquinoline sulfonic
acid chloride (d), urea based ligand (e).
13000
O K
12000
11000
10000
9000
8000
7000
SiK
S K
6000
N K
5000
4000
3000
2000
1000
0
S K
C K
FeL
FeK
ClK
ClK
FeK
keV
10.00
0
Fig. 2. EDX analysis of the Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride.
3. Result and discussion
analysis. The outcomes of all applied analysis were discussed be-
low in details.
Arthur Rudolf Hantzsch had been reported the synthesis of 1,4-
DHPs in 1882. The chemistry of 1,4-DHPs comprehensively have
been reviewed [34]. Although this old one-pot multi-component
reaction (MCR) is a well-known name reaction in organic chem-
istry but the synthesis of new organic molecules which have 1,4-
DHPs moieties are a great demand due to their remarkable phar-
macological activities. On the basis of the mentioned facts, herein
we wish to report a new methodology for the synthesis coumarin
with 1,4-DHPs moieties.
In a comparative style, as shown in the Fig. 1, the FT-IR spectra
of different intermediates and desired catalyst were investigated
in the range 400–4000 cm−1. Addition of each layer to the previ-
ous one, leads to observation of characteristic peaks of new added
functional groups in the spectrum which proves the formation of
a new layer. The FT-IR spectrum of the final catalyst (d) shows all
predictable functional groups at their related positions. The broad
peak from about 2700–3700 cm−1 confirms the existence of acidic
OH and NH functional groups within the structure of the catalyst.
Also, amidic C = O (urea moiety) and S = O (sulfonic acid) func-
tional groups verified by their characteristic peaks at 1627 cm−1
and 1216 cm−1, respectively.
3.1. Characterization of the novel catalyst
In order to explore the elemental composition of the catalyst
Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride, energy-
dispersive spectroscopy (EDX) and elemental mapping analysis
were conducted (Figs. 2 and 3). The obtained data from these anal-
Firstly, characterization of Fe3O4@SiO2@(CH2)3-urea-quinoline
sulfonic acid chloride as a recoverable nanomagnetic catalyst was
performed using FT-IR, TGA, DTG, VSM, FESEM, Mapping and TEM
4

H. Saffarian, F. Karimi, M. Yarie et al.
Journal of Molecular Structure 1224 (2020) 129294
Fig. 3. Elemental mapping analysis of the Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride.
yses approve of each other well. Achieved data from both EDX and
elemental mapping (Figs. 2 and 3), approved the presence of Fe, O,
Si, C, N, S and Cl in the catalyst with a suitable dispersity.
weight loss from 180 to 520 °C can be ascribed to the decompo-
sition of organic layer connected to Fe3O4@SiO2 particles (weight
loss of about 35.3%). The mass residue above 600 °C can be at-
tributed to the inorganic parts of the catalyst including Fe3O4 or
Fe3O4@SiO2 particles. On the basis of the achieved results, the pre-
sented nanomagnetic catalyst well modified with active organic
parts and shows proper thermal behavior upon the investigated re-
action.
In attempting to investigate the surface morphological charac-
teristics and particle size of the prepared catalyst, SEM images
were recorded and are shown in the Fig. 4. The SEM images show
that the size of the catalyst particles is in the nano meter range
(10–15 nm) with sphere-like structure. These observations verified
with the achieved data from TEM images (Fig. 5).
As illustrated in Fig. 7, the magnetic behavior of Fe3O4@
SiO2@(CH2)3-urea-quinoline sulfonic acid chloride was also inves-
tigated using VSM and compared to that of Fe3O4@SiO2@(CH2)3-
urea-quinoline as intermediates in the synthetic pathway. As ex-
pected, decrease saturation magnetization from about 40 emu/g to
about 20 emu/g, is related to the new coated layer and confirmed
TGA/DTG analysis was applied to study the thermal stability of
Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride (Fig. 6).
The weight loss upon heating from room temperature to about
180 °C can be attributed to the evaporation of the solvents which
were employed during the course of catalyst preparation. Also, the
5

H. Saffarian, F. Karimi, M. Yarie et al.
Journal of Molecular Structure 1224 (2020) 129294
Fig. 4. SEM micrographs of the Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride.
Fig. 5. TEM images of the Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride.
the successful formation of desired catalyst. Also, this data verified
the capability of a simple external magnet for separation of the
catalyst from the reaction mixture.
At first, for achieving the optimal reaction parameters, the in-
fluence of temperature, catalyst loading and different solvents over
the reaction of 4-methyl benzaldehyde, 4-hydroxycoumarine, and
ammonium acetate as a model reaction, were investigated. On the
basis of our achieved experimental results, using 10 mg of the
Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride at 80 °C
under solvent free conditions supplied the best results. Elevating
the operational reaction temperature and increasing the amount of
catalyst did not lead to more favorable results. All obtained data
are summarized in Table 1.
3.2. Catalytic application of Fe3O4@SiO2@(CH2)3-urea-quinoline
sulfonic acid chloride for the synthesis of coumarin containing DHPs
After preparation and full characterization of the novel
Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride, its cat-
alytic activation was also investigated over a multi component
reaction between arylaldehydes, 4-hydroxycoumarins and ammo-
nium acetate to produce pyridine derivatives (2a-q) as favorite
products. Due to these compounds could be a puzzle piece of our
research interest in expanding of our new established term en-
titled “cooperative vinylogous anomeric based oxidation mecha-
nism” [35,36]. In contrast of our expected product, the obtained
spectral data showed that the reaction proceed towards the syn-
thesis of dihydropyridine derivatives (1a-q) (Scheme 4). Since these
compounds show remarkable pharmacological activities, we deter-
mine to complete the study and present an efficient method for
their synthesis.
Also, we performed the model reaction in the presence of re-
lated intermediates of the Fe3O4@SiO2@(CH2)3-urea-quinoline sul-
fonic acid chloride at 80 °C under solvent free conditions for
20 min. The achieved data as inserted in Table 2 shows no sat-
isfactory results compare with Fe3O4@SiO2@(CH2)3-urea-quinoline
sulfonic acid chloride.
Afterwards, scope and generality of the presented method was
investigated by examining the reaction of structurally diverse aro-
matic aldehydes, 4-hydroxycoumarin and ammonium acetate in
the presence a catalytic amount of described nanomagnetic cat-
6

H. Saffarian, F. Karimi, M. Yarie et al.
Journal of Molecular Structure 1224 (2020) 129294
Fig. 6. TGA and DTG analysis curves of the Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride.
60
40
20
0
c
d
-15000
-10000
-5000
0
5000
10000
15000
-20
-40
-60
Fig. 7. VSM curves of (c) Fe3O4@SiO2@(CH2)3-urea-quinoline and (d) Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride.
Scheme 4. Synthesis of coumarin containing DHPs in the presence of Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride.
7

H. Saffarian, F. Karimi, M. Yarie et al.
Journal of Molecular Structure 1224 (2020) 129294
Table 1
Optimization of reaction conditions upon the synthesis of molecule 1i in the presence of Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride as a novel
catalysta
.
Entry
Solvent
Temperature ( °C)
Catalyst (mg)
Time (min.)
Yield (%)b
1
2c
–
90
–
90
30
20
20
20
20
30
30
45
90
90
90
30
–
90
5
80
3
–
90
10
15
10
10
10
10
10
10
10
10
86
4
–
90
85
5
–
100
81
6
–
80
85
7
–
60
70
8
H2O
Reflux
Reflux
Reflux
Reflux
Reflux
85
9
EtOH
EtOAc
CH2Cl2
n-Hexane
75
10
11
12
20
Trace
Trace
a
Reaction conditions: 4-Methylbenzaldehyde (0.5 mmol, 0.06 g), 4-hydroxycoumarine (1 mmol, 0.162 g) and ammonium acetate (2 mmol, 0.154 g).
Isolated yields.
b
Table 2
Screening the model reaction in the presence of desired catalyst and its related inter-
mediatesa.
Entry
Catalyst
Yield (%)b
1
2
3
4
Fe3O4
40
40
65
85
Fe3O4@SiO2
Fe3O4@SiO2@(CH2)3-urea-quinoline
Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride
a
Reaction conditions: 4-Methylbenzaldehyde (0.5 mmol, 0.06 g), 4-
hydroxycoumarine (1 mmol, 0.162 g) and ammonium acetate (2 mmol, 0.154 g),
catalyst: 10 mg.
b
Isolated yields.
Fig. 8. Successful reusing test of Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride at the synthesis of target molecules 1i.
8

H. Saffarian, F. Karimi, M. Yarie et al.
Journal of Molecular Structure 1224 (2020) 129294
Table 3
Catalytic Synthesis of target molecules 1a-q in the presence of Fe3O4@SiO2@(CH2)3- urea-quinoline sulfonic acid chloridea.
alyst at the optimized reaction conditions. The obtained results
were illustrated in Table 3. All desired molecules were furnished
in short reaction times with high to excellent yields.
molecule 1i using condensation of 4-methyl benzaldehyde, 4-
hydroxycoumarine, and ammonium acetate under optimal condi-
tions for 20 min. After completion of each run, hot EtOH was
added to the reaction mixture. The desired product and unreacted
starting materials dissolve in hot EtOH, but the nanomagnetic cata-
lyst is not soluble, thus it can be separated from the reaction mix-
ture using an external magnet. Then, the recovered catalyst washed
well with ethanol, dried and then applied for next runs. As il-
lustrated in Fig. 8, the reusing test of Fe3O4@SiO2@(CH2)3-urea-
3–3. Recycling of Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid
chloride
In order to examine the green and economic aspects of
Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride, we also
explored reusability of prepared catalyst in the synthesis of
9

H. Saffarian, F. Karimi, M. Yarie et al.
Journal of Molecular Structure 1224 (2020) 129294
Scheme 5. A reasonable mechanistic pathway for the synthesis of molecule 1a.
quinoline sulfonic acid chloride was successful over five continuous
runs with only a marginal decreasing of its catalytic activity.
tion and recyclability of catalyst are the most attractive features of
presented protocol.
Also, we suggested
the synthesis of target molecule 1a in the presence of
Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride
a plausible mechanistic pathway for
Declaration of Competing Interest
The authors declare that they have no known competing finan-
cial interests or personal relationships that could have appeared to
influence the work reported in this paper.
(Scheme 5). At first, benzaldehyde is activated with nanomag-
netic catalyst and attacked by one molecule of 4-hydroxycoumarin
to obtained intermediate A and releasing one molecule of H2O.
Second molecule of 4-hydroxycoumarin reacted with ammonium
Acknowledgments
acetate as
a nitrogen source to yield β-aminobenzopyran-2-
one (B). The reaction is followed via a Michael-type additionof
β-aminobenzopyran-2-one to intermediate A. Subsequently, cy-
clization followed by dehydration of intermediate C, yield the
desired molecule 1a. As above mentioned, in contrast of our
prediction, “anomeric based oxidation” (ABO) did not occur in the
course of reactions [35-36].
We thanks the Bu-Ali Sina University and Iran National Science
Foundation (INSF) (Grant Number: 98001912) for financial support
to our research group.
Supplementary materials
Supplementary material associated with this article can be
found, in the online version, at doi:10.1016/j.molstruc.2020.129294.
4. Conclusion
As a conclusion, a novel nanomagnetic catalyst with urea link-
ers was prepared and fully characterized using various techniques.
The applied catalyst has both acidic and H-bond donor-acceptor
sites so that it can use as a dual role catalytic system. Afterward,
Fe3O4@SiO2@(CH2)3-urea-quinoline sulfonic acid chloride as an ef-
ficient and recoverable catalyst was used for the preparation of
coumarine containing DHPs moieties under solvent-free conditions.
Simple and mild procedure, high to excellent yields of products,
short reaction times, disuse of solvent, lower temperature rather
than previous works, easy work-up using water and facile separa-
References
[1] (a) A.A. Al-Amiery, R.I.H. Al-Bayati, K.Y. Saour, M.F. Radi, Cytotoxicity, antiox-
idant, and antimicrobial activities of novel 2-quinolone derivatives derived
from coumarin, Res. Chem. Intermed 38 (2012) 559–569; (b) W.-.H. Zhan,
J.-.L. Hua, Y.-.H. Jin, X. Teng, H. Tian, The synthesis and characterization of
novel coumarin-containing cyanine dyes via “Click” chemistry, Res. Chem. In-
termed 34 (2008) 229–239; (c) A. Kotali, I.S. Lafazanis, P.A. Harris, A novel and
facile synthesis of 7,8-diacylcoumarins, Tetrahedron Lett 48 (2007) 7181–7183.
[2] T. Devji, C. Reddy, C. Woo, S. Awale, S. Kadota, D. Carrico-Moniz, Pancreatic
anticancer activity of a novel geranylated coumarin derivative, Bioorg. Med.
Chem. Lett 21 (2011) 5770–5773.
10

H. Saffarian, F. Karimi, M. Yarie et al.
Journal of Molecular Structure 1224 (2020) 129294
[3] H. Xue, X. Lu, P. Zheng, L. Liu, C. Han, J. Hu, Z. Liu, T. Ma, Y. Li, L. Wang, Z. Chen,
G. Liu, Highly suppressing wild-type HIV-1 and Y181C mutant HIV-1 strains
by 10-chloromethyl-11-demethyl-12-oxo-calanolide A with druggable profile, J.
Med. Chem 53 (2010) 1397–1401.
alyzed by p-dodecylbenezenesulfonic acid in aqueous media, Synthesis (Mass)
12 (2004) 2001-2005; (e) K. Venkatesan, S.S. Pujari, K.V. Srinivasan, Proline–
catalyzed simple and efficient synthesis of 1,8-dioxo-decahydroacridines in
aqueous ethanol medium, Synth. Commun 39 (2008) 228–241; (f) B. Dam,
S. Nandi, A. Kumar Pal, An efficient ‘on-water’ synthesis of 1,4-dihydropy-
[4] A. Manvar, A. Bavishi, A. Radadiya, J. Patel, V. Vora, N. Dodia, K. Rawal, A. Shah,
Diversity oriented design of various hydrazides and their in vitro evaluation
against Mycobacterium tuberculosis H37Rv strains, Bioorg. Med. Chem. Lett 21
(2011) 4728–4731.
ridines using Fe3O4@SiO2 nanoparticles as
Lett 55 (2014) 5236–5240.
a reusable catalyst, Tetrahedron
[21] (a) M. Gilanizadeh, B. Zeynizadeh, Cascade synthesis of fused polycyclic
dihydropyridines by Ni–Zn–Fe hydrotalcite (HT) immobilized on silica–
coated magnetite as magnetically reusable nanocatalyst, Res. Chem. In-
termediat 45 (2019) 2811–2825; (b) B. Zeynizadeh, S. Rahmani, Sul-
fonyl-bridged (copper-immobilized nickel ferrite) with activated montmo-
[5] J.Y. Yeh, M.S. Coumar, J.T. Horng, H.Y. Shiao, F.M. Kuo, H.L. Lee, I.C. Chen,
C.W. Chang, W.F. Tang, S.N. Tseng, C.J. Chen, S.R. Shih, J.T. Hsu, C.C. Liao,
Y.S. Chao, H.P. Hsieh, Anti-influenza drug discovery: structure-activity relation-
ship and mechanistic insight into novel angelicin derivatives, J. Med. Chem 53
(2010) 1519–1533.
rillonite, [(NiFe2O4@Cu)SO2(MMT)]:
ble clay nanocomposite systems towards Hantzsch synthesis of coumar-
in-based 1,4-dihydropyridines, RSC Adv (2019) 8002–8015; (c) A. Shaa-
a new class of magnetically separa-
[6] L. Piazzi, A. Cavalli, F. Colizzi, F. Belluti, M. Bartolini, F. Mancini, M. Recanatini,
V. Andrisano, A. Rampa, Multi-target-directed coumarin derivatives: hAChE
and BACE1 inhibitors as potential anti-Alzheimer compounds, Bioorg. Med.
Chem. Lett 18 (2008) 423–436.
[7] C.A. Kontogiorgis, D.J. Hadjipavlou-Litina, Synthesis and biological evaluation of
novel coumarin derivatives with a 7-azomethine linkage, Bioorg. Med. Chem.
Lett 14 (2004) 611–614.
9
bani, S. Shaabani, M. Seyyedhamzeh, M. Hamidzad Sangachin, F. Hajishaa-
banha, Guanidinium-based sulfonic acid: an efficient Brønsted acid organocat-
alyst for the synthesis of fused polycyclic dihydropyridines in water, Res.
Chem. Intermed 42 (2016) 7247–7256; (d) M. Kidwai, S. Kukreja, S. Ras-
togi, K. Singhal, N.K. Mishra, An aqua mediated facile synthesis of con-
[8] A.G. Kidane, H. Salacinski, A. Tiwari, K.R. Bruckdorfer, A.M. Seifalian, Antico-
formationally restricted polycyclic dihydropyridines, Indian J. Chem.
B 53
agulant and antiplatelet agents:
their clinical and device application(s) to-
(2014) 605–609; (e) D.I. Brahmbhatt, U.R. Pandya, G.B. R.aolji, Synthesis
ꢀ
ꢀ
gether with usages to engineer surfaces, Biomacromolecules 5 (2004) 798–813.
[9] G. Appendino, E. Mercalli, N. Fuzzati, L. Arnoldi, M. Stavri, S. Gibbons,
M. Ballero, A. Maxia, Antimycobacterial coumarins from the sardinian giant
fennel (Ferula communis), J. Nat. Prod 67 (2004) 2108–2110.
of 4-aryl-1,4-dihydro-dicoumarino[4,3-b;3 ,4 -e]pyridines, Heterocycl. Commun
10 (2004) 419–422.
[22] (a) D. Wang, D. Astruc, Fast-growing field of magnetically recyclable nanocata-
lysts, Chem. Rev 114 (2014) 6949–6985; (b) D. Zhang, C. Zhou, Z. Sun, L.Z. Wu,
[10] K.V. Sashidhara, J.N. Rosaiah, A. Kumar, G. Bhatia, A.K. Khanna, Synthesis of
novel benzocoumarin derivatives as lipid lowering agents, Bioorg. Med. Chem.
Lett. 20 (2010) 3065–3069.
C.H. Tung, T. Zhang, Magnetically recyclable nanocatalysts (MRNCs):
a ver-
satile integration of high catalytic activity and facile recovery, Nanoscale
4
(2012) 6244–6255; (c) B. Karimi, F. Mansouri, H.M. Mirzaei, Recent applica-
tions of magnetically recoverable nanocatalysts in C-C and C-X coupling reac-
tions, ChemCatChem 7 (2015) 1736–1789; (d) M. Mokhtary, Recent advances in
catalysts immobilized on magnetic nanoparticles, J. Iran. Chem. Soc 13 (2016)
1827–1845; (e) R. Hudson, Y. Feng, R.S. Varmaand, A. Moores, Bare magnetic
nanoparticles: sustainable synthesis and applications in catalytic organic trans-
formations, Green Chem 16 (2014) 4493–4505.
[11] O.O. Ajani, O.C. Nwinyi, Microwave-assisted synthesis and eval-
uation of antimicrobial activity of 3-{3-(s-aryl and s-heteroaro-
matic)acryloyl}-2H-chromen-2-one derivatives, J. Heterocyclic Chem 47
(2010) 179–187.
[12] G. Melagraki, A. Afantitis, O. Igglessi-Markopoulou, A. Detsi, M. Koufaki, C. Kon-
togiorgis, D.J. Hadjipavlou-Litina, Synthesis and evaluation of the antioxidant
and anti-inflammatory activity of novel coumarin-3-aminoamides and their al-
pha-lipoic acid adducts, Eur. J. Med. Chem 44 (2009) 3020–3026.
[23] (a) V. Polshettiwar, R. Luque, A. Fihri, H. Zhu, M. Bouhrara, J.-.M. Basset,
Magnetically recoverable nanocatalysts, Chem. Rev. 111 (2011) 3036–3075; (b)
R.B.N. Baig, R.S. Varma, Magnetically retrievable catalysts for organic synthesis,
Chem. Commun 49 (2013) 752–770; (c) D. Zhang, C. Zhou, Z. Sun, L.Z. Wu,
[13] (a) W.A. Carroll, K.A. Agrios, R.J. Altenbach, S.A. Buckner, Y. Chen, M.J. Cogh-
lan, A.V. Daza, I. Drizin, M. Gopalakrishnan, R.F. Henry, M.E. Kort, P.R. Kym,
I. Milicic, J.C. Smith, R. Tang, S.C. Turner, K.L. Whiteaker, H. Zhang, J.P. Sullivan,
Synthesis and structure-activity relationships of a novel series of tricyclic di-
hydropyridine-based KATP openers that potently inhibit bladder contractions
in vitro, J. Med. Chem 47 (2004) 3180–3192; (b) T. Li, X. Feng, C. Yao, C. Yu,
B. Jiang, S. Tu, Design and efficient synthesis of A-278637 derivatives as poten-
tial potassium channel opener, Bioorg. Med. Chem. Lett 21 (2011) 453–455.
[14] S. Shukla, R.W. Robey, S.E. Bates, S.V. Ambudkar, The Calcium channel block-
ers, 1,4-dihydropyridines, are substrates of the multidrug resistance-linked ABC
drug transporter, ABCG2, Biochemistry 45 (2006) 8940–8951.
C.H. Tung, T. Zhang, Magnetically recyclable nanocatalysts (MRNCs):
satile integration of high catalytic activity and facile recovery, Nanoscale
a ver-
4
(2012) 6244–6255; (d) S. Laurent, D. Forge, M. Port, A. Roch, C. Robic, L.V. Elst,
R.N. Muller, Magnetic iron oxide nanoparticles: synthesis, stabilization, vector-
ization, physicochemical characterizations, and biological applications, Chem.
Rev 108 (2008) 2064–2110.
[24] (a) M. Nasrollahzadeh, M. Sajjadi, H.A. Khonakdar, Synthesis and characteri-
zation of novel Cu(II) complex coated Fe3O4@SiO2 nanoparticles for catalytic
performance, J. Mol. Struct 1161 (2018) 453–463; (b) Q.M. Kainz, O. Reiser,
Polymer- and dendrimer-coated magnetic nanoparticles as versatile supports
for catalysts, scavengers, and reagents, Acc. Chem. Res 47 (2014) 667–677.
[25] (a) W. Xie, H. Wang, Immobilized polymeric sulfonated ionic liquid on
core-shell structured Fe3O4/SiO2 composites: a magnetically recyclable cata-
lyst for simultaneous transesterification and esterifications of low-cost oils to
biodiesel, Renew. Energy 145 (2020) 1709–1719; (b) W. Xie, Y. Han, H. Wang,
Magnetic Fe3O4/MCM-41 composite-supported sodium silicate as heteroge-
neous catalysts for biodiesel production, Renew. Energy 125 (2018) 675–681;
(c) W. Xie, X. Zang, Lipase immobilized on ionic liquid-functionalized mag-
[15] (a) S. Indumathi, R. Karthikeyan, A.J. Abdul Nasser, A. Idhayadhulla, R.S. Ku-
mar, Anticonvulsant, analgesic and anti-inflammatory activities of some novel
pyrrole and 1,4-dihydropyridine derivatives, J. Chem. Pharm. Res
7 (2015)
434–440; (b) S. Ulloora, S. Kumar, R. Shabaraya, A.V. Adhikari, New dihydropy-
ridine derivatives: anti-inflammatory, analgesic and docking studies, Med.
Chem. Res 22 (2013) 1549–1562.
[16] J. Marco-Contelles, R. Leon, C. Rios, A. Samadi, V. Andrisano, O. Huertas,
X. Barril, F.J. Luque, M.I. Rodriguez-Franco, B. Lopez, M.G. Lopez, A.G. Garcia,
M.C. Carreiras, M. Villarroya, Tacripyrines, the first tacrine-dihydropyridine hy-
brids, as multitarget-directed ligands for the treatment of Alzheimer’s disease,
J. Med. Chem 52 (2009) 2724–2732.
netic silica composites as
a magnetic biocatalyst for production of tran-
s-free plastic fats, Food Chem 257 (2018) 15–22; (d) W. Xie, J. Wang, Enzy-
matic production of biodiesel from soybean oil by using immobilized lipase
on Fe3O4/Poly(styrene-methacrylic acid) magnetic microsphere as a biocata-
lyst, Energ. Fuel 28 (2014) 2624–2631; (e) W. Xie, F. Wan, Basic ionic liquid
functionalized magnetically responsive Fe3O4@HKUST-1 composites used for
biodiesel production, Fuel 220 (2018) 248–256.
[17] (a) W.A. Denny, G.J. Atwell, B.C. Baguley, L.P.G. Wakelin, Potential antitumor
agents. 44. Synthesis and antitumor activity of new classes of diacridines: im-
portance of linker chain rigidity for DNA binding kinetics and biological ac-
tivity, J. Med. Chem 28 (1985) 1568–1574; (b) G.W. Rewcastle, G.J. Atwell,
D. Chambers, B.C. Baguley, W.A. Denny, Potential antitumor agents. 46. Struc-
ture-activity relationships for acridine monosubstituted derivatives of the
antitumor agent N-[2-(dimethylamino)ethyl]-9-aminoacridine-4-carboxamide, J.
Med. Chem 29 (1986) 472–477.
[26] T.P. Vishnyakova, I.A. Golubeva, E.V. Glebova, Substituted ureas. methods of
synthesis and applications, Russ. Chem. Rev 54 (1985) 249.
[27] B. Atashkar, M.A. Zolfigol, S. Mallakpour, Applications of biological urea-based
catalysts in chemical processes, Mol. Catal 452 (2018) 192–246.
[28] (a) M.M. Heravi, V. Zadsirjan, M. Dehghani, T. Ahmadi, Towards click chem-
istry: multicomponent reactions via combinations of name reactions, Tetra-
hedron 74 (2018) 3391–3457; (b) I.A. Ibarra, A Islas Jácome, E. González
[18] Y.L.N. Murthy, A. Rajack, M.T. Ramji, J.J. babu, Ch. Praveen, K.A. Lakshmic, De-
sign, solvent free synthesis, and antimicrobial evaluation of 1,4 dihydropy-
ridines, Bioorg. Med. Chem. Lett 22 (2012) 6016–6023.
[19] S. Girault, P. Grellier, A. Berecibar, L. Maes, E. Mouray, P. Lemière,
M.A. Debreu, E.Davioud Charvet, C. Sergheraert, Antimalarial, antit-
rypanosomal, and antileishmanial activities and cytotoxicity of bis
Zamora, Synthesis of polyheterocycles via multicomponent reactions, Org.
Biomol. Chem 16 (2018) 1402–1418; (c) T. Ahmadi, G. Mohammadi Ziarani,
P. Gholamzadeh, H. Mollabagher, Recent advances in asymmetric multicom-
ponent reactions (AMCRs), Tetrahedron: Asymmetry 28 (2017) 708–724; (d)
D. Zhang, W. Hu, Asymmetric multicomponent reactions based on trapping of
active intermediates, Chem. Rec 17 (2017) 739–753.
(9-amino-6-chloro-2-methoxyacridines):
Chem. 43 (2000) 2646–2654.
influence of the linker, J. Med.
[20] (a) J. Davarpanah, M. Ghahremani, O. Najafi, Synthesis of 1,4-dihydropyri-
dine and polyhydroquinoline derivatives via Hantzsch reaction using nicotinic
acid as
(b) T.S. Bade, H.P. Ebrahimi, T.A. Alsalim, S.J.J. Titinchi, H.S. Abbo, Z. Boland-
nazard, A. Ebrahimie, novel series of 1, 4-dihydropyridine (DHP) deriva-
a
green and reusable catalyst, J. Mol. Struct 1177 (2019) 525–535;
[29] (a) S. Garbarino, D. Ravelli, S. Protti, A. Basso, Photoinduced multicompo-
nent reactions, Angew. Chem. Int. Ed 55 (2016) 15476–15484; (b) L. Levi,
T.J.J. Muller, Multicomponent syntheses of functional chromophores, Chem.
Soc. Rev 45 (2016) 2825–2846; (c) M. Haji, Multicomponent reactions: a sim-
ple and efficient route to heterocyclic phosphonates, Beilstein J. Org. Chem
12 (2016) 1269–1301; (d) T. Zarganes Tzitzikas, A.L. Chandgude, A. Dömling,
Multicomponent reactions, union of MCRs and beyond, Chem. Rec 15 (2015)
981–996.
A
tives bearing thiazolidin-4-one: from synthesis to structure, J. Mol. Struct
1138 (2017) 136–148; (c) M. Li, Z. Zuo, L. Wen, S. Wang, Microwave-as-
sisted combinatorial synthesis of hexa-substituted 1,4-dihydropyridines scaf-
folds using one-pot two-step multicomponent reaction followed by a S-alky-
lation, J. Comb. Chem 10 (2008) 436–441; (d) T.S. Jin, J.S. Zhang, T.T. Guo,
A.Q. Wang, T.S. Li, One-pot clean synthesis of 1,8-dioxo-decahydroacridines cat-
11

H. Saffarian, F. Karimi, M. Yarie et al.
Journal of Molecular Structure 1224 (2020) 129294
[30] (a) M.A. Zolfigol, E. Kolvari, A. Abdoli, M. Shiri, Synthesis of new tripodal
Hantzsch 1,4-dihydropyridines under solvent-free condition and their conver-
sion to the corresponding tripodal pyridines, Mol. Divers 14 (2010) 809–813;
(b) N. Koukabi, E. Kolvari, A. Khazaei, M.A. Zolfigol, B. Shirmardi-Shaghasemi,
H.R. Khavasi, Hantzsch reaction on free nano-Fe2O3 catalyst: excellent reac-
tivity combined with facile catalyst recovery and recyclability, Chem. Com-
mun 47 (2011) 9230–9233; (c) D. Habibi, M.A. Zolfigol, M. Safaee, Synthe-
as
a
heterogeneous and recyclable catalyst for oxidative aromatization of
Hantzsch 1,4-dihydropyridines at room temperature, J. Iran Chem. Soc 11
(2014) 1593–1597.
[32] (a) M.A. Zolfigol, M. Navazeni, M. Yarie, R. Ayazi Nasrabadi, Application of a
biological-based nanomagnetic catalyst in the synthesis of bis-pyrazols and
pyrano[3,2-c]pyrazoles, Appl. Organometal. Chem 31 (2017) e3633–e3639; (b)
L. Mohammadi, M.A. Zolfigol, A. Khazaei, M. Yarie, S. Ansari, S. Azizian,
M. Khosravi, Synthesis of nanomagnetic supported thiourea–copper(I) cata-
lyst and its application in the synthesis of triazoles and benzamides, Appl.
Organometal. Chem 32 (2017) e3933–e3945; (c) M.A. Zolfigol, M. Navazeni,
M. Yarie, R. Ayazi Nasrabadi, Application of biological-based nano and nano
magnetic catalysts in the preparation of arylbispyranylmethanes, RSC. Adv 6
sis of 1,4-dihydropyridines bearing
a carbamate moiety on the 4-position,
J. Chem (2013), doi:10.1155/2013/495982; (d) M.A. Zolfigol, M.J. Mokhlesi,
The first report on the synthesis of new Hantzsch N-ethyldimetyl acetal-1,4-
dihydropyridines with aldehyde synthon under microwave irradiation, Iran.
Chem. Soc
5 (2008) S91–S96, doi:10.1155/2013/495982; (e) M.A. Zolfigol,
P. Salehi, M. Safaiee, An efficient and eco-friendly procedure for the syn-
thesis of Hantzsch ethyl 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylates
(2016) 92862–92868; (d) M. Torabi, M. Yarie, M.A. Zolfigol, Synthesis of a
novel and reusable biological urea based acidic nanomagnetic catalyst: appli-
cation for the synthesis of 2-amino-3-cyano pyridines via cooperative vinylo-
gous anomeric based oxidation, Appl. Organometal. Chem 33 (2019) e4933; (e)
P. Ghasemi, M. Yarie, M.A. Zolfigol, A.A. Taherpour, Ionically tagged magnetic
nanoparticles with urea linkers: application for preparation of 2-aryl-quino-
line-4-carboxylic acids via an anomeric-based oxidation mechanism, ACS
Omega 5 (2020) 3207–3217.
under mild and green conditions, Lett. Org. Chem
3 (2006) 153–156,
doi:10.1155/2013/495982; (f) M.A. Zolfigol, P. Salehi, A. Khorramabadi-Zad,
M.J. Shayegh, Iodine-catalyzed synthesis of novel Hantzsch N-hydroxymethyl
1,4-dihydropyridines under mild conditions, Mol. Catal. A- Chem 261 (2007)
88–92, doi:10.1155/2013/495982; (g) M.A. Zolfigol, M. Safaiee, Synthesis of 1,4-
dihydropyridines under solvent-free conditions, Synlett 5 (2004) 0827–0828,
doi:10.1155/2013/495982.
[33] S. Qu, H. Yang, D. Ren, S. Kan, G. Zou, D. Li, M. Li, Magnetite nanoparticles pre-
pared by precipitation from partially reduced ferric chloride aqueous solutions,
J. Colloid Interf. Sci 215 (1999) 190–192.
[31] (a) M.A. Zolfigol, M.H. Zebarjadian, M.M. Sadegh, I. Mohammadpoor-Baltork,
H.R. Memarian, M. Shamsipur, Chemoselective oxidation of 1,4-dihydropy-
ridines with [NO+.Crown.H(NO3)2−], Synthetic Commun. 31 (2001) 929–934;
(b) M.A. Zolfigol, F. Shirini, A. Ghorbani Choghamarani, I. Mohammadpoor-Bal-
tork, Silica modified sulfuric acid/NaNO2 as a novel heterogeneous system for
the oxidation of 1,4-dihydropyridines under mild conditions, Green Chem 4
(2002) 562–564; (c) M.A. Zolfigol, A. Ghorbani Choghamarani, S. Dialameh,
M.M. Sadeghi, I. Mohammadpoor-Baltork, H.R. Memarian, An efficient method
for the oxidation of 1,4-dihydropyridines under mild and heterogeneous con-
ditions via in situ generation of NOCl, J. Chem. Res 18 (2003) 18–20; (d)
M.A. Zolfigol, F. Shirini, A. Ghorbani Choghamarani, I. Mohammadpoor-Bal-
tork, Silica chloride/NaNO2 as a novel heterogeneous system for the oxida-
tion of 1,4-dihydropyridines under mild conditions via in situ generation of
NOCl, Phosphorus Sulfur 178 (2003) 1709–1715; (e) M.A. Zolfigol, A. Ghorbani
Choghamarani, M. Shahamirian, M. Safaiee, I. Mohammadpoor-Baltork, S. Mal-
lakpour, M. Abdollahi-Alibeik, 4-Phenyl-1,2,4-triazole-3,5-dione as a novel and
reusable reagent for the aromatization of 1,4-dihydropyridines under mild con-
ditions, Tetrahedron Lett 46 (2005) 5581–5584; (f) M. Safaiee, M.A. Zolfigol,
M. Tavasoli, M. Mokhlesi, Application of silica vanadic acid [SiO2-VO(OH)2]
[34] (a) D.L. Comins, K. Higuchi, D.W. Young, Dihydropyridine préparation and ap-
plication in the synthesis of pyridine derivatives, Adv. Heterocycl. Chem 110
(2013) 175–235; (b) T. Hosseinnejad, M. Omrani-Pachin, M.M. Heravi, Joint
computational and experimental investigations on the synthesis and proper-
ties of Hantzsch-type compounds: an overview, Curr. Org. Chem 23 (2019)
1421–1438; (c) V.G. Santos, M.N. Godoi, T. Regiani, F.H.S. Gama, M.B. Coelho,
R.O.M.A. Souza, M.N. Eberlin, S.J. Garden, The multicomponent Hantzsch re-
action: comprehensive mass Spectrometry monitoring using charge-tagged
reagents, Chem. Eur.
J 20 (2014) 12808–12816; (d) W. Jie-Ping, L. Yunyun,
Recent advances in new multicomponent synthesis of structurally diversified
1,4-dihydropyridines, RSC Adv 2 (2012) 9763–9777.
[35] M. Yarie, Catalytic anomeric based oxidation, Iran. J. Catal 7 (2017) 85–88 and
references cited therein.
[36] M. Yarie, Catalytic vinylogous anomeric based oxidation (Part I), Iran. J. Catal
10 (2020) 79–83 and references cited therein.
12