Gallic acid grafted to amine-functionalized magnetic nanoparticles as a proficient catalyst for environmentally friendly synthesis of α-aminonitriles

Article abstract of DOI:10.1002/aoc.4810

An effective approach of one-pot catalytic Strecker reaction between aromatic aldehydes, aniline or toluidine and trimethylsilyl cyanide in the presence of amine-functionalized Fe₃O₄@SiO₂ nanoparticles grafted with gallic

Full text of DOI:10.1002/aoc.4810

Received: 28 October 2018
DOI: 10.1002/aoc.4810
Revised: 2 January 2019
Accepted: 3 January 2019
F U L L P A P E R
Gallic acid grafted to amine‐functionalized magnetic
nanoparticles as a proficient catalyst for environmentally
friendly synthesis of α‐aminonitriles
Ali Maleki
| Sepide Azadegan | Jamal Rahimi
Catalysts and Organic Synthesis Research
Laboratory, Department of Chemistry,
Iran University of Science and
An effective approach of one‐pot catalytic Strecker reaction between aromatic
aldehydes, aniline or toluidine and trimethylsilyl cyanide in the presence of
amine‐functionalized Fe3O4@SiO2 nanoparticles grafted with gallic acid (GA)
as a powerful catalyst was developed. The fabricated reusable catalyst demon-
strated high efficiency in the synthesis of α‐aminonitriles along with facile
work‐up procedure. Fe3O4@SiO2‐NH2‐GA was characterized by Fourier
transform‐infrared spectroscopy, scanning electron microscopy image,
vibrating‐sample magnetometer curve, energy‐dispersive X‐ray analysis and
thermogravimetric analysis.
Technology, Tehran 16846‐13114, Iran
Correspondence
Ali Maleki, Catalysts and Organic
Synthesis Research Laboratory,
Department of Chemistry, Iran University
of Science and Technology, Tehran 16846‐
13114, Iran.
Email: maleki@iust.ac.ir
Funding information
KEYWORDS
Research Council of the Iran University of
Science and Technology
aminonitrile, Fe3O4/SiO2 nanocomposite, gallic acid, heterogeneous green nanocatalyst, multi‐
component reaction
1 | INTRODUCTION
It is widely acknowledged that there is a growing need
for more environmentally acceptable processes and cata-
Multi‐component reaction (MCR) processes are of great
interest, not only because of their atom economy but also
for their application in diversity‐oriented synthesis and in
preparing libraries for the screening of functional mole-
cules.[1] The Strecker reaction, for example, is known as
a significant, practical, manageable and economic tool
with wide‐spreading usage in synthesis of α‐
aminonitriles. Intermediates of this useful MCR are suc-
cessfully used also in the synthesis of abundant pharma-
ceutically important indole alkaloids, like hirsutine,[2] or
eburnamonine,[3] which can have a role as potent antihy-
pertensive agents. Regarding the various usages of α‐
aminonitriles in preparing wide‐varied amino acids,
amides, diamines and nitrogen‐containing heterocycles,
profound impact of these important substances can be
recognized.[4–6] An innumerable number of acid‐
catalyzed Strecker reactions, including homogeneous
Lewis acids,[7–9] heterogeneous Lewis acids[10,11] and also
heterogeneous Brønsted acids[12,13] were reported.
lysts in the chemical industry. This trend has become
known as green chemistry or sustainable technol-
ogy.[14,15] Surface functionalization of magnetic nanopar-
ticles (MNPs) is a well‐designed way to bridge the gap
between heterogeneous and homogeneous catalysis. The
introduction of MNPs in a variety of solid matrices allows
the combination of well‐known procedures for catalyst
heterogenization with techniques for magnetic separa-
tion.[16–18] So, these types of catalysts play a vital role in
approaching the green chemistry goal. Beside other cata-
lysts, MNP catalysts show excellent function in synthesis
of α‐aminonitriles as well.[19,20]
Plenty of successful examples of silica‐coated MNPs in
different synthesis areas such as carbon–carbon cou-
pling,[21,22] acetylation,[23] oxidation,[24] hydrogenation[25]
and asymmetric synthesis[26] are reported.
These powerful silica‐based magnetically recoverable
nanocatalysts have the following attractive features: (1)
good dispersion of the active species (usually noble metal
Appl Organometal Chem. 2019;e4810.
wileyonlinelibrary.com/journal/aoc
© 2019 John Wiley & Sons, Ltd.
1 of 7
https://doi.org/10.1002/aoc.4810

2 of 7
MALEKI ET AL.
NPs) on the magnetic support; (2) sufficient binding
strength between the active species and magnetic support
to enable recycling; (3) good chemical inertness of the
magnetic support; (4) high saturation magnetization to
facilitate magnetic separation; (5) soft ferromagnetism
for redispersion; (6) a wide variety of silylating agents
can be used, allowing pendant functional groups in the
inorganic framework; (7) attachment is easier on silica
surfaces than on organic polymeric supports (which have
a high number of cross‐linking bonds); (8) low cost, ready
availability, mechanical robustness and straightforward
synthesis; and (9) a quasi‐homogeneous state can be
achieved.[14]
Gallic acid (GA) is a yellowish white crystal having a
molecular mass of 170.12 g mol−1, melting point 250°C
and water solubility 1.1% at 20°C.[27] It is a natural plant
triphenol, and its derivatives have been extensively evalu-
ated for their antitumor activity against a variety of cell
lineages. Some GA derivatives such as methyl, propyl,
octyl and dodecyl gallates are widely used in food
manufacturing as antioxidants, as well as in the pharma-
ceutical and cosmetic industries. Previous studies have
shown that these compounds have potent therapeutic
properties, including antitumoral, antimicrobial and anti-
viral, as well as being potent antioxidants, acting as scav-
engers of reactive oxygen species.[28–31]
trimethylsilyl cyanide (TMSCN) in excellent yields
(Scheme 1). With the aim of a green approach to α‐
aminonitriles, this is the first report on the application
of Fe3O4@SiO2‐NH2‐GA in this procedure.
2 | EXPERIMENTAL
2.1 | Fe3O4@SiO2‐NH2‐GA preparation
[32]
Initially, 1.0 g of freshly prepared Fe3O4@SiO2‐NH2
was dispersed in a minimum amount of dry (anhydrous)
toluene. A homogenous mixture of 0.6 g GA in dry tolu-
ene should be added drop‐wise to the dispersed
Fe3O4@SiO2‐NH2 at room temperature and under mild
stirring conditions. Finally, 10 mol% of ZrCl4 is also
needed as co‐catalyst. Next, refluxing of the aforemen-
tioned mixture for 24 hr gave the desired nanocatalyst.
Eventually, washing and drying resulted in the
Fe3O4@SiO2‐NH2‐GA being applicable as a proper het-
erogeneous nanocatalyst.
2.2 | Typical procedure for the synthesis
of α‐aminonitrile derivatives via
multi‐component reaction
Herein, design and development of amine‐
functionalized silica‐based MNPs grafting with GA as an
effective recoverable catalyst was reported for the
Strecker MCR to afford α‐aminonitriles 4a–y starting
from an aromatic aldehyde, aniline or toluidine and
A mixture of an aromatic aldehyde (1 mmol), aniline or
toluidine (1 mmol) and TMSCN (1 mmol) in ethanol (5
mL) in the presence of 40 mg of Fe3O4@SiO2‐NH2‐GA
was stirred at room temperature. After completion of
the reaction, which was indicated by thin‐layer chroma-
tography (TLC), the MNP catalyst was separated magnet-
ically and the desired products were achieved by
crystallization from ethanol.
SCHEME 1 Nano‐Fe3O4@SiO2‐NH2@GA‐catalysed protocol
FIGURE 1 Comparative Fourier
transform‐infrared (FT‐IR) spectra of
nano‐Fe3O4@SiO2‐NH2@GA and previous
catalyst manufacturing steps

MALEKI ET AL.
3 of 7
O, N and Fe signals implied that the silica layer was
coated on the surface of the Fe3O4 NPs and N linkages
were formed satisfyingly. As it can be seen, the weight
percentage (W%) of carbon and oxygen elements have
been increased after GA loading onto the surface of the
MNPs (Figure 2a and b).
3 | RESULTS AND DISCUSSION
3.1 | Characterization of the catalyst
3.1.1 | Fourier transform‐infrared spectra
The comparative Fourier transform‐infrared (FT‐IR) spec-
tra of the synthesized catalyst with the previous
manufacturing levels are presented (Figure 1). Clearly,
vibration peaks of Fe‐O, Si‐OH and Si‐O‐Si were associated
with related ones in the other spectrums. The absorption
bands at 1383 and 1657 cm−1 were related to C‐C stretching
and C‐H vibrations, respectively,[33] and the existence of an
aromatic ring in the synthesized nanocatalyst could be
ascertained. Finally, bands that appeared at 1504 cm−1
and were attributed to the N‐H and C=O at 1680 cm−1
approved the successful fabrication.
3.1.3 | Morphology and particle size of
nano‐Fe3O4@SiO2‐NH2@GA
The corresponding scanning electron microscopy (SEM)
images of Fe3O4@SiO2‐NH2@GA revealed that spherical
3.1.2 | Energy‐dispersive X‐ray analysis
The components of the synthesized catalyst were con-
firmed using energy‐dispersive X‐ray (EDX) analysis
(Figure 2). As shown in the figure, the presence of Si,
FIGURE 3 (a,b) Scanning electron microscopy (SEM) images of
nano‐Fe3O4@SiO2‐NH2@GA and (c) related particle size
distribution diagram
FIGURE 2 Energy‐dispersive X‐ray (EDX) analysis of (a) nano‐
Fe3O4@SiO2‐NH2 and (b) nano‐Fe3O4@SiO2‐NH2@GA

4 of 7
MALEKI ET AL.
particles of the obtained catalyst located monotonously
and no agglomeration occurred during the process
(Figure 3a and b). Furthermore, the calculated average
particle diameter was about 20 nm from the diameters
of 52 particles (Figure 3c).
3.1.4 | Vibrating‐sample magnetometer
study
Figure 4 shows the hysteresis loops as a function of the
magnetic field, or the M vs. H curve related to Fe3O4,
Fe3O4@SiO2, Fe3O4@SiO2‐NH2 and Fe3O4@SiO2@NH2‐
GA nanocomposite. The saturation magnetizations (Ms)
FIGURE 5 Thermogravimetric analysis (TGA) curve of nano‐
Fe3O4@SiO2‐NH2‐GA
of
Fe3O4,
Fe3O4@SiO2,
Fe3O4@SiO2‐NH2
and
Fe3O4@SiO2@NH2‐GA were measured as 61.50, 40.28,
21.30 and 19.1 emu g−1, respectively. The decrease in sat-
uration magnetization was most likely due to the exis-
tence of coated layers on the surface of the MNPs,
which formed during the nanocatalyst manufacturing
process.[34] The high resulting magnetic saturation allows
easy separation of the nanocatalyst from the reaction
media within a few seconds. The low coercivity of 8.64
TABLE 1 Screening of reaction condition and catalyst efficiency
investigation
Temp. Time
Yield
Entry
Catalyst
(°C) (min) Solvent (%)
1
2
3
4
5
6
Fe3O4
r.t.
r.t.
r.t.
10
10
10
EtOH 65
EtOH 78
EtOH 80
EtOH 99
EtOH 98
EtOH 90
Fe3O4@SiO2
Fe3O4@SiO2‐NH2
Oe
for
Fe3O4@SiO2@NH2‐GA
confirmed
the
Fe3O4@SiO2‐NH2‐GA Reflux 10
superparamagnetic property of the nanocomposite.
Fe3O4@SiO2‐NH2‐GA
r.t.
r.t.
10
75
Silica‐based ionic
liquid[36]
3.1.5 | Thermogravimetric analysis
7
Cerium (III)
chloride[37]
r.t.
85
CH3N 95
Figure 5 illustrates the thermogravimetric analysis (TGA)
curve of GA nanocatalyst. Weight loss at temperatures
below 200°C can be attributed to water desorption from
the surface of the silica layer, while weight loss above
600°C is associated with the release of the structure
water.[35] Mass loss at temperature ~210–300°C corre-
sponding to GA and another at ~400–600°C is due to
the organic part of 3‐aminopropylsilica.
8
L‐Proline[38]
[39]
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
120
180
10
CH3N 95
CH2Cl2 97
EtOH Trace
H2O 65
9
MgI2
10
11
12
13
14
15
–
Fe3O4@SiO2‐NH2‐GA
Fe3O4@SiO2‐NH2‐GA
Fe3O4@SiO2‐NH2‐GA
Fe3O4@SiO2‐NH2‐GA
20
10
CH3N 90
DMSO 68
CH2Cl2 46
EtOH 60
20
20
Fe3O4@SiO2‐NH2‐GA
10
(10 mg)
16
17
18
19
20
21
Fe3O4@SiO2‐NH2‐GA
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
10
10
10
10
10
10
EtOH 84
EtOH 90
EtOH 98
EtOH 98
EtOH 98
EtOH 56
(20 mg)
Fe3O4@SiO2‐NH2‐GA
(30 mg)
Fe3O4@SiO2‐NH2‐GA
(40 mg)
Fe3O4@SiO2‐NH2‐GA
(50 mg)
Fe3O4@SiO2‐NH2‐GA
(60 mg)
GA
FIGURE 4 Magnetization curve of nano‐Fe3O4@SiO2‐NH2‐GA
in comparison with its comparative components
GA, gallic acid.

MALEKI ET AL.
5 of 7
9). Solvent screening revealed that the reaction performed
well in EtOH compared with other suggested solvents
with different polarities under identical conditions
(entries 5 and 11–14). To find the best reaction condi-
tions, a set of experiments was carried out by changing
the catalyst amount. According to the results, 40 mg of
catalyst is sufficient to promote the reaction with satisfac-
tory yield (entries 15–21).
3.1.6 | Monitoring the reaction conditions
Referring to the gathered information in hand from vari-
ous analyses, the claim of catalyst fabrication can be
proved. The feasibility of the suggested strategy and opti-
mizing reaction conditions were probed on the reaction
of benzaldehyde, aniline and TMSCN as a pattern reac-
tion. Furthermore, the nanocatalyst was assessed as a
powerful catalyst for synthesis of α‐aminonitrile deriva-
tives. To achieve the mentioned goal, the efficiency of
the introduced nanocatalyst was also compared with sev-
eral catalysts. The pattern reaction was carried out with
the best yield using Fe3O4@SiO2‐NH2‐GA as a catalyst
in comparison with gained catalysts from previous fabri-
cation levels (Table 1, entries 1–4; see also results of some
reported procedures for further comparison – entries 6–
3.1.7 | Investigation of catalyst activity
The obtained results provided an incentive to extend the
recommended process to various aromatic aldehyde sub-
strates. The corresponding α‐aminonitriles were obtained
in 85–98% yields (Table 2). Regarding the eco‐friendly
TABLE 2 GA‐grafted amine‐functionalized MNPs‐catalyzed synthesis of α‐aminonitriles
M.P. (°C)
Lit.
Entry
R1
R2
Product
Time (min)
Yielda (%)
Obs.
80–83
1
Phenyl
4‐Chlorophenyl
4‐Bromophenyl
3‐Nitrophenyl
H
H
4a
4b
4c
4d
4e
4f
10
10
5
98
97
98
94
92
98
93
92
97
88
90
90
98
95
87
89
88
95
85
91
98
98
96
91
98
73–75[40]
111–112[33]
100–101[40]
89–90[40]
91–92[40]
86–88[40]
124–125[40]
70–71[40]
99–101[34]
97–99[19]
2
113–115
102–106
84–88
3
H
4
H
10
15
5
5
4‐Methoxylphenyl
4‐Nitrophenyl
H
91–92
6
H
86–88
7
4‐Hydroxyphenyl
4‐Methylphenyl
4‐Fluorophenyl
2‐Thienyl–
H
4g
4h
4i
15
20
10
20
20
25
10
10
20
15
20
20
25
5
124–126
71–73
8
H
9
H
101–102
97–99
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
H
4j
2‐Furanyl
H
4k
4l
73–75
72–74[19]
4‐(Dimethylamino)phenyl
4‐Cyanophenyl
3,4,5‐Trimethoxyphenyl
4‐Hydroxy‐3‐methoxyphenyl
2‐Nitrophenyl
H
107–109
112–114
146–148
114–116
135–137
74–76
107–110[19]
113–115[35]
147–149[34]
113–115[31]
135–137[40]
75–78[19]
117–118[12]
69–70[35]
91–92[41]
105–107[35]
85–87[34]
103–106[34]
116–118[31]
83–85[19]
H
4m
4n
4o
4p
4q
4r
4s
H
H
H
2,6‐Dichlorophenyl
Cinnamaldehyde
2‐Chlorophenyl
3‐Fluorophenyl
Phenyl
H
H
121–123
69–71
H
H
4t
91–93
Me
Me
Me
Me
Me
4u
4v
4w
4x
4y
5
106–108
87–89
4‐Chlorophenyl
Cinnamaldehyde
4‐Methylphenyl
4‐Nitrophenyl
5
10
10
5
104–106
116–118
84–86
aIsolated yield.

6 of 7
MALEKI ET AL.
SCHEME 2 Proposed reaction cycle of
synthesis of α‐aminonitriles in the
presence of the nanocatalyst
aspects of the present work, including nanomagnetic het-
erogeneous catalyst (according to facile handling and
purify through an external magnet along with ease of
recoverable property), green solvent and room tempera-
ture conditions, the suggested protocol could be consid-
ered as environmentally friendly synthesis of α‐
aminonitriles.
different amines 2 in the presence of the catalyst. The fol-
lowing nucleophilic attack of TMSCN to imine yielded
the products 4a–y.
3.1.9 | Fe3O4@SiO2‐NH2‐GA reusability
Encouraged by the mentioned analyses results, the cata-
lyst reusability was also studied. Upon completion of the
pattern reaction (monitored by TLC), the catalyst was
separated using an external magnet. The recovered cata-
lyst was then added to a fresh reaction mixture under
identical conditions. The GA nanocatalyst could be effi-
ciently recovered up to eight times without suffering
any significant losses in its catalytic activity or the yield
of the model reaction (Figure 6). Also, the reaction was
repeated using acid‐washed catalyst and it was observed
that the reaction yield increased (entry 8). Therefore,
some deactivated hydroxyl groups of GA were activated
again by washing the catalyst with acid (HCl, 0.5 M).
3.1.8 | Mechanistic evaluation
A
proposed mechanism for the formation of α‐
aminonitrile derivatives is shown in Scheme 2. Through
activating the oxygen atom of the carbonyl by
Fe3O4@SiO2@NH2‐GA catalyst, intermediate
formed. In the case of iminium intermediate II, it is rea-
sonable to assume that it can be a consequence of the
condensation reaction between intermediate I and
I was
4 | CONCLUSIONS
A new facet of the synthesis and operational nano‐Fe3-
O4@SiO2‐NH2‐GA usage in achievements of the Strecker
reaction was accomplished in the present work. Further-
more, the most interesting features of the suggested pro-
cedure could be named as one‐pot MCR, excellent yield,
FIGURE 6 Recycling of the nanocatalyst for the model reaction

MALEKI ET AL.
7 of 7
[20] A. Maleki, E. Akhlaghi, R. Paydar, Appl. Organomet. Chem.
2016, 30, 382.
brief time period of reaction, green solvent, facile work‐
up procedure, ease of separation, and recyclability of the
magnetic catalyst.
[21] A. Maleki, R. Taheri‐Ledari, M. Soroushnejad, ChemistrySelect
2018, 3, 13 057.
[22] A. Maleki, Tetrahedron Lett. 2013, 54, 2055.
ACKNOWLEDGEMENTS
[23] C. Ó. Dálaigh, S. A. Corr, Y. Gun'ko, S. J. Connon, Angew.
Chem. 2007, 119, 4407.
The authors gratefully acknowledge the financial support
from the Research Council of the Iran University of Sci-
ence and Technology.
[24] A. Maleki, Ultrason. Sonochem. 2018, 40, 460.
[25] R. B. N. Baig, R. S. Varma, ACS Sustainable Chem. Eng. 2013, 1,
805.
[26] A. Schätz, M. Hager, O. Reiser, Adv. Funct. Mater. 2009, 19,
ORCID
2109.
[27] S. Verma, A. Singh, A. Mishra, Environ. Toxicol. Pharmacol.
2013, 35, 473.
Ali Maleki https://orcid.org/0000-0001-5490-3350
[28] M. Inoue, R. Suzuki, N. Sakaguchi, Z. Li, T. Takeda, Y. Oghara,
B. Y. Jiang, Y. Chen, Biol. Pharm. Bull. 1995, 18, 1526.
REFERENCES
[29] Y.‐Y. Ow, I. Stupans, Curr. Drug Metab. 2003, 4, 241.
[1] A. Maleki, J. Rahimi, O. M. Demchuk, A. Z. Wilczewska, R.
[30] L. A. Savi, P. C. Leal, T. O. Vieira, R. Rosso, R. J. Nunes, R. A.
Yunes, T. B. Creczynski‐Pasa, C. R. M. Barardi, C. M. O.
Simões, Arzneimittelforschung 2005, 55, 66.
Jasiński, Ultrason. Sonochem, 2018, 43, 262.
[2] M. Lounasmaa, J. Miettinen, P. Hanhinen, R. Jokela, Tetrahe-
dron Lett. 1997, 38, 1455.
[31] M. Eslami, M. G. Dekamin, L. Motlagh, A. Maleki, Green
Chem. Lett. Rev. 2018, 11, 36.
[3] A. D. S. Goes, C. Ferroud, J. Santamaria, Tetrahedron Lett.
1995, 36, 2235.
[32] A. Maleki, S. Azadegan, J. Inorg. Organomet. Polym. Mater.
2017, 27, 714.
[4] W. L. Matier, D. A. Owens, W. T. Comer, D. Deitchman, H. C.
Ferguson, R. J. Seidehamel, J. R. Young, J. Med. Chem. 1973,
16, 901.
[33] A. Maleki, H. Movahed, R. Paydar, RSC Adv. 2016, 6, 13 657.
[34] K. Niknam, D. Saberi, M. N. Sefat, Tetrahedron Lett. 2959, 2010,
[5] L. M. Weinstock, P. Davis, B. Handelsman, R. J. Tull, J. Org.
Chem. 1967, 32, 2823.
51.
[35] J. Wang, S. Zheng, Y. Shao, J. Liu, Z. Xu, D. Zhu, J. Colloid
Interface Sci. 2010, 349, 293.
[6] G. Dyker, Angew. Chem. Int. Ed. 1997, 36, 1700.
[7] S. K. De, R. A. Gibbs, Tetrahedron Lett. 2004, 45, 7407.
[8] A. Maleki, Tetrahedron. 2012, 68, 7827.
[36] M. N. Sefat, D. Saberi, K. Niknam, Catal. Lett. 2011, 141, 1713.
[37] M. A. Pasha, H. M. Nanjundaswamy, V. P. Jayashankara,
[9] Z.‐L. Shen, S.‐J. Ji, T.‐P. Loh, Tetrahedron 2008, 64, 8159.
[10] B. Karimi, A. Maleki, Chem. Commun. 2009, 5180.
Synth. Commun. 2007, 37, 4371.
[38] A. Nasreen, Tetrahedron Lett. 2013, 54, 3797.
[11] B. Karimi, A. Maleki, D. Elhamifar, J. H. Clark, A. J. Hunt,
[39] Y. Lu, Y. Wang, X. Zhang, J. Chem. Res. 2013, 37, 709.
Chem. Commun. 2010, 46, 6947.
[40] A. Maleki, R. F. Haji, M. Ghassemi, H. Ghafuri, J. Chem. Sci.
2017, 129, 457.
[12] A. Shaabani, A. Maleki, M. R. Soudi, H. Mofakham, Cat. Com.
2009, 10, 945.
[41] A. Mobaraki, B. Movassagh, B. Karimi, ACS Comb. Sci. 2014,
16, 352.
[13] A. Shaabani, A. Maleki, Appl. Catal. A 2007, 331, 149.
[14] A. Maleki, J. Rahimi, J. Porous Mat. 2018, 25, 1789.
[15] A. Maleki, V. Eskandarpour, J. Rahimi, N. Hamidi, Carbohydr.
Polym. 2019, 208, 251.
[16] A. Maleki, M. Niksefat, J. Rahimi, Z. Hajizadeh, BMC Chem-
istry. 2019, 13, 19.
How to cite this article: Maleki A, Azadegan S,
Rahimi J. Gallic acid grafted to amine‐
functionalized magnetic nanoparticles as a
proficient catalyst for environmentally friendly
synthesis of α‐aminonitriles. Appl Organometal
Chem. 2019;e4810. https://doi.org/10.1002/aoc.4810
[17] A. Maleki, N. Hamidi, S. Maleki, J. Rahimi, Appl. Organomet.
Chem. 2018, 32, e4245.
[18] M. Azizi, A. Maleki, F. Hakimpoor, R. Firouzi‐Haji, M.
Ghassemi, J. Rahimi, Lett. Org. Chem. 2018, 15, 753.
[19] A. Maleki, J. Rahimi, Z. Hajizadeh, M. Niksefat, J. Organomet.
Chem. 2019, 881, 58.