Facile and efficient synthesis of tetrahydrobenzimidazo [2,1-b]quinazolin-1(2h)-one derivatives using br?nsted acidic ionic liquid immobilized on nanoporous Na+-montmorillonite

Article abstract of DOI:10.1166/jnn.2018.13954

In this work, an efficient and green procedure have been described for the synthesis of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2H-one derivatives using nanoporous sodium montmorillonite clay (Na⁺-MMT) modified with 1-methyl-3-(trimethoxysilyl

Full text of DOI:10.1166/jnn.2018.13954

Article
Journal of
Nanoscience and Nanotechnology
Vol. 18, 1194–1198, 2018
Copyright © 2018 American Scientific Publishers
All rights reserved
www.aspbs.com/jnn
Printed in the United States of America
Facile and Efficient Synthesis of Tetrahydrobenzimidazo
[2,1-b]Quinazolin-1(2H)-One Derivatives Using
Brönsted Acidic Ionic Liquid Immobilized on
Nanoporous Na+-Montmorillonite
Farhad Shirini∗, Masoumeh Mazloumi, and Mohadeseh Seddighi
Department of Chemistry, College of Science, University of Guilan, Rasht, 41335, Post Box: 1914, I. R. Iran
In this work, an efficient and green procedure have been described for the synthesis of
tetrahydrobenzimidazo[2,1-b]quinazolin-1(2Hꢀ-one derivatives using nanoporous sodium montmo-
rillonite clay (Na+-MMT) modified with 1-methyl-3-(trimethoxysilylpropyl)-imidazolium hydrogen sul-
fate (Na+-MMT-[pmim]HSO4ꢀ. The procedure gave the products in excellent yields in very short
reaction times under solvent-free condition. Also this catalyst can be reused for six times without
considerable loss of its catalytic activity.
Keywords: Sodium
Montmorillonite,
Na+-MMT-[pmim]HSO4,
2-Aminobenzimidazole,
Tetrahydrobenzimidazo[2,1-b]Quinazolin-1(2Hꢀ-Ones, Ionic Liquids.
IP: 188.72.96.58 On: Sun, 10 Jun 2018 12:24:55
Copyright: American Scientific Publishers
Delivered by Ingenta
1. INTRODUCTION
alcohols.23 In continuation of study about catalytic appli-
cations of Na+-M MT-[pmim]HSO4 and for overcome the
mentioned disadvantages for the synthesis of benzimidazo-
quinazolinones, we interested to used this reagent for the
synthesis of mentioned compounds.
Quinazolinone derivatives are interesting class of het-
erocyclic compounds that have a broad scope of bio-
logical and pharmacological activities.1–12 For example,
Quazinone, Anagrelide and Alfuzosin are some of com-
mercial drugs which have quinazolinone motif in their
structures (Fig. 1).13 Benzimidazo-quinazolinones are one
of important class of N -fused quinazolinones. The most
simple and straightforward protocol for the preparation
of benzimidazo-quinazolinones is based on the condensa-
tion of substituted aldehydes with 2-aminobenzimidazole
as amine sources and dimedone (5,5-dimethyl-1,3-
cyclohexanedione). For the promotion of this synthesis
a variety of catalysts have been reported.14–21 However,
harsh reaction conditions, long reaction times, use of toxic
reagents and need to organic solvents are some of disad-
vantages of the reported methods.
2. EXPERIMENTAL SECTION
2.1. Material
Chemicals were purchased from Fluka, Merck, Aldrich
Chemical Companies. Yields refer to isolated products.
Products were characterized by their physical constants,
comparison with authentic samples and FT-IR. The purity
determination of the substrate and reaction monitor-
ing were accomplished by TLC on silics-gel polygram
SILG/UV 254 plates.
2.2. Instrumentation
Very recently, we have reported the preparation and
characterization of a new Brönsted acidic ionic liquid sup-
ported on nanoporous sodium montmorillonite (Na+-M
MT-[pmim]HSO4ꢀ (Fig. 2), and its applicability in the syn-
thesis of the 4,4ꢀ-(arylmethylene)-bis-(3-methyl-1-phenyl-
1H-pyrazol-5-ols)22 and for the formylation of amines and
The FT-IR spectra were run on a VERTEX 70 Brucker
company (Germany). Thermogravimetric analyses (TGA)
were performed on TG/DTA6300 Sll-Nonotechnology
Comꢁpany (Japan). Samples were heated from 25 to
ꢁ
700 C at ramp 10 C/min under N2 atmosphere. Scan-
ning election microphotographs (SEM) were obtained on
aSEM-Philips XL30. Wide-angle X-ray diffraction (XRD)
∗Author to whom correspondence should be addressed.
1194
J. Nanosci. Nanotechnol. 2018, Vol. 18, No. 2
1533-4880/2018/18/1194/005
doi:10.1166/jnn.2018.13954

Shirini et al.
Facile and Efficient Synthesis of Tetrahydrobenzimidazo [2,1-b]Quinazolin-1(2H)-One Derivatives
H
Table I. Optimization of the reaction conditions catalyzed by Na+-
MMT-[pmim]HSO4.
H3CO
H3CO
N
N
N
O
N
O
Catalyst
(mg)
Temperature
(ꢁC)
Time
(min)
Conversion
(%)
NH2
Alfuzosin
Entry
Solvent
(α1receptor antagonist for benign prostatic hyperplasia)
1
2
3
4
5
6
7
8
9
10
50
50
50
50
50
50
50
40
20
60
H2O
C2H5OH
CH3CN
100
90
80
3.5 h
4 h
3 h
30
18
10
10
30
1.5 h
12
100
60
100
80
100
100
100
100
80
H
H
N
N
N
N
O
O
–
–
–
–
–
–
–
90
N
N
Cl
100
110
120
110
110
110
Cl
Cl
Anagrelide
(overproduction of blood platelets)
Quazinone
(a cardiotonic and vasodilator drug)
Figure 1. Some of drugs with quinazolinone motif.
100
measurements were performed at room temperature on a
Siemens D-500 X-ray diffractometer (Germany), using Ni-
filtered Co-Kꢁ radiation (ꢂ = 0ꢃ15418 nm).
3,3-dimethyl-12-(4-thiomethyl-phenyl)-3,4,5,12-tetra
hydrobenzimidazo [2,1-b]quinazolin-1(2H)-one: IR (neat)
ꢄ = 3418, 3148, 2954, 1671, 1568, 1375, 1262, 744 cm−1
;
1H NMR (DMSO-d6, 400 MHz): ꢅ = 1ꢃ05 (6H, s, CH3ꢀ,
2.15 (4H, s, CH3ꢀ, 2.40 (3H, s, SCH3ꢀ, 6.12 (1H, s),
6.93 (2H, d, J = 8ꢃ0 Hz), 7.03 (2H, d, J = 7ꢃ6 Hz),
7.07–7.11 (2H, m), 7.25–7.28 (2H, m), 7.65 (1H, s, NH)
ppm; 13C NMR (DMSO-d6, 100 Mz): ꢅ = 15ꢃ8, 28.8,
30.3, 31.6, 48.8, 111.8, 114.8, 122.1, 126.1, 128.1, 132.7,
133,1, 142.8, 152.5 ppm.
2.3. General Procedure for the
Synthesis of Tetrahydrobenz
Imidazo[2,1-b]Quinazolin-1(2H)-One Derivatives
A mixture of the requested aldehyde (1 mmol), 2-amino
benzimidazole (1 mmol), dimedone (1 mmol), Na+-MMT-
[pmim]HSO4 (50 mg, 5 mol%) was heated at 110 ꢁC under
solvent-free conditions. After completion of the reaction
(monitored by thin layer chromatography), ethanol was
added for the separation of catalyst by filtration. The pre-
cipitated product was purified by aqueous EtOH. The spec-
3,3-dimethyl-12-(4-cyano-phenyl)-3,4,5,12-tetrahydro
benzimidazo[2,1-b]quinazolin-1(2H)-one: IR (neat) ꢄ =
3425, 3045, 2962, 2227, 1567, 1448, 1358, 1264,
748 cm−1; 1H NMR (DMSO-d6, 400 MHz): ꢅ = 0ꢃ92 (3H,
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tral data of some of compounds are presented below:
Copyright: American Scientific Publishers
s, CH ꢀ, 1.07 (3H, s, CH ꢀ, 2.07 (1H, d, J = 16ꢃ0 Hz),
Delivered by Ingenta
3
3
2.28 (1H, d, J = 16ꢃ0 Hz), 2.67–2.69 (2H, m), 6.56
(1H, s), 6.98 (1H, td, J1 = 8ꢃ0 Hz, J2 = 0ꢃ8 Hz), 7.08 (1H,
td, J1 = 8ꢃ2 Hz, J2 = 0ꢃ8 Hz), 7.41 (1H, d, J = 8ꢃ0 Hz),
7.24 (1H, d, J = 8ꢃ0 Hz), 7.54 (2H, dd, J1 = 5ꢃ0 Hz,
J2 = 1ꢃ6 Hz), 7.75 (2H, dd, J1 = 5ꢃ0 Hz, J2 = 1ꢃ6 Hz),
11.26 (1H, s, NH) ppm.13 C NMR (DMSO-d6, 100 Mz):
Sampel solubility was too low for 13C NMR.
3,3-dimethyl-12-(2-naphthyl)-3,4,5,12-tetrahydrobenzo
[4,5]imidazo[2,1-b]quinazolin-1(2H)-one: IR (neat) ꢄ =
1
3443, 3050, 2964, 1575, 1370, 1261, 746 cm−1; H NMR
(DMSO-d6, 400 MHz): ꢅ = 0ꢃ94 (3H, s, CH3ꢀ, 1.08
(3H, s, CH3ꢀ, 2.04 (1H, d, J = 16ꢃ0 Hz), 2.29 (1H,
d, J = 16ꢃ0 Hz), 2.67–274 (2H, m), 6.60 (1H, s), 6.93
(1H, t, J = 7ꢃ6 Hz), 7.03 (1H, t, J = 7ꢃ6 Hz), 7.31
(2H, m), 7.38 (1H, d, J = 8ꢃ0 Hz), 7.49 (2H, m), 7.80
(2H, t, J = 7ꢃ6 Hz), 7.92 (1H, d, J = 7ꢃ6), 8.04 (1H, s),
Figure 2. The acidic ionic liquid immobilized on Na+-MMT (Na+-
MMT-[pmim]HSO4ꢀ.
Scheme 1. Synthesis
of
tetrahydrobenzimidazo[2,1-b]quinazolin-
1(2Hꢀ-one derivatives catalyzed by Na+-MMT-[pmim]HSO4.
J. Nanosci. Nanotechnol. 18, 1194–1198, 2018
1195

Facile and Efficient Synthesis of Tetrahydrobenzimidazo [2,1-b]Quinazolin-1(2H)-One Derivatives
Table II. Preparation of tetrahydrobenzimidazo[2,1-b]quinazolin-
Shirini et al.
1H NMR (DMSO-d6, 400 MHz): ꢅ = 0ꢃ96 (3H, s, CH3ꢀ,
1.08 (3H, s, CH3ꢀ, 2.07 (1H, d, J = 16ꢃ0 Hz), 2.28 (1H,
d, J = 16ꢃ0 Hz), 2.65–2.69 (2H, m), 3.85 (2H, s, CH2ꢀ,
6.50 (1H, s), 6.96 (1H, td, J1 = 7ꢃ2 Hz, J2 = 1ꢃ2 Hz),
7.05 (1H, td, J1 = 7ꢃ2 Hz, J2 = 1ꢃ2 Hz), 7.28 (1H, td,
J1 = 7ꢃ2 Hz, J2 = 1ꢃ2 Hz), 7.31 (2H, d, J = 7ꢃ6 Hz),
7.38 (2H, d, J = 7ꢃ6 Hz), 7.54 (1H, d, J = 7ꢃ2 Hz),
7.54 (1H, s), 7.78 (1H, d, J = 7ꢃ6 Hz), 7.81 (1H, d,
J = 7ꢃ2 Hz), 11.1 (1H, s, NH) ppm; 13C NMR (DMSO-d6,
100 Mz): Sampel solubility was too low for 13C NMR.
1(2Hꢀ-one derivatives catalyzed by Na+-MMT-[pmim]HSO4.
Melting point (ꢁC)
Time Yield
(min) (%) Found
Reported
[Refs.]
Entry
Ar
X
1
2
3
4
5
6
7
8
C6H5–
2-ClC6H4–
3-ClC6H4–
4-ClC6H4–
3-BrC6H4–
4-BrC6H4–
2-CH3C6H5–
4-CH3C6H5–
3-CH3OC6H5–
4-CH3OC6H5–
NH 16
NH 28
NH 14
NH 14
NH 20
NH 14
NH 45
NH 14
NH 20
NH 30
NH 60
NH 18
NH 10
NH 15
NH 15
92
>350
>30016
89 340–342 >30014
90 340–342 >30014
87
89 334–336 >30014
90 >350
>30016
>350
>30016
88 334–336 >30014
92 340–342 330–33215
92 320–322 325–32715
90 340–342 >30016
91 332–334 >30016
93 335–337 >30014
94 344–346 >30016
92 342–344 342–34424
94 340–342 340–34224
3. RESULTS AND DISCUSSION
9
For optimization of the reaction conditions, the con-
densation of 4-nitrobenzaldehyde, 2-aminobenzimidazole
and dimedone leading to 3,3-dimethyl-12(4-nitro-phenyl)-
3,4,5,12-tetrahydrobenzo[4,5]imidazo[2,1-b]quinazolin-1(2Hꢀ-
one was selected as a model reaction in various conditions
(Table I). For choosing the reaction media, different sol-
vents (EtOH, H2O, CH3CN) and solvent-free conditions
were employed which the best results were obtained in
the solvent-free condition. Further experiments showed
that 50 mg of Na+-MMT-[pmim]HSO4 was the optimal
catalyst loading for this reaction, and higher catalyst
loading did not improve the yield of the product to a
greater extent. In addition, the experiments showed that
the reaction at 110 ꢁC proceeded in highest yield and
10
11
12
13
14
15
4-OHC6H4
–
3-NO2C6H4–
4-NO2C6H4–
4-CH3SC6H5–
4-CNC6H5–
16
NH 20
93 344–346 344–34524
17
18
19
20
NH 30
92 347–349 347–34924
93 224-226 227–22914
C6H5–
2-CH3OC6H5–
3-CH3OC6H5–
S
S
S
90
120 91 235–237 236–24014
60
92 240–242 243–24514
shortest time. Finally the best result was obtained using
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50 mg of Na + -MMT-[pmim]HSO at 110 ꢁC under
Copyright: American Scientific Publishers
4
13
Delivered by Ingenta
11.19 (1H, s, NH) ppm; C NMR (DMSO-d6, 100 Mz):
solvent-free conditions (Scheme 1).
Sampel solubility was too low for 13C NMR;
After the optimization of the reaction conditions, the
protocol were explored with a variety of simple read-
ily available substrates under the optimal conditions
(Table II). It was observed that under similar conditions,
12-(2-fluorenyl)-3,3-dimethyl-3,4,5,12-tetrahydrobenzo
[4,5]imidazo[2,1-b]quinazolin-1(2H)-one: IR (neat) ꢄ =
3431, 3047, 3229, 2908, 1575, 1372, 1264, 741 cm−1
;
Table 2, entry 4
Table 2, entry 14
Table 2, entry 15
Table 2, entry 16
Figure 3. The changes of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2Hꢀ-one derivatives from visible to fluorescence wavelength.
J. Nanosci. Nanotechnol. 18, 1194–1198, 2018
Table 2, entry 17
1196

Shirini et al.
Facile and Efficient Synthesis of Tetrahydrobenzimidazo [2,1-b]Quinazolin-1(2H)-One Derivatives
Na+-MMT-[pmim]HSO4
Na+-MMT-[pmim]HSO4
Ar
O
O
O+δ
+δO
O
N
H
Ar
NH2
N
H
Ar
O
Ar
O
Ar
N
O
H
N
N
N
N
O+δ
N
N
H
NH2
N
OH
H
Product
Na+-MMT-[pmim]HSO4
Scheme 2. Proposed mechanism for the synthesis of tetrahydrobenzimidazo [2,1-b]quinazolin-1(2Hꢀ-one derivatives catalyzed by Na+-MMT-
[pmim]HSO4.
times (Table II, entries 1–15). As can be seen, the steric
effects show a very small influence on the reaction times
(Table II, entries 2 and 7). In addition, polycyclic aro-
matic aldehyde containing 2-naphthaldehyde and fluorene-
2-carbaldehyde also provided the desired products in very
good yields (Table II, entries 16–17).
In continue, we performed reactions using 2-amino-
benzothiazole instead of 2-aminobenzimidazole. As it is
clear, these reactions were also carried out with high yield
but in longer reaction time than 2-aminobenzimidazole
IP: 188.72.96.58 On: Sun, 10 Jun 2018 12:24:55
(Table II, entries 18–20).
Copyright: American Scientific Publishers
It is found that these products showed strong fluores-
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cence emission. The changes of some of these derivatives
from visible to fluorescence wavelength (at 365 nm) were
displayed in Figure 3.
Figure 4. Reusability of the catalyst.
The proposed mechanism for the synthesis of
tetrahydrobenzimidazo[2,1-b]quinazolin-1(2Hꢀ-ones
in
a wide range of aromatic aldehydes containing electron-
withdrawing as well as electron-donating groups such as
Cl, Br, CH3, OCH3, OH, NO2, SCH3 and CN in various
positions of the benzene ring were successfully con-
verted to the corresponding tetrahydrobenzimidazo[2,1-
b]quinazolin-1(2Hꢀ-ones with high yields in short reaction
the presence of Na+-MMT-[pmim]HSO4 as a promoter
is shown in Scheme 2. On the basis of this mechanism,
Na+-MMT-[pmim]HSO4 catalyzes the reaction by the
activation of the carbonyl groups against the nucleophilic
attack.
Table III. Comparison of the result obtained from the synthesis of (I): 3,3-dimethyl-12-(4-nitro-phenyl)-3,4,5,12-tetrahydrobenzimidazo[2,1-b]
quinazolin-1(2Hꢀ-one (Table II, entry 13) and (II): 3,3-dimethyl-12-(4-methyl-phenyl)-3,4,5,12-tetrahydrobenzimidazo[2,1-b]quinazolin-1(2Hꢀ-one
(Table II, entry 8).
(I)
(II)
Entry
Catalyst (mol%)
Time (min)
Yield (%)
Time (min)
Yield (%)
Refs.
1
2
3
4
5
6
7
8
9
10
–
–
110 ꢁC/Solvent-free
Reflux/DMF
–
–
–
–
7 h
12 h
–
–
–
–
–
–
–
72
72
–
–
–
–
–
–
–
[14]
[15]
[16]
[17]
[19]
[20]
[21]
This work
This work
This work
H6P2W18O62 ·18H2O (1 mol%)
NH2SO3H (50 mol%)
I2 (10 mol%)
Reflux/CH3 CN
Reflux/CH3 CN
Reflux/CH3 CN
MW/120 ꢁC
10
18
10
5
20
60
30
10
99
95
69
95
98
90
91
94
SiO2
p-TSA (15 mol%)
50 ꢁC/CH3CN
Na+-MMT
110 ꢁC/Solvent-free
110 ꢁC/Solvent-free
110 ꢁC/Solvent-free
Na+-MMT-[pmim]Cl
Na+-MMT-[pmim]HSO4
14
92
J. Nanosci. Nanotechnol. 18, 1194–1198, 2018
1197

Facile and Efficient Synthesis of Tetrahydrobenzimidazo [2,1-b]Quinazolin-1(2H)-One Derivatives
Shirini et al.
To check the reusability of the catalyst, the reaction
of 4-nitrobenzaldehyde, 2-aminobenzimidazole and dime-
done under the optimized reaction conditions was studied
again. When the reaction completed, ethanol was added
and the catalyst was separated by filtration. The recovered
catalyst was washed with ethanol, dried and reused for the
same reaction. This process was carried out over six runs
and all reactions led to the desired products without sig-
nificant changes in terms of the reaction time and yield
which clearly demonstrates practical recyclability of this
catalyst (Fig. 4).
Acknowledgments: The authors are grateful to the
Guilan University Research Council for the partial support
of this work.
References and Notes
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To highlight the merits of our newly developed pro-
cedures, we have compared our results obtained for
the synthesis of and 3,3-dimethyl-12-(4-nitro-phenyl)-
3,4,5,12-tetrahydrobenzimidazo[2,1-b]quinazolin-1(2Hꢀ-one
(Table III, entry 13) and 3,3-dimethyl-12-(4-methyl-phenyl)-
3,4,5,12-tetrahydrobenzimidazo[2,1-b]quinazolin-1(2Hꢀ-one
(Table III, entry 8) using the Na+-MMT-[pmim]HSO4
catalyst with other results reported in the literature for the
same transformation. As shown in Table III, the newly
developed method avoids some of the disadvantages asso-
ciated with the other procedures such as long reaction
time, large excesses of reagents, use of organic solvents,
reflux conditions, toxic reagents and low yields of the
products. This comparison also clarifies an important
point about the catalyst. As it can be seen, Na+-MMT
and Na+-MMT-[pmim]Cl are also able to catalyze this
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IP: 188.72.96.58 On: Sun, 10 Jun 2018 12:24:55
type of reactions, but in longer reaction times rather
Copyright: American Scientific Publishers
than Na+-MMT-[pmim]HSO . These results give clear
Delivered by Ingenta
4
evidence to confirm the important role of the covalently
bounded ionic liquid and also HSO−4 group in the catalyst
to obtain the best performance.
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Intermediates 42, 1759 (2016).
4. CONCLUSIONS
In conclusion, in this study we have introduced Na+-
MMT-[pmim]HSO4 as a highly powerful supported
acidic ionic liquid for the simple and efficient synthe-
sis of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2Hꢀ-one
derivatives. The obtained results show that this method
is convincingly superior to other reported procedures in
terms of the reaction times and yields. Simple experimen-
tal procedure and use of reusable catalyst with lower load-
ing are other advantages of this procedure. Furthermore,
this process avoids problems associated with organic sol-
vents and liquid acids use, which makes it a useful and
attractive strategy in view of economic and environmental
advantages.
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Received: 27 August 2016. Accepted: 15 October 2016.
1198
J. Nanosci. Nanotechnol. 18, 1194–1198, 2018