Iodine: Selectively promote the synthesis of mono substituted quinazolin-4(3H)-ones and 2,3-dihydroquinazolin-4(1H)-ones in one-pot

Article abstract of DOI:10.1002/jhet.414

(Chemical Equation Presented) A general and versatile one-pot three-component procedure for the selective synthesis of mono substituted quinazolin-4(3H)-ones and 2,3-dihydroquinazolin-4(1H)-ones were described. The selectivity could be controlled by the ratio of iodine concentration.

Full text of DOI:10.1002/jhet.414

September 2010
Iodine: Selectively Promote the Synthesis of Mono Substituted
Quinazolin-4(3H)-ones and 2,3-Dihydroquinazolin-4(1H)-ones
in One-Pot
1035
Li-Yan Zeng and Chun Cai*
Chemical Engineering College, Nanjing University of Science and Technology,
Nanjing, Jiangsu 210094, China
*E-mail: c.cai@mail.njust.edu.cn
Received September 6, 2009
DOI 10.1002/jhet.414
Published online 13 July 2010 in Wiley Online Library (wileyonlinelibrary.com).
A general and versatile one-pot three-component procedure for the selective synthesis of mono substi-
tuted quinazolin-4(3H)-ones and 2,3-dihydroquinazolin-4(1H)-ones were described. The selectivity could
be controlled by the ratio of iodine concentration.
J. Heterocyclic Chem., 47, 1035 (2010).
INTRODUCTION
ones. Although Chen reported quinazolin-4(3H)-ones
could be obtained by employing DMSO as solvent
instead of EtOH, which was utilized to prepare 2,3-dihy-
droquinazolin-4(1H)-ones in the same protocol [23],
novel flexible strategies for selective synthesis of 2,3-
dihydroquinazolin-4(1H)-ones and quinazolin-4(3H)-ones
without toxicity, unavailable or expensive agent should
benefit both synthetic and medicinal chemistry in terms
of Green Chemistry.
2,3-Dihydroquinazolin-4(1H)-ones are an important
class of heterocycles with a broad spectrum of biological
and pharmaceutical activities, such as antitumor, analge-
sic, anticancer, and diuretic [1–3]. Traditional procedure
for the synthesis of these compounds involves the con-
densation of anthranilamides, as well as the reductive
cyclization of o-nitrobenzamide or o-azidobenzamide
with aldehydes or ketones in the presence of Brunsted or
Lewis acid catalyst [4–12]. On the other hand, quinazo-
lin-4(3H)-ones, the oxidized products of 2,3-dihydroqui-
nazolin-4(1H)-ones [13], were important precursors for
the synthesis of natural and pharmacological compounds
including febrifugine and isofebrifugine [14]. It can also
be obtained by the cyclization of anthranilamides with
aldehyde and other similar methods [15]. With the one-
pot multicomponent reactions (MCRs) emerged as a
powerful tool to routinely find out novel biologically
active compounds [16], recently, various approaches to
2,3-dihydroquinazolin-4(1H)-ones and quinazolin-4(3H)-
ones, promoted by Brunsted or Lewis acid, or by sup-
ported acid with the help of special instrument, were
explored independently in a one-pot three-component
protocol starting from isatoic anhydride A, primary
amine, and aldehyde [17–23]. However, there is a paucity
of efficient synthetic route to implement the selectivity of
two such compounds, an extra-oxidize step was always
required to complete the fusion of the quinazolin-4(3H)-
As an oxidant, iodine is widely used for the oxidation
of alcohols, aldehydes, sulfides, and amines; for the oxi-
dation to aromatics; for the introduction of protecting
groups; for the deprotection, and so on [24]. Meanwhile,
iodine has a wide range of application as a mild Lewis
acid catalyst in organic synthesis, such as the Michael
addition, the mannich reaction, the hantzsch reaction
and many other transformations [25,26]. However, a lit-
erature survey suggested that few studies have been per-
formed on applying both the oxidizing and catalyzing
abilities of iodine simultaneously to organic functional
group conversions. As a cheap, less toxic, easily accessi-
ble, and eco-benign reagent, iodine would be more prac-
tical for organic synthesis if the selectivity could be
controlled quantificationally via modulating the ratio in
as much as the oxidizing ability require more iodine to
fulfill. Herein, we would like to disclose a versatile pro-
cedure for the fabrication of mono substituted quinazo-
lin-4(3H)-ones and 2,3-dihydroquinazolin-4(1H)-ones
selectively in the presence of different ratio of iodine.
C
V
2010 HeteroCorporation

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L.-Y. Zeng and C. Cai
Vol 47
Table 1
The optimization of reaction conditions to synthesis 2-(4-methoxylphenyl)quinazolin-4(3H)-one and
2-(4-methoxylphenyl)-2,3-dihydroquinazolin- 4(1H)-one.a
Entry
I2 (mol %)
Solvent
A/AcONH4
t (min)
Yield (%)b
M1/N1c
1
2
20
20
20
20
20
25
20
15
10
5
EtOH
H2O
1:1.2
1:1.2
1:1.1
1:1.3
1:1.5
1:1.2
1:1.2
1:1.2
1:1.2
1:1.2
1:1.2
25
15
86
77
81
85
85
86
85d
91
90
89
23
100/0
100/0
100/0
100/0
100/0
100/0
100/0
97/3
3
4
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
40
30
5
6
30
25
7
8
25
60
9
120
70
24h
48/52
1/99
0/100
10
11
0
a Reaction conditions: 4-methoxylbenzaldehyde(5 mmol), was added to the solution containing A(5mmol), iodine, and AcONH4 at room tempera-
ture, which was then increased to refluxing temperature.
b Isolated yield of M1 and N1 mixture.
c Determined by LC-MS.
d N2 was used.
RESULTS AND DISCUSSION
with the iodine concentration decreased from 20 mol %
(Table 1, Entries 6–9), the pure product N1 could not be
obtained until the amount of iodine reduced to 5 mol %,
which was the right concentration to catalyze this three-
compound reaction to give product N1, more iodine
may present the oxidizing ability, resulting in mixed
products of M1 and N1 (Table 1, Entries 8 and 9). As
all the reactions were exposed in air, the O2 may play
the role of oxidant in the preparation of M1, so we
employed the N2 as an inert gas to perform the reaction
(Table 1, Entry 7), and found that only the oxidated
product M1 was detected in the reaction mixture by LC-
Ms, which indicate that the catalytic iodine (20 mol %)
played the roles of both catalyst and oxidant. Prelimi-
nary results unprecedentedly implied that we can selec-
tively construct the structure of M1 and N1 promoted
by 20 and 5 mol % of iodine, respectively.
Following our continued interest in the iodine-cata-
lyzed MCRs [26a–d], 20 mol % of iodine was initially
selected to catalyze the model reaction of isatoic anhy-
dride, 1.2 equiv. of ammonium acetate, and 4-methoxy-
benzaldehyde in refluxing ethanol, aimed at obtaining
the compound N1. After 40 min stirring, the white flocs
were totally precipitated from the reaction solution, the
final pure product yielded in 63% after work up, unex-
pectedly melted at 241ꢀC, which is the melt point of
compound M1 exactly. Subsequent 1H NMR and LC-
MS analysis certified that the white floc was just M1.
Therefore, the optimization of the reaction conditions
was carried out. First, the addition order of reactants
was considered. As the enamine could be formed in situ
and thus influence the yield of desired product, the alde-
hyde was added at last to the stirring solution at room
temperature, which was increased to refluxing tempera-
ture as soon as possible, to our delight, the yields of
product M1 could be up to 86%. With these conditions
in hand, the solvent, ratio of A and AcONH4, and the
iodine concentration were screened subsequently. The
results in Table 1 showed that refluxing the A, 4-
methoxylbenzaldehyde and AcONH4 rationed at 1:1:1.2
in the presence of 20 mol % of iodine about 25 min
would provide the best result. Increasing the iodine
amounts was ineffective for improvement of final yields.
Interestingly, product N1 was detected and increased
In a comprehensive study, a sampling of the aldehydes
was employed to explore the scope of this one-pot three-
component reaction under optimal conditions (Table 2).
Generally, all of the aldehydes participated smoothly and
afforded the desired products in good to excellent yields,
except for the 4-nitrobenzaldehyde yielded in 77% of M
and 56% of N (Table 2, Entry 9 and 15). According to
LC-MS monitoring of reaction mixtures, the benzylalde-
hyde and aromatic aldehydes bearing 4-Cl, 2-Cl, 4-Br
demand more iodine to furnish the pure product M (Table
2, Entry 2, 4, 5, 8). The reaction time was slightly
extended in the cases of producing pure product N.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

September 2010
Iodine: Selectively Promote the Synthesis of Mono Substituted
Quinazolin-4(3H)-ones and 2,3-Dihydroquinazolin-4(1H)-ones in One Pot
1037
Table 2
The preparation of 2-substituted-quinazolin-4(3H)-ones and 2-substituted-2,3-dihydroquinazolin- 4(1H)-ones.a
Entry
R
I2 (mol %)
t (min)
Yield (%)b
M/Nc
1
2
4-OMe
4-Cl
20
20
25
20
20
25
30
20
30
20
20
20
30
20
5
25
40
86
90
91
81
87
89
83
94
93
92
81
89
87
77
89
82
95
91
91
56
100/0
98/2
25
150
90
65
45
60
45
100/0
100/0
1/99
84/16
100/0
3/97
3
4
4-OH
H
5
2-Cl
99/1
6
7
8
4-N(Me)2
3-Cl
4-Br
15
20
100/0
100/0
2/98
99/1
100
60
30
9
10
11
12
13
14
15
4-NO2
4-OMe
H
90
70
1/99
1/99
5
100
55
120
90
4-Cl
5
5
0/100
0/100
0/100
0/100
4-N(Me)2
4-Br
4-NO2
5
5
600
a Reaction conditions: 1 equiv. of aldehyde(5 mmol) was added to the solution containing A(5 mmol), iodine, and 1.2 equiv. of AcONH4(5 mmol)
at room temperature, which was then increased the to refluxing temperature.
b Isolated yield
c Determined by LC-MS
Besides, benzylaldehyde and 3-chlorobenzaldehyde pro-
vide somewhat lower yields and probable reason for this
may be the lack of electron-influence.
EtOH, we chose EtOH as the solvent to exam other repre-
sentative aromatic amine. As shown in Table 3, all of the
substrates were compatible and the aromatic amine pos-
sessing electron-withdrawn group would lead to longer
reaction time and slightly lower yield (Table 3, Entry 3).
In conclusion, we have developed a novel and versatile
method for the first time to selectively synthesize 2-sub-
stituted-quinazolin-4(3H)-ones and 2-substituted-2,3-
dihydroquinazolin-4(1H)-ones from isatoic anhydride,
primary amine and various aldehydes in one-pot MCR
protocol via modulating the iodine concentration, and
also prepared 3-substituted-quinazolin-4(3H)-ones under
the same conditions in the presence of 5 mol % of iodine.
All of the reactions provided good to excellent yields of
products that could be crystallized from the reaction solu-
tion. The operational simplicity, conditional generality,
electively controllability made this method attractive to
extensive application in organic chemistry.
Encouraged by these successes, we evaluated
orthoester and p-toluidine for the MCR performance to
furnish 3-substituted quinazolin-4(3H)-ones E and 2,3-
dihydroquinazolin-4(1H)-ones F under the same condi-
tions. Fortunately, the desired product 3-p-tolylquinazo-
lin-4(3H)-one was favourably generated in 78% yield
(Table 3, Entry 1). Thereafter, 5 mol % of iodine was
tested aiming at constructing the structure 3-p-tolylquina-
zolin-2,3-dihydroquinazolin-4(1H)-one
F
(Fig. 1),
whereas the same product 3-p-tolylquinazolin-4(3H)-one
was obtained again in a 99% LC yield (Table 3, Entry 2).
After carefully literature search, it was found that all of
the methods reported [9,10,21] starting from orthoester
were apt to form quinazolin-4(3H)-ones, for this may be
the potential hydrogen-acquiring ability of AOEt dissoci-
ated from orthoester. Further attempt to optimize the con-
ditions suggested that increasing the amount of amine up
to 1.5 equiv. and replace the EtOH with H2O could
improve the yield up to 89% and shorten the reaction
time. As the pure product should be crystallized from
EXPERIMENTAL
The isatoic anhydride and iodine were obtained from commer-
cial suppliers and used without further purification. All of the
1
products are known and their physical data, mass data, and H
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

1038
L.-Y. Zeng and C. Cai
Vol 47
Table 3
The preparation of 3-substituted-quinazolin-4(3H)-ones.a
Entry
R0
Solvent
I2 (mol %)
t (min)
Yield (%)b
1
4-Me
EtOH
EtOH
EtOH
EtOH
H2O
EtOH
EtOH
EtOH
20
5
25
30
78
75
c
5
5
60
25
74.
d
88.
89
93
81
84
5
5
15
25
2
3
4
4-OMe
4-Cl
H
5
200
55
5
a Reaction conditions: 1 equiv. of othoester(5 mmol) was added to the solution containing A(5 mmol), iodine, and aromatic amine at room tempera-
ture, which was then increased the to refluxing temperature.
b Isolated yield.
c 1 equiv. of p-toluidine was added.
d 1.5 equiv. of p-toluidine was added.
NMR were essentially identical with those of authentic samples.
Mass spectra were taken on an Agilent LC-MS 1100 series
1
instrument in the electrospray ionization (positive ESI) mode. H
The 2-substituted-2,3-dihydroquinazolin-4(1H)-ones N were
synthesized by a similar procedure except that 5 mol % of
iodine(0.063 g, 0.25 mmol) was used. The products N
NMR spectra were recorded at 300 MHz in DMSO-d6, and
chemical shifts were reported in ppm from internal TMS (d).
The typical procedure for the preparation of 2-substi-
tuted-quinazolin-4(3H)-ones M. 4-methoxylbenzaldehyde
(0.68 g, 5 mmol), was added to the stirring solution containing
were white flake. 2-(4-Methoxyphenyl)-2,3-dihydroquinazolin-
4(1H)-one (Table 2, Entry 12): 1H NMR(300 MHz, DMSO-
d6) d 3.73 (s, 3H), 5.68 (s, 1H), 6.66–6.74 (m, 2H), 6.92 (d,
2H), 6.94 (s, NH), 7.23 (m, 1H), 7.39–7.41 (d, 2H), 7.58–7.60
(d, 1H), 8.21 (s, NH); MS (ESþ) m/z 255(M þ H); 2-(4-Chlor-
ophenyl)-2,3-dihydroquinazolin-4(1H)-one (Table 2, Entry 12):
1H NMR(300 MHz, DMSO-d6) d 5.78 (s, 1H), 6.69–6.77 (m,
2H), 7.16 (s, NH), 7.22–7.28 (m, 1H), 7.44–7.53 (m, 4H),
7.60–7.63 (m, 1H), 8.36 (s, NH); MS (ESþ) m/z 259(M þ H).
The typical procedure for the preparation of 3-substi-
tuted-quinazolin-4(3H)-ones E. Orthoester (5 mmol) was
injected slowly into the stirring solution of A(0.815 g, 5
mmol), iodine(0.063 g, 0.25 mmol) and p-toluidine (0.8 g, 7.5
mmol) in EtOH at room temperature, increasing the tempera-
ture and refluxing the mixture 25 min followed by adding hot
ethanol to further dissolve the solid formed, the product E was
precipitated from the homogeneous solution slowly with the
temperature decreased. Simple filtration and dryness would
afford the pure 3-p-tolylquinazolin-4(3H)-one (1.04 g, 88%,
A(0.815 g,
5 mmol), iodine(0.253 g, 1 mmol), and
AcONH4(0.462 g, 6 mmol) at room temperature in EtOH, then
refluxing the mixture, after 25 min the white solid precipitated
and EtOH was added till the solid dissolved again. The mix-
ture was cooled to room temperature and the white flocs were
crystallized slowly. After simple filtration and dryness, the
product M1 was yielded in 86% (1.09 g, white flocs, m.p.
241ꢀC). 2-(4-Methoxyphenyl)quinazolin-4(3H)-one (Table 2,
1
Entry 1): H NMR(300 MHz, DMSO-d6) d 3.81 (s, 3H), 7.04–
7.07 (d, 2H), 7.42–7.47 (m, 1H), 7.65–7.68 (d, 1H), 7.76–7.78
(m, 1H), 8.08–8.11 (d, 1H), 8.14–8.17 (d, 2H), 12.53 (br s,
NH); MS (ESþ) m/z 253(M þ H); 2-(4-Chlorophenyl)quinazo-
1
lin-4(3H)-one (Table 2, Entry 2): H NMR(300 MHz, DMSO-
d6) d 7.52–7.57 (m, 1H), 7.62–7.65 (m, 2H), 7.74–7.76 (d,
1H), 7.83–7.88 (m, 1H), 8.15–8.22 (m, 3H), 12.83 (br s, NH);
MS (ESþ) m/z 257(M þ H).
1
white solid, m.p. 146–148ꢀC) (Table 3, Entry 1): H NMR(300
MHz, DMSO-d6) d 2.40 (s, 3H), 7.35–7.44 (m, 4H), 7.57–7.62
(m, 1H), 7.73–7.76 (d, 1H), 7.85–7.91 (m, 1H), 8.19–8.21 (d,
1H), 8.32 (s, 1H); MS (ESþ) m/z 237(M þ H); 3-(4-Methoxy-
phenyl)quinazolin-4(3H)-one (Table 3, Entry 2): 1H
NMR(300MHz, DMSO-d6) d 3.83 (s, 3H), 7.09–7.12 (m, 2H),
7.45–7.48 (m, 2H), 7.57–7.62 (m, 1H), 7.73–7.75 (m, 1H),
7.85–7.91 (m, 1H), 8.18–8.21 (m, 1H), 8.31 (s, 1H); MS
(ESþ) m/z 253(M þ H).
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Figure 1. The expected structure 3-p-tolylquinazolin-2,3-dihydroquina-
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

September 2010
Iodine: Selectively Promote the Synthesis of Mono Substituted
Quinazolin-4(3H)-ones and 2,3-Dihydroquinazolin-4(1H)-ones in One Pot
1039
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet