Efficient one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-ones from aromatic aldehydes and their one-pot oxidation to quinazolin-4(3H)-ones catalyzed by Bi(NO3)3·5H2O: Investigating the role of the catalyst

Article abstract of DOI:10.1016/j.crci.2011.05.003

An efficient and novel synthesis of 2,3-disubstituted 2,3- dihydroquinazolin-4(1H)-ones via one-pot, three-component reaction of isatoic anhydride, primary amines and aromatic aldehydes catalyzed by Bi(NO ₃)₃·5H₂O under so

Full text of DOI:10.1016/j.crci.2011.05.003

C. R. Chimie 14 (2011) 944–952
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´
Full paper/Memoire
Efficient one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-ones from
aromatic aldehydes and their one-pot oxidation to quinazolin-4(3H)-
ones catalyzed by Bi(NO3)3Á5H2O: Investigating the role of the
catalyst
*
*
Iraj Mohammadpoor-Baltork , Ahmad R. Khosropour , Majid Moghadam,
Shahram Tangestaninejad, Valiollah Mirkhani, Saeid Baghersad, Arsalan Mirjafari
Department of Chemistry, Catalysis Division, University of Isfahan, Isfahan 81746-73441, Iran
A B S T R A C T
A R T I C L E I N F O
An efficient and novel synthesis of 2,3-disubstituted 2,3-dihydroquinazolin-4(1H)-ones
via one-pot, three-component reaction of isatoic anhydride, primary amines and aromatic
aldehydes catalyzed by Bi(NO3)3Á5H2O under solvent-free conditions is described.
Oxidation of these 2,3-dihydroquinazolin-4(1H)-ones to their quinazolin-4(3H)-ones
was also successfully performed in the presence of Bi(NO3)3Á5H2O. This new method has
the advantages of convenient manipulation, short reaction times, excellent yields, very
easy work-up, and the use of commercially available, low cost and relatively non-toxic
catalyst. The role of Bi(NO3)3Á5H2O was also investigated in these transformations.
ß 2011 Acade´mie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Article history:
Received 13 December 2010
Accepted after revision 10 May 2011
Available online 24 June 2011
Keywords:
Bismuth(III) nitrate pentahydrate
2,3-Dihydroquinazolin-4(1H)-ones
Quinazolin-4(3H)-ones
Solvent-free
1. Introduction
methods for their synthesis have been developed
with varying degree of success but with some limitations
The development of efficient and selective synthetic
transformations in one operation using readily available,
inexpensive and environmentally-benign catalysts and
reagents is of great interest in modern organic synthesis
[1]. Therefore, in recent years, synthetic chemists have
directed their researches toward the green synthesis. 2,3-
Dihydroquinazolin-4(1H)-ones are important heterocyclic
compounds that exhibit a broad range of pharmaceutical
activities including antifertility, antibacterial, antitumor,
antifungal, and also as a mono amine oxidase inhibitor [2–
4]. Moreover, 2,3-dihydroquinazolin-4(1H)-one deriva-
tives are the key intermediate for the synthesis of
quinazolin-4(1H)-one compounds. Due to the significant
interest in these heterocyclic compounds, a number of
[5–13].
2,3-Disubstituted quinazolin-4(3H)-ones are also im-
portant building blocks in the synthesis of many natural
products which display variety of biological and
a
pharmaceutical activities [14–16]. Known examples of
2,3-dihydroquinazoline-4(1H)-one drugs are diproqualone
I which is used for the treatment of inflammatory pain
associated with osteoarthritis, and methaqualone II which
has antimalarial effect and currently being used for the
assessment of the abuse liability of sedative hypnotic
drugs [16] (Scheme 1). Furthermore, quinazoline alkaloids
are an important class of natural products which possess
biological effects. Among them, pyrrolo[2,1-b]quinazoline
alkaloids such as isaindigotone III, deoxyvasicinone IV and
8-hydroxydeoxyvasicinone V exhibit anti-inflammatory,
antimicrobial and antidepressant activities. The related
alkaloid mackinazolinone VI possesses a broad spectrum of
pharmacological activities [17] (Scheme 1). In accordance
with the significance of quinazolin-4(3H)-ones, several
* Corresponding authors.
E-mail addresses: imbaltork@sci.ui.ac.ir (I. Mohammadpoor-Baltork),
khosropour@chem.ui.ac.ir (A.R. Khosropour).
1631-0748/$ – see front matter ß 2011 Acade´mie des sciences. Published by Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.crci.2011.05.003

I. Mohammadpoor-Baltork et al. / C. R. Chimie 14 (2011) 944–952
945
Scheme 1. Structure of some quinazoline-based drugs.
synthetic methods have been developed for the construc-
were obtained on
a
platform II spectrometer from
tion of this kind of fused heterocycles from suitable
precursors [18–29].
Micromass; EI mode at 70 eV. Elemental analysis was
performed on LECO, CHNS-932. All products were charac-
terized by their physical and spectral data.
In recent years, Bi(III) salts have attracted the attention
of synthetic organic chemists as effective catalysts because
of their low toxicity, ease of handling, low cost and relative
insensitivity to air and moisture [30–32]. As a part of our
continuing research on the development of environmen-
tally friendly synthetic methods of important organic
compounds [33–39] and also on the application of Bi(III)
salts in organic synthesis [31,40–45], we would like to
report a new, efficient and highly selective one-pot
synthesis of 2,3-disubstituted 2,3-dihydroquinazolin-
4(1H)-ones and their one-pot oxidation to quinazolin-
4(3H)-ones using Bi(NO3)3Á5H2O under solvent-free con-
ditions (Scheme 2).
2.2. General procedure for the synthesis of 2,3-disubstituted
2,3-dihydroquinazolin-4(1H)-ones
To a mixture of isatoic anhydride (1.1 mmol), aromatic
aldehyde (1 mmol) and amine (1 mmol), Bi(NO3)3Á5H2O
(0.05 mmol) as catalyst was added. The mixture was heated
at 80 8C for the appropriate time. The progress of the
reaction was monitored by TLC (ethyl acetate/n-hexane,
1:3). After completion of the reaction, hot ethanol (15 mL)
was added and the catalyst was removed by filtration. The
pure 2,3-disubstituted 2,3-dihydroquinazolin-4(1H)-one
was obtained by recrystallization from ethanol.
2. Experimental
2.3. General procedure for the synthesis of 2,3-disubstituted
quinazolin-4(3H)-ones
2.1. General
After completion of the reaction for producing 2,3-
Melting points were obtained by Stuart Scientific SMP2
apparatus and are uncorrected. Yields refer to isolated
products. IR spectra were recorded on FT-IR Nicolet 400D.
1H and 13C NMR (500 and 125 MHz) spectra were recorded
on a Bruker-Avance AQS 500 spectrometer. Mass spectra
disubstituted
2,3-dihydroquinazolin-4(1H)-one
(4),
Bi(NO3)3Á5H2O (0.65 mmol) was added to the reaction
mixture. The mixture was heated at 100 8C for the
appropriate time. The reaction progress was monitored
Scheme 2. Synthesis of 2,3-dihydroquinazolin-4(1H)-ones and quinazolin-4(3H)-ones.

946
I. Mohammadpoor-Baltork et al. / C. R. Chimie 14 (2011) 944–952
by TLC (ethylacetate/n-hexane, 1:5). At the end of the
reaction, hot ethanol (15 mL) was added and the mixture
was filtered. The pure 2,3-disubstituted quinazolin-4(3H)-
one was obtained by recrystallization from ethanol.
conveniently obtained by recrystallization from ethanol.
Owing to the mild reaction conditions, several functional
groups such as NO2, CN, OMe and C=C bond were found to
be compatible. All these results clearly showed the
efficiency of this catalytic system in the synthesis of 2,3-
disubstituted 2,3-dihydroquinazolin-4(1H)-ones.
3. Results and discussion
3.2. Synthesis of 2,3-disubstituted quinazolin-4(3H)-ones
3.1. Synthesis of 2,3-disubstituted 2,3-dihydroquinazolin-
4(1H)-ones
It is noteworthy that in the synthesis of 2-(4-
chlorophenyl)-3-ethyl-2,3-dihydroquinazolin-4(1H)-one
4a, the yield of the product was reduced by increasing the
temperature and or by increasing the amount of
Bi(NO3)3Á5H2O (Table 1, entries 4–10). Under these
conditions, in addition to 4a, 2-(4-chlorophenyl)-3-ethyl-
quinazolin-4(3H)-one 5a was also produced. Encouraged
by this result, we decided to prepare 2,3-disubstituted
quinazolin-4(3H)-ones 5 by the reaction of isatoic anhy-
dride 1 with aldehydes 2 and amines 3 in the presence of
Bi(NO3)3Á5H2O. In order to determine the best reaction
conditions, the reaction of isatoic anhydride (1.1 mmol)
with ethyl amine (1 mmol) and 4-chlorobenzaldehyde
(1 mmol) in the presence of different amounts of
Bi(NO3)3Á5H2O was investigated. The experimental results
showed that even in the presence of 1 mmol
Bi(NO3)3Á5H2O, the product 5a was obtained in only 75%
yield after 4 h (Table 1, entry 10). In order to improve the
yield, we decided to synthesize 5a via a two-step reaction
(Table 1, entries 11–13). First, the reaction was carried out
with isatoic anhydride, ethyl amine and 4-chlorobenzal-
dehyde in the presence of catalytic amount of
Bi(NO3)3Á5H2O (0.05 mmol) for 1 h at 80 8C. After nearly
complete conversion to the corresponding 2,3-dihydro-
quinazolin-4(1H)-one 4a, as indicated by TLC, 0.65 mmol
Bi(NO3)3Á5H2O was added and the mixture was stirred for a
further 1.5 h at 100 8C. Under these conditions, the desired
product 5a was obtained in 90% yield (Table 1, entry 12).
Higher amounts of the Bi(NO3)3Á5H2O did not improve the
yield of 5a (Table 1, entry 13). Under these conditions,
various aldehydes and amines were reacted with isatoic
anhydride in the presence of Bi(NO3)3Á5H2O and the
corresponding 2,3-disubstituted quinazolin-4(3H)-ones 5
were obtained in high yields (86–95%) (Table 3).
Initially, as a model reaction, the three-component
reaction of isatoic anhydride, ethyl amine and 4-chlor-
obenzaldehyde in the presence of Bi(NO3)3Á5H2O was
investigated under various conditions (Table 1). Different
reaction temperatures and molar ratios of Bi(NO3)3Á5H2O
and reagents were examined. The best yield of the desired
product 4a was obtained by carrying out the reaction with
1.1:1:1:0.05 of isatoic anhydride, ethyl amine, 4-chlor-
obenzaldehyde and Bi(NO3)3Á5H2O at 80 8C for 1 h (Table 1,
entry 3).
With these optimized conditions in hand, the reaction
of isatoic anhydride with a wide range of structurally
varied aldehydes and amines were examined (Table 2).
Aromatic aldehydes containing various electron-donating
and electron-withdrawing groups underwent the conver-
sion smoothly to furnish the corresponding 2,3-disubsti-
tuted 2,3-dihydroquinazolin-4(1H)-ones in excellent
yields (90–97%). It is important to note that the electronic
properties of the substituents on the aromatic aldehydes
had no obvious influence on the yields and reactions times.
Heteroaromatic aldehydes such as 2-thiophenecarbalde-
hyde (Table 2, entries 13 and 21) and 2-pyridinecarbalde-
hyde (Table 2, entry 14) and also
a,b-unsaturated
aldehyde such as cinnamaldehyde (Table 2, entry 15)
afforded the desired products in high yields. The experi-
mental procedure for these transformations is remarkably
simple and requires no toxic organic solvents. After
completion of the reaction, the pure product was
Table 1
Reaction of isatoic anhydride with 4-chlorobenzaldehyde and ethyl
amine in the presence of Bi(NO3)3Á5H2O under solvent-free conditiona.
The efficiency and applicability of this method has
been compared with some of the previously reported
methods in Table 4. As can be seen, the present method is
superior in terms of yield, reaction time and the amount of
catalyst.
Entry
Bi(NO3)3Á5H2O (mmol)
T (8C)
Time (h)
Yield
(%)b
4a
5a
1
2
0.05
40
60
1
40
70
95
90
90
85
80
10
10
15
10
5
0
0
0.05
1
A possible mechanism for these reactions has been
postulated in Scheme 3. First, isatoic anhydride 1 reacts
with amine 2 to afford anthranilamide 6 by removing of
carbon dioxide. Condensation of 6 with aldehyde in the
presence of Bi(NO3)3Á5H2O afforded the intermediate 7.
Bi(NO3)3Á5H2O catalyzes the tautomerization of amide
group and also activates the imine group of this
intermediate which is converted to intermediate 8.
Cyclization of 8 to intermediate 9 via intramolecular
nucleophilic attack of nitrogen to imin carbon followed
by 1,5-proton shift gave the corresponding 2,3-disubsti-
tuted 2,3-dihydroquinazolin-4(1H)-one 4. Finally, the
2,3-dihydroquinazolin-4(1H)-one is oxidized to the
3
0.05
80
1
0
4
0.05
90
1
5
5
0.07
80
1
5
6
0.1
80
1
5
7
0.15
80
1
10
80
85
75
85
90
90
8
0.5
100
100
100
100
100
100
4
9
0.7
4
10
11c
12c
13c
1
4
0.05 + 0.6
0.05 + 0.65
0.05 + 0.7
1 + 1.5
1 + 1.5
1 + 1.5
5
a
Isatoic anhydride (1.1 mmol), ethyl amine (1 mmol) and 4-chlor-
obenzaldehyde (1 mmol).
b
Isolated yield.
c
Reaction was performed in two steps.

I. Mohammadpoor-Baltork et al. / C. R. Chimie 14 (2011) 944–952
947
Table 2
Synthesis of 2,3-disubstituted 2,3-dihydroquinazolin-4(1H)-ones the presence of Bi(NO3)3Á5H2O under solvent-free conditions.
Entry
1
Aldehyde
Amine
EtNH2
Product
Time (h)
1
Yield (%)a
Mp (8C)
132–135 [6]
4a
95
2
3
EtNH2
4b
1
90
97
146–149
EtNH2
4c
1.5
158–161
4
5
EtNH2
4d
4e
2
2
95
96
129–131
EtNH2
160–161 [6]
6
7
EtNH2
EtNH2
4f
1
96
94
176–178 [6]
155–158
4g
1.5
8
9
EtNH2
4h
1
1
91
94
170–172
EtNH2
4i
124–126 [6]
10
11
EtNH2
EtNH2
4j
1
1
93
91
112–116
146–149
4k

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I. Mohammadpoor-Baltork et al. / C. R. Chimie 14 (2011) 944–952
Table 2 (Continued )
Entry
12
Aldehyde
Amine
Product
Time (h)
Yield (%)a
92
Mp (8C)
EtNH2
4l
2
140–143
13
14
EtNH2
EtNH2
4m
4n
1
97
90
126–128
128–130
0.5
15
16
EtNH2
4o
4p
0.5
92
97
132–134
n-BuNH2
1
150–151 [13]
17
18
n-BuNH2
4q
4r
1
94
96
135–138
137–139
n-BuNH2
1.5
19
20
21
n-BuNH2
n-BuNH2
n-BuNH2
4s
4t
1
1
1
95
91
95
102–105
144–146
99–101
4u
22
23
iso-BuNH2
iso-BuNH2
4v
2
2
95
92
128–130
137–139
4w

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949
Table 2 (Continued )
Entry
24
Aldehyde
Amine
Product
Time (h)
Yield (%)a
95
Mp (8C)
iso-BuNH2
4x
4y
2
204–205
25
iso-BuNH2
2
92
65–69
a
Isolated yield.
Table 3
One-pot synthesis of 2,3-disubstituted quinazolin-4(3H)-ones in the presence of Bi(NO3)3Á5H2O under solvent-free conditions.
Entry
1
Aldehyde
Amine
EtNH2
Product
Time (h)
2.5
Yield (%)a
Mp (8C)
5a
90
108–112 [47]
2
3
EtNH2
5b
3
95
94
110–112
101–105
EtNH2
5c
2.5
4
5
EtNH2
5d
5e
3
2
91
92
125–128 [48]
EtNH2
180–184
6
7
EtNH2
5f
4
89
92
190–192 [47]
EtNH2
5g
3.5
125–128

950
I. Mohammadpoor-Baltork et al. / C. R. Chimie 14 (2011) 944–952
Table 3 (Continued )
Entry
8
Aldehyde
Amine
Product
Time (h)
2.5
Yield (%)a
93
Mp (8C)
n-BuNH2
n-BuNH2
n-BuNH2
5h
68–70
9
5i
2
92
90
83–85
10
5j
3
123–125
11
12
n-BuNH2
n-BuNH2
5k
5l
2.5
2.5
92
94
62–64
88–90
13
n-BuNH2
5m
2.5
95
117–119
14
15
n-BuNH2
5n
5o
3.5
3.5
87
89
59–61
iso-BuNH2
111–114
16
17
iso-BuNH2
5p
5q
3.5
86
91
Oil
iso-BuNH2
3
109–112

I. Mohammadpoor-Baltork et al. / C. R. Chimie 14 (2011) 944–952
951
Table 3 (Continued )
Entry
18
Aldehyde
Amine
iso-BuNH2
Product
Time (h)
3.5
Yield (%)a
90
Mp (8C)
5r
123–126
a
Isolated yield.
corresponding quinazolin-4(3H)-one 5 in the presence of
Bi(NO3)3Á5H2O.
oxidant. Then, this reaction was performed with Pb(NO3)2;
the absence of any oxidation product proves that NO3 as
À
In order to find the actual role of Bi(NO3)3Á5H2O in the
oxidation of 2,3-dihydroquinazolin-4(1H)-ones, some
reactions were examined under different conditions. It
has been reported that Bi(NO3)3Á5H2O decomposes on
heating [32,46] as shown in Scheme 4.
well as a combination of NO2 and O2 are not the oxidant. On
the other hand, the reaction did not proceed with BiCl3. It is
also noteworthy that less than 5% of the oxidized product
was obtained under argon atmosphere. In addition, regard-
ing to the application of Bi(III)/O2 and Bi(III)/DMSO as
oxidation systems in the literature, we found that most of
thesereactionshavebeencarriedoutinDMSOandCH3CO2H
solvents [31,40–44]. Therefore, the model reaction was
performed in the presence of Bi(NO3)3Á5H2O under these
conditions. The results showed that only 5% and 38% of the
corresponding quinazolin-4(3H)-one was obtained, respec-
On the basis of this reaction, NO3À, NO2, O2, combination
of NO2 and O2, or O2 in the presence of Bi(NO3)3Á5H2O
catalyst may act as key oxidant. First the model reaction was
investigated in only O2 in the absence of Bi(NO3)3Á5H2O; no
oxidation product was obtained under this conditions. This
result clearly showed that O2 alone cannot be the effective
Table 4
Comparison of the results obtained by Bi(NO3)3Á5H2O with some of the preveviously reported reagents.
Entry
Product
Conditions
Time (h)
Yield (%)
1
2
3
SSA (0.15 mmol), H2O, 80 8C [11]
3.5
5
84
80
95
SSA (0.2 mmol), solvent-free, 80 8C [11]
Bi(NO3)3Á5H2O (0.05 mmol), solvent-free, 80 8C
1
4
5
6
KAl(SO4)2Á12H2O (0.4 mmol), EtOH, reflux [6]
KAl(SO4)2Á12H2O (0.52 mmol), H2O, reflux [6]
Bi(NO3)3Á5H2O (0.05 mmol), solvent-free, 80 8C
5
1
1
80
70
94
7
8
9
p-TsOH (0.5 mmol), H2O, reflux [8]
1
3
1
90
82
96
p-TsOH (0.5 mmol), EtOH, reflux [8]
Bi(NO3)3Á5H2O (0.05 mmol), solvent-free, 80 8C
Scheme 3. Proposed mechanism.

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I. Mohammadpoor-Baltork et al. / C. R. Chimie 14 (2011) 944–952
Scheme 4. Decomposition of Bi(NO3)3Á5H2O on heating.
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under solvent-free conditions is more convenient for the
oxidation of 2,3-dihydroquinazolin-4(1H)-ones to their
corresponding quinazolin-4(3H)-ones. All these observa-
tions indicate that the presence of oxygen is essential and
Bi(NO3)3Á5H2O has some catalytic effect in this oxidation
reaction. Therefore, a combination of Bi(NO3)3Á5H2O along
with oxygen which is produced by the decomposition of this
reagent and also provided from air acts as actual oxidizing
system in these reactions.
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In conclusion, we have demonstrated for the first
time that Bi(NO3)3Á5H2O could be used as an efficient
catalyst for the selective synthesis of 2,3-disubstituted
2,3-dihydroquinazolin-4(1H)-ones and their one-pot
oxidation to quinazolin-4(3H)-ones under solvent-free
conditions. In addition, the advantages including high
yields, short reaction times, easy work-up, green
procedure avoiding toxic organic solvents, and the use
of readily available, inexpensive and relatively non-toxic
catalyst make the present method superior to the
existing methods for the synthesis of quinazolinone
derivatives.
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