Synthesis and biological evaluation of 1,2,4,5-tetrasubstituted imidazoles

Article abstract of DOI:10.1007/s11164-017-2886-7

Tetrasubstituted imidazoles were synthesized in high yields via the four-component reaction of aromatic aldehydes, amines, substituted benzils and ammonium acetate catalyzed by a porous CeO₂ nanorod. Their anti-cancer activities on the Huh-7 hepatocellular carcinoma cell and antibacterial activities on four bacterial species (wild-type Escherichia coli, wild-type Staphylococcus aureus, Pseudomonas aeruginosa PAM1032 and Escherichia coli-NMD-1) in vitro were evaluated. One compound (5p) was screened out because of its high inhibition rate on all four bacterials at 100 μg/mL. Three products (5p, 5t and 5y) showed a high inhibition rate on the Huh-7 hepatocellular carcinoma cell at 10 μg/mL. The results indicated their potential in new drug development.

Full text of DOI:10.1007/s11164-017-2886-7

Res Chem Intermed
DOI 10.1007/s11164-017-2886-7
Synthesis and biological evaluation of 1,2,4,5-
tetrasubstituted imidazoles
Yue Fang1 Rui Yuan1 Wen-hui Ge1
•
•
•
Yuan-jiang Wang1 Gui-xiang Liu1
•
•
Ming-qi Li1 Jiang-biao Xu1 Yu Wan2
•
•
•
Sheng-liang Zhou2 Xi-guang Han1
•
•
Peng Zhang2 Jin-juan Liu2 Hui Wu1,2
•
•
Received: 21 October 2016 / Accepted: 2 February 2017
Ó Springer Science+Business Media Dordrecht 2017
Abstract Tetrasubstituted imidazoles were synthesized in high yields via the four-
component reaction of aromatic aldehydes, amines, substituted benzils and
ammonium acetate catalyzed by a porous CeO2 nanorod. Their anti-cancer activities
on the Huh-7 hepatocellular carcinoma cell and antibacterial activities on four
bacterial species (wild-type Escherichia coli, wild-type Staphylococcus aureus,
Pseudomonas aeruginosa PAM1032 and Escherichia coli-NMD-1) in vitro were
evaluated. One compound (5p) was screened out because of its high inhibition rate
on all four bacterials at 100 lg/mL. Three products (5p, 5t and 5y) showed a high
inhibition rate on the Huh-7 hepatocellular carcinoma cell at 10 lg/mL. The results
indicated their potential in new drug development.
Keywords Tetrasubstituted imidazoles Á Porous CeO2 Nanorod Á Synthesis Á
Bioactivity
Introduction
Imidazole and its derivatives are important heterocyclic compounds present in many
natural products and important drugs (Fig. 1). Compounds bearing an imidazole
framework possess significant pharmacological and biological activities such as
Electronic supplementary material The online version of this article (doi:10.1007/s11164-017-2886-7)
contains supplementary material, which is available to authorized users.
&
Hui Wu
6020030010@jsnu.edu.cn
1
2
School of Chemistry and Chemical Engineering, Jiangsu Normal University,
Xuzhou 221116, People’s Republic of China
State Key Laboratory Cultivation Construction Base of Biotechnology on Med-edible Plant of
Jiangsu Province, Jiangsu Normal University, Xuzhou 221116, People’s Republic of China
123

Y. Fang et al.
Fig. 1 Examples of imidazole-containing drugs
antiviral, anticytokine [1], anti-inflammatory [2], anti-allergic, analgesic activities,
sterilization [3], etc. For example, 4,5-disubstituted imidazoles have been used as
inhibitors of the P38 MAP kinase [4]. Moreover, imidazole derivatives can be used
as plant growth regulators [5], herbicides and pesticides [6]. The imidazole moiety
can also be applied in some important ligands [7] and photophysical areas such as
organic electroluminescent devices (OLED) [8, 9].
Much effort has been made to synthesize imidazoles with various functional
groups such as with the Debus synthesis [10], Radiszewski synthesis [11],
dehydrogenation of imidazolines [12], Wallach synthesis [13] and Marckwald
synthesis [14], etc. Various catalysts such as ZrCl4 [15], FeCl3Á6H2O [16],
InCl3Á3H2O [17], zeolite, [18] NaHSO3, [19] heteropoly acids, [20] sulfonated
amino acid [21], iodine, [22] oxalic acid [23], ionic liquid [24], BrØnsted acidic
ionic liquids [25], silica gel/NaHSO4 [26], K5CoW12O40Á3H2O [27], HClO4-SiO2
[28], acetic acid [29], H6P2W18O62Á24H2O/SiO2 [30], MCM-41 or p-TsOH [31]
were used. In addition, 1,2,4,5-tetrasubstituted imidazoles can also be obtained
through the hetero-Cope rearrangement or the N-alkylation of trisubstituted
imidazoles [32].
However, the range of substrate and yield are limited by many obstacles, such as
generation of significant amounts of waste materials, occurrence of side reactions,
complex work-up and purification. [29] Only a few methods are efficient [20].
Therefore, developing simple, efficient and green catalysts for synthesis of
imidazole derivatives is still appealing to scientists. In 2012, Chakrabortithe’s
group first reported the unaddressed issue of competitive formation of tri- and tetra-
substituted imidazole and highlighted the influence of the catalyst systems in
controlling the selective formation of tetra substituted imidazole [33].
Due to the large controllable pore sizes and big specific surface areas, the
application of nanoparticles as catalysts has drawn considerable attention in organic
synthesis recently [34–36]. Nanoparticle catalysts have been developed to promote
several common reactions, including hydrogenation, oxidation, [37, 38] C–C
coupling, [39–42] the synthesis of nitrogen-containing heterocycles, [43–45]
hydroformylation [46], olefin metathesis [47], epoxidation [48] and azoarene
formation [49], etc.
123

Synthesis and biological evaluation of 1,2,4,5-…
Herein, the synthesis of 1,2,4,5-tetrasubstituted imidazoles with high yields via
four-component reaction of aromatic aldehydes, primary amines, benzils and
ammonium acetate catalyzed by porous CeO2 nanorod was reported first
Scheme 1 Synthesis of tetrasubstituted imidazoles
Table 1 Conditions of optimization based on the synthesis of 5a
Entry
Cat.
X (mol%)
Solvent
T (°C)
t (h)
Yield (%)b
1
N-CeOa2
N-CeOa2
N-CeOa2
N-CeOa2
N-CeOa2
Powder CeO2
–
N-CeOa2
N-CeOa2
N-CeOa2
N-CeOa2
N-CeOa2
N-CeOa2
N-CeOa2
N-CeOa2
N-CeOa2
N-CeOa2
N-CeOa2
N-CeOa2
N-CeOa2
1
1
1
1
1
5
–
1
2
3
5
10
5
5
5
5
5
5
5
5
CH3CN
C2H5OH
H2O
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
40
6
6
75
76
50
54
86
Nrc
Nrc
50
75
76
88
89
56
Nrc
Nrc
65
77
82
88
89
2
3
6
4
THF
6
5
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
6
6
6
7
6
8
6
9
6
10
11
12
13
14
15
16
17
18
19
20
a
6
6
6
6
rt
6
0
6
Reflux
Reflux
Reflux
Reflux
Reflux
1
2
3
12
16
Nano CeO2
b
c
Isolated yields
Nr no reaction
123

Y. Fang et al.
Yield (%)a
Table 2 Synthesis of 5 under
optimum conditions
Entry R1
R2
R3
R4
5a
5b
5c
5d
5e
5f
4-OCH3
4-Cl
C6H5
C6H5
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
88
90
80
86
87
82
85
87
83
86
89
86
85
82
89
90
90
89
88
91
89
92
91
87
93
90
3,4,5-(OCH3)3 C6H5
H
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
CH3
4-NO2
4-Br
4-I
5g
5h
5i
3-F
3-Br
4-F
5j
5k
5l
3-NO2
2-Br
2-OCH3
4-CN
4-OCH3
4-Cl
5m
5n
5o
5p
5q
5r
5s
CH3
3,4,5-(OCH3)3 CH3
4-NO2
4-I
CH3
CH3
5t
3-F
CH3
5u
5v
5w
5x
5y
5z
5aa
3-NO2
2-Br
CH3
Reaction conditions: aldehyde 1
(1 mmol), amine 2 (1 mmol),
ammomium acetate 3
(1.5 mmol), benzil derivatives 4
(1 mmol), nanoparticle CeO2
(5 mol %) and CH3OH (10 mL)
heating under reflux for 12 h
CH3
2-OCH3
4-CN
2-F-4-Br
4-OCH3
2-Br
CH
CH3
CH3
4-ClC6H4
C6H5
2-Cl 3,4-OCH3 86
a
Isolated yields
(Scheme 1). The anti-cancer activity on Huh-7 hepatocellular carcinoma cells and
antibacterial activities on four bacterial species (wild-type Escherichia coli, wild-
type Staphylococcus aureus, Pseudomonas aeruginosa PAM1032 and Escherichia
coli-NMD-1) of the products was evaluated.
Results and discussion
The reaction conditions were optimized first based on the synthesis of 5a. As shown
in Table 1, methanol was more efficient than water and other organic solvents such
as EtOH, CH3CN and THF (Entries 1–5), which may be due to its proper polarity
and good dissolving ability of substrates. It is apparent that the reaction could not be
carried out without catalyst (Entry 7) or using 5 mol% of powder CeO2 as catalyst
(Entry 6). However, when 3 mol% of porous CeO2 nanorod was added, 76% of 5a
123

Synthesis and biological evaluation of 1,2,4,5-…
Scheme 2 A supposed mechanism
was obtained (Entry 10). Increasing porous CeO2 nanorod to 5 mol% led to an
increasing yield of 5a to 88% (Table 1, Entry 11), which indicated the load of
catalyst was the key point to improving yield. However, further increasing the
catalyst to 10 mol% did not raise the yield observably (Table 1, Entry 12, 89%).
The optimum temperature was the boiling point of MeOH (Table 1, Entries 13–15).
The optimum reaction time was 12 h (Table 1, Entries 16–20). With the optimized
conditions in hand, we proceeded to explore the substrate’s scope (Table 2). The
results showed that the reactions were equally facile with both electron-donating
and electron-withdrawing substituents present on the aromatic aldehydes, amines
and benzils and resulted in high yields of the corresponding imidazoles. Moreover,
the position of substituents in aromatic aldehydes, amines and benzils had also no
obvious influence on the yield.
A possible mechanism was proposed in Scheme 2 based on the literature
[50, 51]. Firstly, the carbonyl group in aldehyde had undergone protonation, and the
intermediate reacted with ammonia which was generated from NH4OAc. After
reacting with the aniline, intermediate (A) is formed. In the presence of a porous
CeO2 nanorod, intermediate (B) condensed with benzyl, and intermediate (C) was
formed. Subsequently, intermediate (C) was dehydrated, and finally, tetrasubstituted
imidazoles were obtained.
123

Y. Fang et al.
Table 3 Inhibition rate of 5 on
Escherichia coli and
Compound (lg/mL) Escherichia coli
Staphylococcus aureus
Staphylococcus aureus (lg/mL)
1
10
100
1
10
100
5a
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
36.2
–
–
38.3
40.0
43.0
44.1
–
–
5b
–
–
–
5c
–
–
–
5d
–
–
–
5e
–
31.2
–
–
–
5f
–
57.2
–
–
5g
–
–
–
5h
–
–
–
–
5j
–
–
–
–
5j
–
–
53.0
40.9
51.8
37.8
38.7
36.2
–
–
5k
–
–
–
5l
–
30.1
–
–
5m
5n
–
–
–
–
–
5o
–
–
–
5p
100.0
–
100.0
–
5q
–
–
40.0
–
5r
–
–
–
5s
–
–
35.9
–
–
5t
–
–
–
5u
58.4
–
–
–
–
5v
–
64.3
35.2
30.2
91.5
38.9
50.5
75.1
–
5w
5x
–
–
–
–
–
–
5y
–
36.8
–
–
5z
–
–
5aa
AP
KAN
Meropenem
–
44.3
–
–
62.7 61.9
99.8
94.2 99.0 100.0 99.8
100.0 98.2
Data less than 30% was showed
as ‘‘–’’
96.2 97.7 100.0 100.0 100.0 100.0
In the reaction, the key role of a porous CeO2 nanorod was also discussed
preliminarily. The porous CeO2 nanorods may act as a microreactor with the ability
to drive the reaction on the pore surfaces. Combined with the hydrophobic
aggregation of solvent, which effectively gathered the organic reagents at the
surface of the heterogeneous catalyst and allowed them to enter the pores, these
properties allowed organic molecules in the microreactor to react with each other
readily and efficiently.
The antibacterial activities of four bacterial species (Escherichia coli (wild-type),
Staphylococcus aureus (wild-type), Pseudomonas aeruginosa (PAM1032) and
Escherichia coli containing the NDM-1 drug-resistant genes (Escherichia coli-
123

Synthesis and biological evaluation of 1,2,4,5-…
Table 4 Inhibition rate of 5 on Pseudomonas aeruginosa and Escherichia coli-NMD-1 (lg/mL)
Compound (lg/mL)
Pseudomonas aeruginosa
Escherichia coli-NMD-1
1
10
100
1
10
100
5p
–
–
–
–
–
–
–
–
47.0
–
–
–
100.0
–
AP
–
–
KAN
Meropenem
100.0
37.1
99.6
–
100.0
100.0
100.0
100.0
Data of 5a–5o, 5q–5z and 5aa were less than 30%
Table 5 Inhibition rate of 5 on
Huh-7 hepatocellular carcinoma
cell
Compound Inhibition rate (%) Compound Inhibition rate (%)
5a
5b
5c
5d
5e
5f
–
5o
5p
5q
5r
5s
–
–
87.3
61.9
–
42.5
44.3
–
–
–
5t
74.3
42.0
34.6
–
5g
5h
5i
–
5u
5v
5w
5x
5y
5z
5aa
–
–
35.9
39.4
–
5j
–
5k
5l
79.8
–
63.0
32.3
40.3
5m
5n
–
Data less than 30% was showed
as ‘‘–’’
–
NMD-1)), and anti-cancer activities on the Huh-7 hepatocellular carcinoma cell line
of products were subsequently tested.
In the determination of antibacterial activities, the stock solution (10 mg/mL) of
every product was prepared by dissolving a relative compound in DMSO. The
solution was diluted to 1, 10 or 100 lg/mL, respectively, with DMSO to giving the
working solution. The same concentration (1, 10 or 100 lg/mL, respectively) of
ampicillin (AP), kanamycin (KAN) and meropenem were used as the controls. The
results are shown in Tables 3 and 4.
The results in Tables 3 and 4 indicate that product 5 could only inhibit
Staphylococcus aureus (wild-type) in 10 lg/mL, and the reason needs further
research in detail. Compound 5p showed a high inhibition rate on all four bacterial
species at 100 lg/mL. It was worth noting that the inhibition of 5p on Pseudomonas
aeruginosa and Escherichia coli-NMD-1 (containing the NDM-1 resistance genes)
were superior to AP, which showed its high research value for the future.
123

Y. Fang et al.
Subsequently, the antitumor activity on the Huh-7 hepatocellular carcinoma cell
line by the CCK-8 of products was tested (Table 5). The 10 lg/mL of working
solutions in DMSO were formulated. The strains fluid was cultivated in a
thermostatic 37 °C for 48 h, by measuring the absorbance changes before and after
the cultivation, then calculating the inhibition rate of these compounds. From
Table 5, the inhibition rate of half of 5 on Huh-7 cell exceeded 30% and 5p (87.3%)
worked best while 5y (79.8%) and 5t (74.3%) possessed second and third
inhibitions, respectively. It seems that electro-withdrawing R1 was superior to the
electro-donating ones. The electro effect and position of other substituent R2, R3 and
R4 had no previous influence on the inhibition rate.
Conclusions
In this study, we introduced a simple and novel porous CeO2 nanorod-catalyzed
methodology for the synthesis of 1,2,4,5-tetrasubstituted imidazoles from one-pot,
four-component reaction of benzils with aldehyde, amine and ammonium acetate.
Their results of antibacterial and anti-cancer activities on four bacterial and Huh-7
hepatocellular carcinoma cell, respectively, showed (5p) has a high inhibition rate
on all four bacterial species at 100 lg/mL, and three products (5p, 5t and 5y)
showed a high inhibition rate on the Huh-7 hepatocellular carcinoma cell line at 10
lg/mL. The results indicate their potential in drug development.
Acknowledgements We are grateful to the foundation of the ‘‘National Natural Sciences Foundation of
China’’ (No. 21201088, 31300067), ‘‘Priority Academic Program Development of Jiangsu Higher
Education Institutions’’, ‘‘Major Project of Natural Science Research of University in Jiangsu’’ (No.
14KJA430003, 15KJA180002), ‘‘Aid project for PhD faculties in Jiangsu Normal University’’
(13XLR007), and ‘‘Science and Technology Planning Project of Xuzhou’’ (KC15SH080) for financial
support.
References
1. Y. Saima, S. Kharmarui, K.S. Gayen, P. Pandit, D.K. Maiti, Chem. Commun. 48, 6601 (2012)
2. M. Misono, Chem. Commun. 13, 1141 (2006)
3. U. Ucucu, N.G. Karaburun, I. Iskdag, II Farmaco. 56, 285 (2001)
4. J.A. Murry, Curr. Opin. Drug Disc. 6(6), 945 (2003)
5. H. Veisi, A. Khazaei, L. Heshmati, S. Hemmati, Kor. Chem. Soc. 33(4), 1231 (2012)
6. I. Yavari, E. Kowsari, Mol. Divers. 13(4), 519 (2009)
7. H. Konishi, T. Ueda, T. Muto, K. Manabe, Org. Lett. 14, 4722 (2012)
8. A.P. Kulkarni, C.J. Tonzola, A. Babel, S.A. Jenekhe, Chem. Mater. 16, 4556 (2004)
9. P. Wu, J.P. Qu, Y.X. Li, X. Guo, D. Tang, X. Meng, R.L. Yan, B.H. Chen, Adv. Synth. Catal.
357(18), 3868 (2015)
10. H. Debus, Liebigs Ann. Chem. 107(2), 199 (1858)
11. E. Lunt, C.G. Newton, C. Smith, G.P. Stevens, M.F. Stevens, C.G. Straw, R.J. Walsh, F. Lavelle, J.
Med. Chem. 30(2), 357 (1987)
12. R. C. Elderfield, Heterocyclic compounds. 744 (Wiley, 1957)
13. Wallach & Schuelze. Ber. 14, 420(1881)
14. A. Bhatnagar, P.K. Sharma, N. Kumar, Int. J. Phamrm Tech Res. 3(1), 268 (2011)
15. G. Sharma, Y. Jyothi, P. Lakshmi, Synthetic. Commun. 36(20), 2991 (2006)
16. M.M. Heravi, F. Derikvand, M. Haghighi, Monatsh. Chem. 139, 31 (2008)
123

Synthesis and biological evaluation of 1,2,4,5-…
17. S.D. Sharma, P. Hazarika, D. Konwar, Tetrahedron Lett. 49, 2216 (2008)
18. S. Balalaie, A. Arabanian, M. Hashtroudi, Monatsh. Chem. 131(9), 945 (2000)
19. J. Sangshetti, N. Kokare, A. Kotharkar, D. Shinde, Monatsh. Chem. 139(2), 125 (2008)
20. M.M. Heravi, F. Derikvand, F.F. Bamoharram, J. Mol. Catal. A-Chem. 263, 112 (2007)
21. A. Mohammed, N. Kokare, J. Sangshetti, D. Shinde, Kor. Chem. Soc. 51(5), 418 (2007)
22. M. Kidwai, P. Mothsra, V. Bansal, R. Goyal, Monatsh. Chem. 137(9), 1189 (2006)
23. N.D. Kokare, J.N. Sangshetti, D.B. Shinde, Synthesis 18, 2829 (2007)
24. H.R. Shaterian, M.J. Ranjbar, J. Mol. Liq. 160, 40 (2011)
25. A. Davoodnia, M.M. Heravi, Z. Safavi-Rad, N. TavakoliHoseini, Synthetic. Commun. 40, 2588
(2010)
26. A.R. Karimi, Z. Alimohammadi, J. Azizan, A.A. Mohammadi, R.R. Mohmmadizadeh, Catal.
Commun. 7(9), 728 (2006)
27. L. Nagarapu, S. Apuri, S. Kantevari, J. Mol. Catal. A-Chem. 266, 104 (2007)
28. S. Kantevari, S.V.N. Vuppalapati, D.O. Birdar, L. Nagarapu, J. Mol. Catal. A-Chem 271, 266 (2007)
29. J.F. Zhou, Y.Z. Song, Y.L. Zhu, S.J. Tu, Synth. Commun. 35(10), 1369 (2005)
30. A.R. Karimi, Z. Alimohammadi, M.M. Amini, Mol. Divers. 14, 635 (2010)
31. R. Hekmat, G. Shoar, F. Rahimzadeh, M. Derikvand, Farzaneh. Synth. Commun. 40, 1270 (2010)
32. A. Emrani, A. Davoodnia, N.B. Tavakoli-Hoseini, Kor. Chem. Soc. 32, 2385 (2011)
33. K. Dinesh, D.N. Kommi, A.R. Patel, A.K. Chakraborti, Green Chem. 14, 2038 (2012)
34. V.P. Reddy, A.V. Kumar, K. Swapna, R.K. Rao, Org. Lett. 11, 1697 (2009)
35. M.Z. Kassaee, Chem. Lett. 22, 1203 (2011)
36. S. Santra, A. Majee, A. Hajra, Tetrahedron Lett. 53, 1974 (2012)
37. M. Kotani, T. Koike, K. Yamaguchi, Green Chem. 8, 735 (2006)
38. R.L. Oliveria, P.K. Kiyohara, M. Rossi, Green Chem. 12, 144 (2010)
39. O. Baudoin, M. Cesario, D. Guenard, J. Org. Chem. 67, 1199 (2002)
40. Y. Zheng, P.D. Stevens, Y. Gao, J. Org. Chem. 71, 537 (2006)
41. U. Laska, C.G. Frost, J. Price, J. Catal. 268, 318 (2009)
42. K. Seth, P. Purohit, A.K. Chakraborti, Org. Lett. 16, 2334 (2014)
43. V. Polshettiwar, B. Baruwati, R.S. Varma, Chem. Commun. 36, 1837 (2009)
44. V. Polshettiwar, R.S. Varma, Tetrahedron 66, 1091 (2010)
45. K. Seth, S.R. Roy, A.K. Chakraborti, Chem. Commun. 52, 922 (2016)
46. R. Abu-Reziq, H. Alper, D. Wang, J. Am. Chem. Soc. 128, 5279 (2006)
47. C. Che, W. Li, S. Lin, Chem. Commun. 67, 5990 (2009)
48. S. Shylesh, J. Schweizer, S. Demeshko, Adv. Synth. Catal. 351, 1789 (2009)
49. K. Seth, S.R. Roy, A. Kumar, A.S. Chakraborti, Catal. Sci. Technol. 6, 2893 (2016)
50. E. Mohsen, J. Jaber, Z. Maryam, New. J. Chem. doi:10.1039/C5NJ00050E
51. K.F. Shelke, S.B. Sapkal, S.S. Sonar, B.R. Madje, B.B. Shingate, M.S. Shingate, Bull. Korean Chem.
Soc. 30, 1057 (2009)
123