Nano-indium oxide: An efficient catalyst for one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-ones with a greener prospect

Article abstract of DOI:10.1016/j.catcom.2014.01.032

Nano-In₂O₃ is found to be a remarkable efficient catalyst for the one-pot three-component condensation of isatoic anhydride, primary amine or ammonium salts and aromatic aldehydes for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones in aqueous media. In₂O₃ nanoparticles are easily recyclable without the significant loss of catalytic activities.

Full text of DOI:10.1016/j.catcom.2014.01.032

Catalysis Communications 49 (2014) 52–57
Contents lists available at ScienceDirect
Catalysis Communications
journal homepage: www.elsevier.com/locate/catcom
Short Communication
Nano-indium oxide: An efficient catalyst for one-pot synthesis
of 2,3-dihydroquinazolin-4(1H)-ones with a greener prospect
⁎
Sougata Santra, Matiur Rahman, Anupam Roy, Adinath Majee, Alakananda Hajra
Department of Chemistry, Visva-Bharati (A Central University), Santiniketan 731235, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Nano-In2O3 is found to be a remarkable efficient catalyst for the one-pot three-component condensation
of isatoic anhydride, primary amine or ammonium salts and aromatic aldehydes for the synthesis of
2,3-dihydroquinazolin-4(1H)-ones in aqueous media. In2O3 nanoparticles are easily recyclable without the
significant loss of catalytic activities.
Received 1 December 2013
Received in revised form 29 January 2014
Accepted 30 January 2014
Available online 7 February 2014
© 2014 Elsevier B.V. All rights reserved.
Keywords:
Nano-In2O3
Multicomponent reaction
Quinazolinones
Aqueous media
Gram-scale synthesis
1. Introduction
often experimentally simple fashion [13–15]. For this reason, MCRs are
particularly well suited for diversity oriented synthesis and library syn-
The last decade has witnessed tremendous growth in the field of
nanoscience and nanotechnology. The easy accessibility to nanoparti-
cles has prompted investigations on their applications in catalysis. Sev-
eral reports showed an amazing level of their performance as catalysts
in terms of selectivity, reactivity, and improved yields of products
[1,2]. In addition, the high surface-to-volume ratio of nanoparticles pro-
vides a larger number of active sites per unit area compared to their het-
erogeneous counterparts. Thus, in recent times, interest in nanoparticle
catalysis has increased considerably because of their high efficiency
under environmentally benign reaction conditions [3]. As a part of the
continuous interest in indium catalysis [4,5], we have demonstrated
the catalytic activity of indium in various multicomponent reactions
(MCRs) leading to molecules of biological and pharmaceutical impor-
tance. Indium(III) compounds are mild and water-tolerant Lewis acids
and show high regio-, stereo-, and chemoselectivity [6–8]. However,
until now, the use of nano-In2O3 as a catalyst is limited in organic syn-
thesis [9–12]. Recently, we found that nano-In2O3 is a very effective
and reusable catalyst for useful chemical transformations [10–12].
This inspired us to focus on the use of nano-In2O3 as a catalyst in
multicomponent reactions.
thesis of drug like compounds, which are an essential part of the re-
search performed in agrochemical and pharmaceutical companies
[16]. Indeed, the concept of environmental factor (E-factor) and atom
economy has been gradually included into conventional organic synthe-
sis in both industry and academia. The use of solvent is the main reason
for an insufficient E-factor, especially in synthesis of fine chemicals and
pharmaceutical industries [17].
Quinazolinone derivatives are a class of fused nitrogen containing
heterocycles that have drawn much attention due to their potential
biological and pharmaceutical activities including antifertility, anti-
bacterial, antitumor and monoamine oxidase inhibitory activity
[18,19]. In addition, these compounds can easily oxidize to their
quinazolin-4(3H)-one analogs, which are themselves important bio-
logically active heterocyclic compounds and can also be found in
some natural products [20]. Quinazolinone scaffolds are also impor-
tant for the establishment of some commercially available drugs
(Fig. 1) [21].
Due to their immense biological activities, synthesis of quinazolinone
derivatives is a demanding task. Numerous protocols have been devel-
oped for the synthesis of quinazolinone derivatives using silica sulfuric
acid [22], zinc(II) perfluorooctanoate [Zn(PFO)2] [23], gallium(III)
triflate [24], KAl(SO4)2·12H2O [25], MCM-41-SO3H [26], nano-Fe3O4
[27], 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4)
[28], molecular I2 [29], β-cyclodextrin [30], etc. Regardless of their
efficiency and reliability, most of these methods suffer from one or
more of these disadvantages, such as the use of hazardous organic
solvents, low yields, strongly acidic conditions, expensive moisture-
sensitive catalysts, and tedious work-up procedure.
Recently, multicomponent reactions (MCRs) are one of the most
powerful and efficient tools in organic synthesis for the synthesis of bi-
ologically important compounds in the perspective of green chemistry.
In addition, MCRs offer molecular diversity and complexity in a fast and
⁎
Corresponding author. Tel./fax: +91 3463 261526.
E-mail address: alakananda.hajra@visva-bharati.ac.in (A. Hajra).
1566-7367/$ – see front matter © 2014 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.catcom.2014.01.032

S. Santra et al. / Catalysis Communications 49 (2014) 52–57
53
CH3
Table 1
O
Optimization of the reaction conditions.a
N
O
N
O
CH3
N
H
N
NH
CH3
CH3
N
H
O
Entry
Catalyst (mol%)
Solvents
Time (h)
Yieldb (%)
Methaqualone
Benzouracil
Metabotropic glutamate receptor
1
2
3
Nano-In2O3 (5)
Nano-In2O3 (5)
Nano-In2O3 (5)
Nano-In2O3 (5)
Nano-In2O3 (5)
Nano-In2O3 (5)
Nano-In2O3 (5)
Nano-In2O3 (5)
Nano-In2O3 (5)
Nano-In2O3 (2)
Nano-In2O3 (10)
Nano-In2O3 (5)
Nano-In2O3 (5)
Nano-In2O3 (5)
Nano-In2O3 (5)
Nano-In2O3 (5)
In2O3 powder (5)
Nano-NiO 5)
EtOH
H2O
MeOH
4
4
6
4
4
4
6
6
6
6
4
6
6
6
6
6
6
6
6
6
6
72
75
68
80
87
77
74
76
74
76
87
44
48
36
40
46
62
55
58
65
b25
Fig. 1. Some important drugs with quinazolinone skeleton.
4
H2O/EtOH (1:1)
H2O/EtOH (2:1)
H2O/EtOH (1:2)
H2O/MeOH (1:1)
H2O/MeOH (2:1)
H2O/MeOH (1:2)
H2O/EtOH (2:1)
H2O/EtOH (2:1)
DMF
MeCN
Toluene
1,4-Dioxane
1,2-DCE
5c
6
7
8
9
Very recently, we have developed an environmentally benign nano-
CuO catalyzed “on-water” strategy for the one-pot synthesis of
isoindolo[2,1-a]quinazolines by a three-component coupling of isatoic
anhydride, 2-carboxybenzaldehyde and amines (Scheme 1a) [31]. So,
in continuation of our efforts in the field of nanocatalysis [10–12,31]
herein, we report a remarkable catalytic activity of nano-In2O3 in one-
pot protocol for the synthesis of 2,3-dihydroquinazolin-4(1H)-one de-
rivatives by a three-component condensation of isatoic anhydride
with primary amines or ammonium salts and aromatic aldehydes in
aqueous medium (Scheme 1b).
10
11
12
13
14
15
16
17
18
19
20
21
H2O/EtOH (2:1)
H2O/EtOH (2:1)
H2O/EtOH (2:1)
H2O/EtOH (2:1)
H2O/EtOH (2:1)
Nano-ZnO (5)
Nano-CuO (5)
–
a
2. Experimental section
Reaction conditions: 1 mmol of 1 and 1.1 mmol of 2a and 1 mmol of 3a in
the presence of catalyst in solvent (3 mL) at 80 °C.
b
Isolated yields.
Optimized reaction conditions.
2.1. General procedure for the synthesis of 2,3-dihydro-2-phenylquinazolin-
4(1H)-one
c
To a mixture of isatoic anhydride (1 mmol), primary amine
(1.1 mmole) or ammonium salt (ammonium carbonate, 0.6 mmol,
ammonium acetate, 1.2 mmol, or ammonium chloride, 1.2 mmole)
and aldehyde (1 mmol) were stirred in the presence of commercially
available In2O3 nanopowder (5 mol%, 0.013 g) in water/ethanol
(2:1, 3 mL) under 80 °C for 4 h. After completion of the reaction,
the reaction mixture was cooled to room temperature and nano-In2O3
was recovered by centrifugation. Then the ethanol was evaporated in
rotary evaporator and the solid separated was filtered under suction.
The solid crude was washed with cold water and recrystallized from
EtOH to afford the analytically pure product.
2.2. Procedure for recycling the catalyst
After completion, the nano-In2O3 was separated from the reaction
mixture by ultra centrifugation, washed with water, dried under vacuum
followed by at 110 °C for 2 h and reused for further catalytic reactions.
(a) Our previous work:
O
O
NH2
Nano CuO (5 mol%)
N
CHO
O
+
+
Water, 10h, Reflux
N
COOH
O
N
H
O
(b) This work:
O
O
CHO
NH2
Nano In2O3(5 mol%)
N
O
+
+
Water/EtOH
4h, 80 oC
N
H
O
N
H
O
O
CHO
Nano In2O3(5 mol%)
NH
O
+
NH4+X-
+
Water/EtOH
4h, 80oC
N
H
O
N
H
X=OAc-, Cl-, CO3
-
Scheme 1. Synthesis of quinazolinone derivatives.

54
S. Santra et al. / Catalysis Communications 49 (2014) 52–57
Table 2
Substrates scope.a
Entry
R
R1
Product
Yieldb (%)
Mp (°C)
Found
Reported [ref]
1
2
3
4
5
6
7
8
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
87, 82c
88
83
81
79
81
83
87
80
78
81
80
80
85
87
203–204
213–214
204–205
221–222
193–194
218–220
213–214
195–196
214–215
183–184
223–224
212–214
214–215
246–248
238–240
203–205 [23]
214 [27]
204–205 [23]
222–225 [23]
195–196 [23]
4-MeC6H4
4-MeOC6H4
4-BrC6H4
4-NO2C6H4
2-BrC6H4
4-ClC6H4
Ph
Ph
Ph
Ph
Ph
214–217 [29]
196–198 [23]
216–218 [29]
185–187 [23]
224–226 [23]
215–216 [27]
215–216 [29]
247–249 [27]
4-MeC6H4
4-ClC6H4
4-NO2C6H4
4-BrC6H4
2-ClC6H4
4-MeOC6H4
4-MeC6H4
4-MeC6H4
9
10
11
12
13
14
15
Ph
4-MeOC6H4
Piperonyl
a
Reaction conditions: 1 mmol of 1 and 1.1 mmol of 2 and 1 mmol of 3 in the presence of nano-In2O3 (5 mol%) in water/ethanol (2:1, 3 mL) at 80 °C for 4 h.
Isolated yield.
Isatoic anhydride (1, 20 mmol), aniline (2a, 22 mmol) and benzaldehyde (3a, 20 mmol) in the presence of nano In2O3 (5 mol%) in water/ethanol (2:1, 60 mL) at 80 °C for 4 h.
b
c
3. Results and discussion
(2a, 1 mmol) and aniline (3a, 1.1 mmol) in the presence of
5 mol% of nano-In2O3 in a mixture of water and EtOH (2:1) at 80 °C
(entry 6, Table 1) for 4 h.
We commenced our study taking isatoic anhydride (1), benzalde-
hyde (2a) and aniline (3a) as the model substrates in the presence of
catalytic amount of nano-In2O3 (5 mol%) in EtOH at 80 °C for 4 h
(Table 1, entry 1). To our delight, desired quinazolinone derivative
was obtained in 72% yield after 4 h and no further improvement
was noticed by increasing reaction time. Encouraged by this initial
result, we proceeded to optimize the reaction conditions which are
summarized in Table 1. Water/ethanol (2:1) mixture appeared to
be the best choice among the common solvents such as MeOH,
CH3CN, toluene, dioxane, and 1,2-DCE. Lower conversions were ob-
tained when indium oxide powder. Nano-In2O3 was found to be
the most effective catalyst among the various metal nanocatalysts
tested (In2O3, NiO, ZnO, CuO) and 5 mol% nano-In2O3 proved to be
optimal. With respect to the quantity of the catalyst, there was no
significant enhancement in yields when the amount of catalyst was
increased from 5 to 10 mol% while decreasing the amount of catalyst
decreased the yield. In the absence of catalyst, negligible amount of
desired product was observed. Thus, optimal reaction conditions
were obtained using isatoic anhydride (1, 1 mmol), benzaldehyde
After optimization, we explored the scope of this reaction by using
various substituted aromatic aldehydes and amines to prove the general
applicability of the reaction conditions (Table 2). The bromo- and
chloro-substituted benzaldehydes afforded the corresponding products
4f and 4g in 81% and 83% yields respectively. We were pleased to notice
that under the stated conditions, anilines substituted with halogens
such as \Cl and \Br (4i, 4k and 4l) smoothly reacted with benzalde-
hyde without forming any dehalogenated products. Aldehyde as well
as amine containing electron donating \OMe group on the aromatic
ring have shown also good efficiency (4c and 4m). We are delighted
to find that the acid sensitive aldehyde such as piperonal is well tolerat-
ed under our catalytic conditions with 87% isolated yield (4o). It is well
known that ammonium salts (carbonate, chloride, and acetate) are the
source of ammonia in the synthesis of nitrogen-containing heterocyclic
compounds. Accordingly, corresponding 2,3-dihydroquinazoloin-4-
(1H)-ones (6a–6f) were synthesized efficiently using ammonium car-
bonate or ammonium chloride or ammonium acetate (5), isatoic anhy-
dride 1 and aldehyde 5 (Table 3). This methodology is also applicable
Table 3
Synthesis of 2,3-dihydroquinazolin-4(1H)-ones using ammonium salts.a
Entry
Ammonium salts (5)
R1
Product
Yieldb (%)
Mp (°C)
Found
Reported [ref]
1
2
3
4
5
6
NH4OAc
NH4OAc
NH4OAc
NH4Cl
NH4Cl
(NH4)2CO3
Ph
6a
6b
6c
6d
6e
6f
89
88
83
87
88
86
223–224
228–230
206–207
225–227
231–233
223–225
225–226 [29]
229–231 [29]
207–208 [29]
225–226 [29]
229–231 [29]
225–226 [29]
4-MeC6H4
4-ClC6H4
Ph
4-MeC6H4
Ph
a
Isatoic anhydride (1 mmol), ammonium salts (ammonium carbonate, 0.6 mmol, ammonium acetate, 1.2 mmol, or ammonium chloride, 1.2 mmol) and aldehyde (1 mmol) in the
presence of nano-In2O3 (5 mol%) in water/ethanol (2:1, 3 mL) under 80 °C for 4 h.
b
Isolated yield.

S. Santra et al. / Catalysis Communications 49 (2014) 52–57
55
Table 4
fresh catalyst and the recovered catalyst after six cycles (Figs. 2 and 3)
shows that the catalyst does not undergo agglomeration during the
recycling process.
Recycling of In2O3 nanoparticle for synthesizing 4a.a
No. of cycle
Yieldb (%)
Catalyst recovery (%)
Based on the literature reports [23,24] a plausible mechanism for
the formation of 2,3-dihydroquinazolin-4(1H)-ones is exposed in
Scheme 2. At first the isatoic anhydride is activated by nano-In2O3
followed by the N-nucleophilic amine attacks on the carbonyl to
form T.S.-I. T.S.-I gets more stability which in turn leads to the forma-
tion of intermediate A by elimination of CO2. After that intermediate
A reacts with the aldehydes in the presence of nano-In2O3 to form
the intermediate B which upon intramolecular cyclization afforded
the final product 4. Nano-In2O3 might activate the aldehyde through
coordination with the oxygen of the corresponding carbonyl group
which facilitates the subsequent nucleophilic attack by the nitrogen
atom on the carbonyl carbon. Nano-In2O3 is the most efficient among
the nanometal oxides for this transformation (Table 1) probably due
to its low and selective heterophilicity [6–8,33].
1
2
3
4
5
6
87
85
82
82
79
76
98
96
94
91
90
88
a
Carried out with 1 mmol of 1 and 1.1 mmol of 2a and 1 mmol of 3a in the presence of
catalyst in water/ethanol (2:1, 3 mL) at 80 °C for 4 h.
b
Isolated yields.
on a gm-scale synthesis also. We have successfully prepared the
quinazolinone 4a in 82% yield by the reaction of isatoic anhydride
(1, 20 mmol), aniline (2a, 22 mmol) and benzaldehyde (3a, 20 mmol).
In addition, we have developed a greener reaction condition bearing
lower E-factor [17,32]of 0.42 and 0.39 in cases of synthesizing 4a and 4b
respectively (see Supplementary data).
4. Conclusions
To check the recyclability of the catalyst, it was separated from the
reaction mixture by ultra centrifugation, washed with water, dried
under vacuum followed by drying at 110 °C and reused for further reac-
tions. The catalyst maintained its high level of activity even after being
recycled six times for synthesizing 4a as shown in Table 4.
In conclusion, we have developed an efficient nano-In2O3 catalyzed
one-pot three-component condensation reaction of isatoic anhydride,
aldehydes, and amines or ammonium salts under environmental-
ly benign reaction conditions. A library of quinazolinone de-
rivatives was prepared from easily available starting materials.
The catalyst was recovered and reused for six times without
The morphology of nano-In2O3 was determined by HRTEM and pow-
der XRD. A comparative study of the HRTEM and powder XRD of the
Fig. 2. HRTEM images of (a) fresh In2O3 nanoparticles and (b) In2O3 nanoparticles after the sixth cycle.
a
b
3000
+(222)
3000
2500
2000
1500
1000
500
+(222)
2500
2000
1500
+(440)
+(440)
1000
500
0
+(400)
+(400)
+(622)
+(622)
+(211)
+(211)
+(431)
+(411)
+(431)
+(411)
0
20
40
60
80
100
20
40
60
80
100
2θ (degree)
2θ (degree)
Fig. 3. Powder X-ray diffraction patterns of (a) fresh In2O3 nanoparticles and (b) In2O3 nanoparticles after the sixth cycle.

56
S. Santra et al. / Catalysis Communications 49 (2014) 52–57
O
R
NH2
O
O
2
N
H
O
O
1
N
H
O
O
H
N
R
H
O
O
In2O3 nano
HN
NHR
NH2
O
A
TS-I
(Isolable)
O
N
O
CO2
R
N
H
R1
H
R1
H
O
B
R1
H
3
H
N
O
O
O
R
R
+H+
R
-H+
N
N
R1
R1
R1
N
N
H
N
C
4
D
Scheme 2. Plausible mechanism.
significant loss of catalytic activities. This protocol is also applica-
ble on gram-scale synthesis. The significant advantages offered by
this method are: (i) use of greener solvent, (ii) good yields, (iii)
benign byproducts, (iv) low catalyst loading, (v) simple opera-
tion, and (v) lower E-factor. We believe that our new protocol
using nano-In2O3 will find widespread applications in academic
laboratories and industry and the above features makes this pro-
cedure truly environmentally benign.
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