Application of [PVP-SO3H] HSO4 as an Efficient Polymeric-Based Solid Acid Catalyst in the Synthesis of Some Benzimidazole Derivatives

Full text of DOI:10.1080/00304948.2020.1765654

Organic Preparations and Procedures International
The New Journal for Organic Synthesis
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/uopp20
Application of [PVP-SO3H] HSO4 as an Efficient
Polymeric-Based Solid Acid Catalyst in the
Synthesis of Some Benzimidazole Derivatives
Fatemeh Pakpour Roudsari , Mohadeseh Seddighi , Farhad Shirini & Hassan
Tajik
To cite this article: Fatemeh Pakpour Roudsari , Mohadeseh Seddighi , Farhad Shirini & Hassan
Tajik (2020): Application of [PVP-SO3H] HSO4 as an Efficient Polymeric-Based Solid Acid Catalyst
in the Synthesis of Some Benzimidazole Derivatives, Organic Preparations and Procedures
International, DOI: 10.1080/00304948.2020.1765654
To link to this article: https://doi.org/10.1080/00304948.2020.1765654
Published online: 20 Jul 2020.
Submit your article to this journal
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at
https://www.tandfonline.com/action/journalInformation?journalCode=uopp20

ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
https://doi.org/10.1080/00304948.2020.1765654
EXPERIMENTAL PAPER
Application of [PVP-SO3H] HSO4 as an Efficient Polymeric-
Based Solid Acid Catalyst in the Synthesis of Some
Benzimidazole Derivatives
Fatemeh Pakpour Roudsari, Mohadeseh Seddighi, Farhad Shirini , and
Hassan Tajik
Department of Chemistry, College of Sciences, University of Guilan, Rasht, Iran
ARTICLE HISTORY Received 20 July 2019; Accepted 8 February 2020
Benzimidazoles, benzoxazoles and benzothiazoles are essential types of heterocyclic
compounds that are plentiful in nature. They have a wide spectrum of pharmacological
and biological activities such as anti-viral,1 anti-inflammatory,2 anti-hypertensive,3 anti-
microbial4 and antihistamine5 properties. Benzimidazoles display unique properties as
DNA minor-groove binding agents as well as ligands to transition metals.6–8 Clearly
this is an important structural element which can be found in many commercial medi-
cines (Fig. 1).
In general, there are two methods for the synthesis of benzimidazoles. The first
method involves the treatment of o-aminobenzenethiol, o-phenylenediamine and o-ami-
nophenol with carboxylic acids9 or their derivatives such as nitriles, imidates, or
orthoesters10–20 using a strong acidic catalyst. The second method, which leads to 2-
phenyl-1H-benzo[d]imidazoles, involves the two-step reaction of o-phenylenediamines
with aldehydes in the presence of appropriate reagents. Although it is known that these
reactions are accelerated with different catalysts,21–27 many of them occur in homoge-
neous conditions or have such problems as using high amounts of catalyst, high costs,
long reaction times, side products, severe reaction conditions or high oxidizing power.
The search for inexpensive, environmentally friendly, and non-homogeneous catalysts,
which can be easily separated and reused, is a major concern to heterocyclic chemists.
Heterogeneous solid acid catalysts are practical constituents in numerous industrial
€
processes. These types of catalysts have some advantages over homogeneous Bronsted
acid catalysts. These advantages include having: easy production and separation, higher
surface areas, lower costs and energy savings. Often they are non-toxic and non-corro-
sive, allow the reaction to be performed under under mild conditions and decrease the
number of reaction steps.28
€
The presence of Bronsted-acid functional groups (particularly SO3H and HSO4) within
the structures of solid acids, makes them useful for solvent-free conditions.29 [PVP-SO3H]
HSO4 is a polymeric-based solid acid catalyst (Fig. 2), that has been developed in our
research group and has been used in a number of significant reactions, including the syn-
thesis of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2H)-ones, 1-(benzothiazolylamino)
CONTACT Farhad Shirini
shirini@guilan.ac.ir
Department of Chemistry, College of Sciences, University of Guilan,
Rasht 41335, Iran
ß 2020 Taylor & Francis Group, LLC

2
F. P. ROUDSARI ET AL.
Figure 1. Structure of some of medicines containing the benzimidazole skeleton.
Figure 2. [PVP-SO3H] HSO4 as a polymeric-based solid acid catalyst.
phenylmethyl-2-naphthols, and 2H-indazolo[2,1-b]phthalazine-1,6,11(13H)-triones.30–32
Due to the specific benefits and structure of this catalyst, we decided to use it in the syn-
thesis of benzimidazole derivatives.
For the optimization of the conditions, the reaction between o-phenylenediamine and
triethyl orthoformate was chosen as the model in order to obtain 1 mmole of the prod-
uct, and the effects of different parameters such as amount of catalyst (Table 1, entries
1-3), temperature (Table 1, entries 4-6) and amount of triethyl-orthoformate (Table 1,
entries 7-9) were investigated. Regarding the results of Table 1, the best reaction condi-
tions in terms of time and efficiency were obtained with 1.5 mmol of triethyl orthofor-
mate, 7 mg [PVP-SO3H] HSO4 as the catalyst at 60ꢀ C under solvent-free conditions
(Scheme 1; Table 1, entry 2). It should be mentioned that this reaction did not take
place in the presence of solvent.
After determining the optimal conditions, a number of different derivatives of benzimida-
zoles, benzoxazoles and benzothiazoles were synthesized in the presence of [PVP-SO3H]
HSO4 using several orthoesters. As can be seen in Table 2, several o-phenylenediamine
derivatives (Table 2, entries 1-15) with electron-donating (H, CH3) and electron-withdraw-
ing (NO2) substituents on the aromatic ring were efficiently converted to the corresponding
substituted benzimidazoles in the presence of 4 mol% of [PVP-SO3H] HSO4 in a short time
and in very good yields. However, the electronic nature of the substituents showed some
effects on the conversion. In general, when using o-phenylenediamine with electron-donat-
ing groups, such as methyl groups, the desired products were obtained in short times
(Table 2, entries 1-6). In the presence of electron-withdrawing groups, such as nitro groups,

ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
3
Table 1. Optimization of the reaction conditions.
Entry
Catalyst (mg)
Orthoester (mmol)
Temperature (ꢀC)
Time (min.)
Yield (%)a
1
2
3
4
5
6
7
8
9
10
7
5
7
7
7
7
7
7
1.5
1.5
1.5
1.5
1.5
1.5
1
60
60
60
40
50
70
60
60
60
2
2
12
17
15
2
10
6
2
95
97
90
84
88
91
85
87
97
1.2
2
aIsolated yield.
Scheme 1. Synthesis of benzimidazoles, benzoxazoles and benzothiazoles in the presence of [PVP-
SO3H] HSO4.
longer reaction times or higher temperatures were needed for the completion of the reaction
(Table 2, entries 7-9). This catalyst successfully promoted the condensation of orthoesters
with o-aminophenol as well as o-aminothiophenol, leading to benzoxazoles and benzothia-
zoles respectively. Although the thiazole group gave the desired products at very short times
with excellent yields (Table 2, entries 13-15), the lower nucleophilicity of the OH group of
o-aminophenol necessitated higher temperature (Table 2, entries 10-12).
Encouraged by these results, we decided to use the catalyst in the preparation of 2-
phenyl-1H-benzo[d]imidazoles via condensation of o-phenylenediamines with alde-
hydes. For this purpose, the reaction between 4-chlorobenzaldehyde and 1,2-phenylene-
diamine was chosen as a model reaction to optimize the reaction conditions. Again, the
amount of the catalyst, temperature and solvent were investigated (Table 3).
The results showed that both solvent-free conditions and ethanol media could be uti-
lized for this preparation. Therefore, the further investigations were done in two ways
(Scheme 2): A) 1 mmol aldehyde, 1 mmol o-phenylenediamine and 20 mg [PVP-SO3H]
HSO4 under solvent-free conditions (Table 3, entry 4); and B) 1 mmol aldehyde, 1 mmol
o-phenylenediamine and 10 mg [PVP-SO3H] HSO4 in 2 mL EtOH at room temperature
(Table 3, entry 14).
According to the results in Table 4, different types of aldehydes which have electron-
donating and electron-withdrawing substituents produced the desired products with
high yields in suitable times. It is noteworthy that acid-sensitive groups such as methoxy
remain unchanged under the reaction conditions (Table 4, entries 11 and 12). Also, cin-
namaldehyde does not isomerize during the reaction and the product is obtained with a
yield of 96% (Table 4, entry 14). Under these conditions, 3-pyridine carbaldehyde, as an
example of a heterocyclic aldehyde, also gave us the required product in a short period

4
F. P. ROUDSARI ET AL.

ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
5

6
F. P. ROUDSARI ET AL.
Table 3. Optimization of reaction conditions for the synthesis of 2-phenyl-1H-benzo[d]imidazoles.
Entry
Catalyst (mg)
Solvent
Temperature (ꢀC)
Time (min.)
Yield (%)a
1
2
3
4
5
6
7
8
10
20
30
20
20
30
20
20
20
20
10
5
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
H2O
CH2Cl2
CH3CN
EtOH
EtOH
60
60
60
80
100
80
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
60
No Reaction
0
80
80
95
95
94
90
80
92
93
94
90
94
95
88
50
50
5
5
5
5
10
7
2
2
8
2
2
9
10
11
12
13
14
15
EtOH
EtOH
EtOH
EtOH
10
10
5
25
25
5
aIsolated yield.
Scheme 2. Synthesis using [PVP-SO3H] HSO4 in two ways.
of time (Table 4, entry 16). As can be seen from the data, the yields were uni-
formly good.
In order to indicate the potential of the procedures, some of the results obtained from
this study were compared with the relevant ones reported in the literature (Table 5).
Reduction of the reaction time, high yields of the products, reduction of the amount of
catalyst and temperature with high turn over frequency (TOF) are some of the advantages
of our new method.
The reusability of this catalyst was also checked. For this purpose, the reaction of 1,2-
phenylenediamine with triethyl orthoformate (Table 2, entry 1) and the reaction of 1,2-
phenylenediamine with 4-chlorobenzaldehyde (Table 4, entry 2) were investigated under
optimal conditions. These processes were repeated four and seven times respectively,
and performed well in all ways without major changes in reaction times and perform-
ance (Fig. 3). Furthermore, a comparison of the FT-IR spectrum of the fresh and recov-
ered catalyst shows that the nature of the catalyst remains largely unchanged (Fig. 4).
As a result, we have used [PVP-SO3H] HSO4 as an efficient polymeric-based solid
acid catalyst for the formation of the synthesis of benzimidazole, benzoxazole, and ben-
zothiazole derivatives. Ease of preparation and handling of the catalyst, chemoselectivity,
and an environmentally-friendly method are some of the important advantages of the
present method. Further work to explore this catalyst in other organic transformations
is in progress.
Experimental section
Chemicals were purchased from Fluka, Merck, and Aldrich chemical companies. All
yields refer to the isolated products. These products were characterized by comparison

ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
7

8
F. P. ROUDSARI ET AL.

ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
9

10
F. P. ROUDSARI ET AL.
Table 5. Comparison of the results obtained through acceleration by [PVP-SO3H] HSO4 with some
other methods.
(1c)
Yield
(%)a
(1d)
Yield
(%)a
Time
(min.)
TOF
(h-1)
Time
(min.)
TOF
(h-1)
Ref.
Catalyst (mol%)
Reaction conditions
6
Yb(OTf)3 (0.5)
Neat/90 ꢀC
HFIP/r.t.
60
150
–
40
92
–
90
95
93
91
80
0.04
–
77
23.75
9.3
60
150
12
15
30
150
4
92
90
80
89
93
93
93
184
0.04
400
15
Hexafluoroisopropanol (900)
17
Silica tungstic þacid (1)
Neat/80 ꢀC
TiO2-[bip]-NH2 HSO4 (10)18 Neat/90 ꢀC
7
36
–
19
Sulfamic acid (5)
CH3OH/r.t.
EtOH/r.t.
48
60
3
37.2
3.72
348.7
20
ZrCl4 (10)
[PVP-SO3H] HSO4 (4)
Neat/60 ꢀC
455
(2i)
(2k)
Ref.
Catalyst (mol%)
Reaction conditions
Time
(min.)
Yield
(%)a
TOF
(h-1)
Time
(min.)
Yield
(%)a
TOF
(h-1)
35
SASPSPE (3.4 mol%)
EtOH/Reflux
EtOH/Reflux
EtOH/Reflux
H2O/r.t.
EtOH/r.t.
H2O/r.t.
–
80
85
60
40
45
65
150
10
–
–
120
95
90
–
20
60
60
150
3
88
64
74
–
98
93
85
70
92
12.95
4.04
4.93
–
2.94
0.93
8.5
36
Nano-ZnO (10 mol%)
70
74
85
91
90
83
78
91
10.51
5.22
8.5
1.56
1.2
7.7
3.1
36
Nano-alumina (10 mol%)
37
[Hmim]TFA (10 mol%)
38
Fe(HSO4) (100 mol%)
38
Fe(HSO4) (100 mol%)
38
TiCl3OTf (10 mol%)
EtOH/r.t.
39
nano-Fe2O3 (10 mol%)
[PVP-SO3H] HSO4 (5.8 mol%)
H2O/80 ꢀC
EtOH/r.t.
2.8
317.24
94.13
aIsolated yield.
Figure 3. Reusability of [PVP-SO3H] HSO4 as the catalyst in the synthesis of benzimidazole (A) and 2-
(4-chlorophenyl)-1H-benzo[d]imidazole (B) derivatives.
of their physical constants, IR and nuclear magnetic resonance (NMR) spectroscopy
with authentic samples and those reported in the literature. The literature references are
provided in the Tables given above. The purity determination of the substrate and reac-
tion monitoring were done by thin layer chromatography (TLC) on silica gel Polygram
SILG/UV 254 plates, using the solvents specified below.

ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
11
Figure 4. FT-IR spectrum of the fresh and recovered catalyst.
General procedure for the preparation of benzimidazole, benzoxazole, and
benzothiazole derivatives
o-Phenylenediamine, o-aminophenol or o-aminothiophenol (1 mmol), ortho esters
(1.5 mmol) and [PVP-SO3H] HSO4 (7 mg, 4 mol %) were mixed and the resulting mix-
ture was stirred at 60 ꢀC for the appropriate time (Table 2). After completion of the
reaction, as indicated by TLC (EtOAc:n-hexane; 1:3), ethyl acetate (10 mL) was added
and the catalyst was separated by filtration. The organic phase was washed with water,
and then the organic phase was dried by Na2SO4. After filtration of the drying agent,
ethyl acetate was removed under reduced pressure to get the desired product. The spec-
tral data of representative compounds follow.
2-Methyl-6-nitro-benzimidazole (1i)
m.p. 225-226 ꢀC; IR (KBr) ꢀ ¼ 3105, 2996, 1629, 1591, 1521, 1428, 1333, 1123, 826,
1
738 cmꢁ1; H NMR (CDCl3, 400 MHz,): d ¼ 2.72 (3H, s, CH3), 7.60 (1H, d, J ¼ 8.8 Hz),
8.21 (1H, dd, J1 ¼ 8.8, J2 ¼ 2 Hz), 8.50 (1H, s) ppm.18
2-Methyl-benzothiazole (1o)
1
Oil; IR (KBr) ꢀ ¼ 3060, 2944, 1604, 1572, 1481, 1215, 703 cmꢁ1; H-NMR (CDCl3,
400 MHz,): d ¼ 2.83 (3H, s, CH3), 7.34 (1H, td, J1 ¼ 7.4 Hz, J2 ¼ 1.2 Hz), 7.44 (1H, td,

12
F. P. ROUDSARI ET AL.
J1 ¼ 7.8 Hz, J2 ¼ 1.2 Hz), 7.81 (1H, d, J ¼ 8.0 Hz), 7.96 (1H, d, J ¼ 8.0 Hz) ppm; 13C-
NMR (CDCl3, 100 MHz): d ¼ 20.1, 121.4, 122.4, 124.7, 125.9, 135.6, 153.3, 167.0 ppm.18
General procedure for the preparation of 2-phenyl-1H-benzo[d]imidazoles
o-Phenylenediamine (1 mmol), aldehyde (1 mmol) and [PVP-SO3H] HSO4 (10 mg,
5.8 mol %) were stirred in EtOH (10 mL) at room temperature or at 80 ꢀC under solvent
free conditions. The progress of the reaction was followed by TLC (EtOAc:n-hexane;
1:3). After the completion of the reaction EtOH (10 mL) was added and the catalyst was
separated by filtration. The crude product was recrystallized from ethanol to give the
pure product.
Typical preparation of benzimidazole (1a)
o-Phenylenediamine (0.108 g, 1mmol) was added to a mixture of triethyl orthoformate
(0.25 mL, 1.5 mmol) and [PVP-SO3H] HSO4 (7 mg, 4 mol %), and the resulting mixture
was stirred at 60 ꢀC for 2 min. Then, ethyl acetate (10 mL) was added and the catalyst
was separated by filtration. The organic phase was washed with water, and then the
organic phase was dried by Na2SO4. After removal of the drying agent by filtration,
ethyl acetate was removed under reduced pressure to get the benzimidazole (1a)
as product.
Typical preparation of 2-(4-chlorophenyl)-1H-benzo[d]imidazole (2b):
Method A: 4-Chlorobenzaldehyde (0.14 g, 1 mmol), o-phenylenediamine (0.108 g,
1 mmol) and [PVP-SO3H] HSO4 (10 mg, 5.8 mol%) were stirred in EtOH (10 mL) at
room temperature for 2 min. After the completion of the reaction, the reaction mixture
was heated to dissolve the product in EtOH. Then, the catalyst was separated by filtra-
tion. The crude product separated out and was recrystallized from ethanol to give 2-(4-
chlorophenyl)-1H-benzo[d]imidazole (2b) as pure product. Method B: 4-
Chlorobenzaldehyde (0.14 g, 1 mmol), o-phenylenediamine (0.108 g, 1mmol) and [PVP-
SO3H] HSO4 (10 mg, 5.8 mol %) were stirred solvent-free at 80 ꢀC for 5 min. Then,
EtOH (10 mL) was added and the catalyst was separated by filtration Note: the product
is soluble in hot ethanol while the catalyst is insoluble. Upon cooling, the crude product
separated out and the solid product was recrystallized from ethanol to give 2-(4-chloro-
phenyl)-1H-benzo[d]imidazole (2b).
Acknowledgment
The financial support of this work by the Research Council of the University of Guilan is
acknowledged.
ORCID
Farhad Shirini
http://orcid.org/0000-0002-7204-5000

ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
13
References
1. G. L. Gravatt, B. C. Baguley, W. R. Wilson and W. A. Denny, J. Med. Chem., 37, 4338
(1994). doi:10.1021/jm00051a010
2. J. S. Kim, B. Gatto, C. Yu, A. Liu, L. F. Liu and E. J. La Voie, J. Med. Chem., 39, 992 (1996).
doi:10.1021/jm950412w
3. T. Roth, M. L. Morningstar, P. L. Boyer, S. H. Hughes, R. W. J. Buckheit and C. J. Michejda,
J. Med. Chem., 40, 4199 (1997). doi:10.1021/jm970096g
4. K. F. Ansari and C. Lal, Eur. J. Med. Chem., 44, 4028 (2009). doi:10.1016/j.ejmech.2009.04.
037
5. S. N. Lin and L. H. Yang, Tetrahedron Lett., 46, 4315 (2005). doi:10.1016/j.tetlet.2005.04.101
6. L. Wang, J. Sheng, H. Tian, and C. Qian, Synth. Commun., 34, 4265 (2004). doi:10.1081/
SCC-200039340
7. F. A. Tanious, D. Hamelberg, C. Bailly, A. Czarny, D. W. Boykin and W. D. Wilson, J. Am.
Chem. Soc., 126, 143 (2004). doi:10.1021/ja030403þ
8. T. Fekner, J. Gallucci and M. K. Chan, J. Am. Chem. Soc., 126, 223 (2004). doi:10.1021/
ja030196d
9. J. B. Wright, Chem. Rev., 48, 397(1951). doi:10.1021/cr60151a002
10. S. I. Alaqeel, J. Saudi Chem. Soc., 21, 229 (2017). doi:10.1016/j.jscs.2016.08.001
11. M. Mazloumi, F. Shirini, O. G. Jolodar and M. Seddighi, J. Chem., 42, 5742 (2018). doi:10.
1039/C8NJ00171E
12. Y.-N. Wang, R. R. Y. Bheemanaboina, G.-X. Cai and C.-H. Zhou, Bio. Med. Chem. Lett., 28,
1621 (2018). doi:10.1016/j.bmcl.2018.03.046
13. K. Nikoofar and S. M. Dizgarani, Iran. Chem. Commun., 6, 62 (2018).
14. M. Jyothi and R. Merugu, Asian J. Pharm. Clin. Res., 10, 48 (2017). doi:10.22159/ajpcr.2017.
v10i10.19457
15. S. Khaksar, A. Heydari, M. Tajbakhsh, and S. M Vahdat, J. Fluorine Chem., 131, 1377
(2010). doi:10.1016/j.jfluchem.2010.10.002
16. C. T. Brain and J. T. Steer, J. Org. Chem., 68, 6814 (2003). doi:10.1021/jo034824l
17. B. Karami, S. Nikoseresht and S. Khodabakhshi, Chin. J. Catal., 33, 298 (2012). doi:10.1016/
S1872-2067(11)60329-X
18. M. Mazloumi, F. Shirini, O. Goli-Jolodar, and M. Seddighi, New. J. Chem., 42, 5742 (2018).
doi:10.1039/C8NJ00171E
19. Z. Zhang, T. Li and J. Li, Monatsh. Chem., 138, 89 (2007). doi:10.1007/s00706-006-0566-1
20. Z. Zhang, L. Yin and Y. Wang. Catal. Commun., 8, 1126 (2007). doi:10.1016/j.catcom.2006.
10.022
21. L. H. Du and Y. G. Wang, Synthesis 5, 675 (2007). doi:10.1055/s-2007-965922
22. R. Jadhav, M. U. Shaikh, R. P. Kale, and C. H. Gill, Chin. Chem. Lett., 20, 292 (2009). doi:10.
1016/j.cclet.2008.09.057
23. N. Iravani, N. S. Mohammadzade and K. Niknam, Chin. Chem. Lett., 22, 1151 (2011).
24. M. A. Chari, D. Shobha and T. Sasaki, Tetrahedron Lett., 52, 5575 (2011). doi:10.1016/j.tetlet.
2011.08.047
25. L. S. Gadekar, B. R. Arbad and M. K. Lande, Chin. Chem. Lett., 21, 1053 (2010). doi:10.1016/
j.cclet.2010.03.038
26. R. Trivedi, S. K. De and R. A. Gibbs, J. Mol. Cat. A: Chem., 245, 8 (2005).
27. H. M. Bachhav, S. B. Bhagat and V. N. Telvekar, Tetrahedron Lett., 52, 5697 (2011). doi:10.
1016/j.tetlet.2011.08.105
28. G. Brahmachari and S. Laskar, Tetrahedron Lett., 51, 2319 (2010). doi:10.1016/j.tetlet.2010.02.
119
29. P. Wasserscheid, M. Sesing and W. Korth, Green Chem., 4, 134 (2002). doi:10.1039/b109845b
30. O. G. Jolodar, F. Shirini and M. Seddighi, RSC Adv., 6, 44794 (2016). doi:10.1039/
C6RA08486A
31. F. Shirini, P. N. Moghadam, S. Moayedi and M. Seddighi, RSC Adv., 4, 38581 (2014). doi:10.
1039/C4RA04915B

14
F. P. ROUDSARI ET AL.
32. M. Shamsi-Sani, F. Shirini, M. Abedini and M. Seddighi, Res. Chem. Intermed., 42, 1091
(2016). doi:10.1007/s11164-015-2075-5
33. H. Eshghi, M. Rahimizadeh, A. Shiri and P. Sedaghat, Bull. Korean Chem. Soc., 33, 515
(2012). doi:10.5012/bkcs.2012.33.2.515
34. F. Shirini, M. Abedini, M. Seddighi and F. S. Arbosara, Res. Chem. Intermed., 41, 7683
(2015). doi:10.1007/s11164-014-1852-x
35. S. Tayebi, M. Baghernejad, D. Saberi and K. Niknam, Chin. J. Catal., 32, 1477 (2011). doi:10.
1016/S1872-2067(10)60260-4
36. A. Teimouri, A. N. Chermahini, H. Salavati and L. Ghorbanian, J. Mol. Catal. A: Chem., 373,
38 (2013). doi:10.1016/j.molcata.2013.02.030
37. M. Dabiri, P. Salehi, M. Baghbanzadeh, M. Shakouri Nikcheh, Synth. Commun., 38, 4272
(2008). doi:10.1080/00397910802326539
38. J. Azizian, P. Torabi and J. Noei, Tetrahedron Lett., 57, 185 (2016). doi:10.1016/j.tetlet.2015.
11.092
39. D. Kommula and S. R. M. Madugula, J. Iran. Chem. Soc., 14, 1665 (2017) doi:10.1007/
s13738-017-1107-z