Environmentally friendly synthesis of 2-aryl-2,3-dihydroquinazolin-4(1H)- ones by novel Co-CNTs as recoverable catalysts

Article abstract of DOI:10.1016/j.crci.2013.06.007

The objective of this study is to investigate the possibility of using Co-CNTs as a green reaction medium and a catalyst for the cyclo-condensation of o-aminobenzamide with various aldehydes. This inexpensive, non-toxic, and readily available catalyst efficiently catalyzes the above condensation for the synthesis of 2-aryl-2,3-dihydroquinazolin-4(1H)-ones. Compared to the classical reaction, this is a simple, highly yielding, time saving, and environmentally friendly method.

Full text of DOI:10.1016/j.crci.2013.06.007

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´
Full paper/Memoire
Environmentally friendly synthesis of 2-aryl-2,3-
dihydroquinazolin-4(1H)-ones by novel Co-CNTs as
recoverable catalysts
*
Javad Safari , Soheila Gandomi-Ravandi
Laboratory of Organic Compound Research, Department of Organic Chemistry, College of Chemistry, University of Kashan, PO Box 87317,
51167 Kashan, Islamic Republic of Iran
A R T I C L E I N F O
A B S T R A C T
Article history:
The objective of this study is to investigate the possibility of using Co-CNTs as a green
reaction medium and a catalyst for the cyclo-condensation of o-aminobenzamide with
various aldehydes. This inexpensive, non-toxic, and readily available catalyst efficiently
catalyzes the above condensation for the synthesis of 2-aryl-2,3-dihydroquinazolin-
4(1H)-ones. Compared to the classical reaction, this is a simple, highly yielding, time
saving, and environmentally friendly method.
Received 30 January 2013
Accepted after revision 11 June 2013
Available online xxx
Keywords:
Co-CNT nanocomposites
o-Aminobenzamide
Dihydroquinazolin-4(1H)-one
Green chemistry
ß 2013 Acade´mie des sciences. Published by Elsevier Masson SAS. All rights reserved.
1. Introduction
reaction. Therefore, the development of a clean, high
yielding and eco-friendly approach is highly desirable. In
Heterocyclic chemistry occupies an important place in
organic chemistry research worldwide [1–4] and forms the
basis of many pharmaceutical, agrochemical and veter-
inary products. Especially, 2,3-dihydro-2-aryl-4(1H)-qui-
nazolinones are a class of fused heterocycles that have
drawn much attention due to their potentially biological
and pharmaceutical activities as anti-tumor, diuretic, and
herbicidal agents, as well as plant growth regulators [5].
Three-component reaction of isatoic anhydride, aldehyde
and amine [6–10], reduction cyclization of o-nitrobenza-
mides and orthoformate, aldehydes or ketones [11] and
reduction of quinazolin-4(3H)-ones [12] are also reported
for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones.
However, most of the reported methods suffer from some
limitations, such as long reaction times, harsh reaction
conditions, low yields, tedious work-up and multi-step
recent years, the development of efficient and environ-
mentally benign chemical processes or methodologies for
widely used recyclable catalysts and unharmful solvents
has been one of the major challenges for chemists in
organic synthesis [13].
Cobalt is an important non-ferrous metal and is
extensively applied in various processes due to its high
activity and low cost. The unique characteristics of cobalt
metal, especially its magnetic properties, make it attractive
in wide fields, such as data information storage [14],
recording devices, magnetic refrigeration, including bio-
medical systems [15], magnetic alloys, high-temperature
alloys, cemented carbides, and catalysts [16]. The support
plays a significant role in dispersion, reducibility changes,
and catalytic behaviour of active cobalt metal [17–19]. In
order to achieve high-surface active sites, supported cobalt
catalysts were known to be highly active for various
supports, including silica, alumina, titania, magnesia,
kieselguhr, and zeolite [17,20–27]. A limitation of some
of these support materials is their reactivity toward cobalt
*
Corresponding author.
E-mail address: Safari@kashanu.ac.ir (J. Safari).
1631-0748/$ – see front matter ß 2013 Acade´mie des sciences. Published by Elsevier Masson SAS. All rights reserved.
http://dx.doi.org/10.1016/j.crci.2013.06.007
Please cite this article in press as: Safari J, Gandomi-Ravandi S. Environmentally friendly synthesis of 2-aryl-2,3-
dihydroquinazolin-4(1H)-ones by novel Co-CNTs as recoverable catalysts. C. R. Chimie (2013), http://dx.doi.org/
10.1016/j.crci.2013.06.007

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H
H
N
NH2
O
Co-CNTs
O
R
+
NH2
Solvent free
NH
R
O
3
2
1
Scheme 1. Co-CNT-catalyzed green synthesis of 2-aryl-2,3-dihydroquinazolin-4(1H)-ones.
for the formation of mixed compounds that are reducible
only at high reduction temperatures [20–23]. To avoid
these problems, the use of activated carbon as a catalyst
support has been reported. The metal–carbon interaction
is not so strong and the cobalt catalyst can therefore be
completely reduced [28–30]. On the other hand, interac-
tions of CNTs with metal particles have been the topic of
current investigations. The studies have pointed out that
their special and steady structural characteristics and
morphology are quite suitable for use as catalyst support
materials [29–34]. Especially, carbon nanotubes (CNT) as
support exhibit superior catalytic activity due to the fact
they prevent the congregation of nanoparticles and
enhance the catalytic active sites. Also, CNTs in the
nanocomposites can provide continuous conducting path-
ways for faster electron transfer [35]. Therefore, the
combination of Co NPs with CNTs has attracted consider-
able interest for their wide applications in the fields of
catalysis. We herein disclose a novel, highly efficient
condensation of the appropriate derivatives of aldehyde
with o-aminobenzamide using Co-CNT as a catalyst and
solvent for the preparation of 2-aryl-2,3-dihydroquinazo-
lin-4(1H)-ones under solvent-free conditions (Scheme 1).
To the best of our knowledge, this is the first report dealing
with the eco-friendly formation of a 2-aryl-2,3-dihydro-
quinazolin-4(1H)-one heterocyclic system using this
catalytic system.
new selective method for the synthesis of 2-aryl-2,3-
dihydroquinazolin-4(1H)-ones using cobalt/multi-walled
carbon nanotube as the catalysts. The results obtained
from the Co-supported-catalyzed synthesis of 2-aryl-2,3-
dihydroquinazolin-4(1H)-ones (3a-j) from cyclo-conden-
sation of o-aminobenzamide with various aldehydes under
solvent-free conditions are summarized in Table 1. Indeed,
in order to evaluate the novelty and impact of the result, a
comparison catalytic test with
a commercial Co/AC
catalyst is carried out. As shown in Table 1, Co-CNTs can
act as high-efficiency catalysts with short reaction times
and high yields of the obtained products. In general, the
main advantages of CNT supports compared to activated
carbon (AC) are the high purity of the material, which can
avoid self-poisoning, exceptionally high mechanical
strength, medium to high specific surface areas, high
thermal conductivity, high external surface area, and
specific metal support interactions that can directly affect
the catalytic activity, the full accessibility of the reactants
to the active sites, and selectivity [36]. From the data in
Table 1, it can be concluded that the presence of the
electron-withdrawing substituents on the aromatic ring
can increase the reaction rate and, as a result, the reaction
times are shortened and the yields are increased while the
electron-donating substituents have diverse effects. The
reaction of o-aminobenzamide with benzaldehyde as a
model experiment was examined during different times to
determine the optimal reaction time (Fig. 1). Then, we
examined the effect of the molar amounts of catalyst
employed in this cyclo-condensation (Table 2). Finally, the
recyclability of the catalyst was investigated. For this
purpose, the reaction of anthranilamide and benzaldehyde
in ethanol and in the presence of Co-CNT was investigated.
After the reaction was complete (monitored by TLC),
2. Results and discussion
As part of our interest in the synthesis of heterocyclic
compounds and due to the present awareness of applying
environmentally benign strategies in organic synthesis, we
started a series of studies aimed at the development of a
Table 1
Catalytic effect of Co-supported catalysts in cyclization of o-aminobenzamide with various aromatic aldehydes.
Entry
R
Product
Co-CNTs
Co-AC
Mp (8C)
Time (min)/Yield (%)
Time (min)/Yield (%)
Found
Reported
1
2
3
4
5
6
7
8
9
10
H
3a
3b
3c
3d
3e
3f
8/96
20/88
5/92
25/52
35/46
20/55
40/59
35/40
30/58
22/50
20/49
30/54
40/46
216–218
279–280
196–198
184–186
181–183
205–206
225–227
250–252
264–266
225–226
217–219 [37]
278–280 [8]
195–196 [37]
186–187 [8]
182–184 [38]
206–207 [37]
224–226 [37]
249–251 [39]
266–267 [8]
225–227 [40]
4-OH
3-NO2
2,4-(OMe)2
4-OMe
4-Cl
17/95
15/85
12/91
6/95
4-Me
3g
3h
3i
4-CN
5/89
3-F
12/93
20/87
2-Naphthyl
3j
Please cite this article in press as: Safari J, Gandomi-Ravandi S. Environmentally friendly synthesis of 2-aryl-2,3-
dihydroquinazolin-4(1H)-ones by novel Co-CNTs as recoverable catalysts. C. R. Chimie (2013), http://dx.doi.org/
10.1016/j.crci.2013.06.007

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Fig. 1. Effect of time on the preparation of compound 3a.
Fig. 2. Reuse of Co-CNT for the synthesis of compound 3a.
followed by filtration, the filtrate was saved for the next
reaction. When the same reaction was performed in this
filtrate containing the used catalyst, lower yields (94%) of
the product were obtained. According to the same
procedure, the recyclability in the next runs was examined
under the same conditions. It could result from a loss of
catalyst while the filtration was conducted. The results of
this study are presented in Fig. 2.
picture of the composites displays more efficiently the
small cobalt particles outside the tubes. The particles
inside the tubes are fairly uniform; this is due to the fact
that CNT channels have regulated the growth of the metal
particles inside the tubes [44] (Fig. 3).
Fig. 4 presents the XRD patterns of CNT-COOH and Co/
CNT composites. In the XRD spectrum of the acid treated
CNTs, the diffraction peak at 25.928 is assigned to the
(002) plane of CNTs, while the other peaks in the
spectrum of the composite are related to different crystal
planes of Co. The diffraction peaks at 45.168, 48.198 and
76.648 are attributed to the (100), (101), and (220) planes
of the hexagonal-phase structure of cobalt, and the peak
at 50.368 corresponds to the (200) crystal plane of the
cubic structure. This indicates that the structure of the Co
nanoparticle-decorated CNTs is a mixture of hexagonal
and cubic phases. In addition, the peak broadening
indicates that the size of the Co nanoparticles is
significantly small.
According to the evolution of the reaction conditions as
well as to other reported mechanisms in the literature, a
possible mechanism for the synthesis of these products is
presented in Scheme 2. It is proposed that, at first, the
intermediate I is formed through the nucleophilic attack of
the amino group in 2-aminobenzamide at the activated
carbonyl group of the aldehyde by the metal as a supported
catalyst. Also, the part of amide in the imine intermediate I
is converted into its tautomer in the presence of a catalyst.
Then, the Schiff-base intermediate II is produced by
dehydration of the intermediate I. Then, the intramole-
cular nucleophilic addition reaction between the amide
group nitrogen and the activated Schiff base carbon gives
the intermediate III and is followed by a 1,5-proton
transfer, affording the products.
Thus, the Co-CNT nanocomposites also exhibit
a
significant catalytic effect under solvent-free conditions
for the synthesis of 2-aryl-2,3-dihydroquinazolin-4(1H)-
one derivatives with short reaction times. The advantage of
this synthesis route is its application to parallel synthesis
that permits an easy and rapid access to a large number of
derivatives for biological evaluation as well as potential
chemotherapeutic agents. The spectral data, structures and
purity of these compounds were confirmed by IR and (1H
and 13C) NMR and were in complete agreement with the
reported data. In each case, the target product was
obtained in excellent yield and with a high degree of
purity.
A cobalt sample supported on CNTs was analyzed by
TEM and SEM. The TEM images of the supported catalyst
revealed that the dark spots represent the cobalt, which
was distributed inside the tubes and also on the outer
surface of the CNTs. This can be attributed to the tubular
morphology of graphene layers, which can induce
capillary forces during the impregnation process. The
most of the CNTs have been completely decorated with Co
nanoparticles. Also, the distribution of Co nanoparticles
inside the tubes is quite uniform and no local aggregation
is detected. It is known that the exterior surfaces of
the CNTs are electron-enriched, while the interior ones
are electron-deficient [41–43], which could influence the
structure and electronic properties of the substrates in
contact with either surface. The scanning electron
microscopy (SEM) picture reveals that nanotubes are
completely covered with the supporting materials and
that there are no other impurities. In addition, the SEM
3. Experimental
All the chemicals were obtained from Merck Company
and used as received. MWNTs were purchased from
Nanotech Port Co. (Taiwan). These MWNTs were pro-
duced via the chemical vapor deposition (CVD, or
sometimes called catalytic pyrolysis) method. The outer
diameter of CNT was between 20 and 40 nm. Melting
points (8C) were determined on an Electrothermal MK3
apparatus using an open-glass capillary and are uncor-
rected. The IR spectra were obtained with a PerkinElmer
Table 2
Optimization of the molar amounts of catalyst for compound 3a.
Catalyst (g)
0.001
0.003
0.005
0.008
0.01
Time (min)
Yield (%)
25
81
20
87
14
90
8
8
96
96
Please cite this article in press as: Safari J, Gandomi-Ravandi S. Environmentally friendly synthesis of 2-aryl-2,3-
dihydroquinazolin-4(1H)-ones by novel Co-CNTs as recoverable catalysts. C. R. Chimie (2013), http://dx.doi.org/
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Fig. 3. TEM image of cobalt supported on acid-treated CNTs (a); SEM image Co-CNTs composites (b).
FT–IR 550 spectrophotometer (KBr pellets). 1H and 13C
NMR spectra were recorded using a Bruker DRX–400
spectrometer and chemical shifts ( ) are reported in ppm
d
downfield from an internal TMS standard. ESI–MS was
recorded on a Micromass Quattro II triple-quadrupole
mass spectrometer. Microwave oven reactions were
performed on a CEM–Discover Focused Monomode, with
a microwave input power of 300 W and a microwave
frequency of 2450 MHz. The purity of the compounds and
the completion of the reactions were monitored by thin
layer chromatography (TLC) on silica gel plates in the
solvent system petroleum ether–EtOAc (V/V = 1:1). Ele-
mental analysis was determined by a Heraeus CHN-O-
RAPID elemental analyzer. The structure of the products
was also confirmed by conventional techniques (1H and
13C NMR). XRD patterns were obtained on a Holland
Philips Xpert X-ray powder diffraction (XRD) diffract-
ometer (Cu K
a radiation, l = 0.154056 nm), at a scanning
Fig. 4. X-Ray diffraction pattern of acid treated CNTs and CNT/Co
speed of 28/min from 108 to 1008 (2u). SEM images were
nanocomposites.
Co-CNT
HO
H
N
OH
Co-CNT
O
N
O
H
Ar
Co-CNT
+
Co-CNT
HO
N
Ar
H
NH2
NH2
I
H
N
Ar
O
Co-CNT
H
OH
II
N
H
N
N
H
Ar
N
Ar
III
Scheme 2. Possible mechanism for the formation of dihydroquinazolinone derivatives.
Please cite this article in press as: Safari J, Gandomi-Ravandi S. Environmentally friendly synthesis of 2-aryl-2,3-
dihydroquinazolin-4(1H)-ones by novel Co-CNTs as recoverable catalysts. C. R. Chimie (2013), http://dx.doi.org/
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taken in a FEI Quanta 200 Scanning electron microscope
(SEM), operating at 20 kV. Transmission electron
OH), 6.74 (d, J = 7.6 Hz, 1H, ArH), 6.74 (t, J = 7.6 Hz, 1H, ArH),
5.75 (s, 1H, CH). 13C NMR (100 MHz, DMSO-d6):
d 165.2,
a
microscopy (TEM) micrographs were taken with a Jeol
JEM-2100UHR operating at 200 kV.
149.3, 140.7, 130.4, 129.3, 127.7, 126.2, 125.4, 119.4, 115.0,
114.5, 66.7. HRMS (ESI) for [M+H] found (expected):
240.0895 (240.0898).
3.1. Preparation of the catalyst
3.3.3. 2-(3-Nitrophenyl)-2,3-dihydroquinazolin-4(1H)-one
Co-CNT nanocomposites were prepared according to
the procedures reported in the literature [45]. Briefly, CNTs
were first refluxed at 140 8C for 4 h in concentrated HNO3.
Then, they were filtered out and washed with distilled
water until a neutral pH was reached, and then dried at
120 8C for 8 h. An amount of 0.06 g of oxidized MWCNTs
was dispersed in 100 mL of an ethylene glycol (EG) solution
containing CoCl2 (0.05 M) under sonication. After 10 min,
0.6 g NaOH, 2.65 g Na2CO3, and 3.5 mL N2H4ÁH2O were
added sequentially. Then, the solution was heated in a
microwave oven for 60 s. After that, the product was
washed with distilled water and absolute ethanol, then
dried under vacuum at room temperature.
C
14H11N3O3 (3c)
Light yellow solid; Mp 196–198 8C; Rf = 0.4 (petroleum
ether–EtOAc, 1:1); Anal. calcd. for C14H11N3O3 (%) C 62.45,
H 4.12, N 15.61. Found C 62.53, H 4.14, N 15.54. IR (KBr,
cmÀ1): 3337 (NH), 3146 (NH), 1673 (C5O), 1635 (C5C),
1526 (NO2), 1347 (NO2). 1H NMR (400 MHz, DMSO-d6):
8.56 (s, 1H, NH–CO), 8.38 (t, J = 2.0 Hz, 1H, ArH), 8.20–8.23
(m, 1H, ArH), 7.96 (d, J = 7.6 Hz, 1H, ArH), 7.71 (t, J = 8.0 Hz,
1H, ArH), 7.63 (d, J = 1.6, 7.6 Hz, 1H, ArH), 7.37 (s, 1H, NH),
7.26–7.30 (m, 1H, ArH), 6.80 (d, J = 8.0 Hz, 1H, ArH), 6.69–
6.73 (m, 1H, ArH), 5.97 (s, 1H, CH). 13C NMR (100 MHz.
d
DMSO-d6): d 163.5, 147.7, 147.4, 144.3, 133.7, 133.4, 130.1,
127.5, 123.3, 121.6, 117.6, 115.0, 114.7, 65.2. HRMS (ESI)
for [M+H] found (expected): 269.0796 (269.0800).
3.2. General method for preparing 2-aryl-2,3-
dihydroquinazolin-4(1H)-one derivatives
3.3.4. 2-(2,4-Dimethoxyphenyl)-2,3-dihydroquinazolin-
4(1H)-one C16H16N2O3 (3d)
Co-CNTs (0.008 g) were added to a stirred mixture of 2-
aminobenzamide (1 mmol) and benzaldehyde (1 mmol)
under solventless conditions. After completion of the
reaction, which was monitored by TLC using chloroform:-
methanol (1:3) as the eluent, ice water (15 mL) was added
to it and the resulting precipitate was filtered out, washed
with water, dried under vacuum and purified by recrys-
tallization from ethanol to give the corresponding product.
Yields, melting points, and times of reaction of all the
subsequent compounds are summarized in Table 1.
White solid; Mp 184–186 8C; Rf = 0.35 (petroleum
ether–EtOAc, 1:1); Anal. calcd. for C16H16N2O3 (%) C
67.59, H 5.67, N 9.85. Found C 67.54, H 5.71, N 9.90. IR
(KBr, cmÀ1): 3363 (NH), 3178 (NH), 1670 (C5O), 1639
(C5C), 1253 (C–O), 1048 (C–O). 1H NMR (400 MHz, DMSO-
d6): d 7.95 (s, 1H, NH-CO), 7.62 (d, J = 8.0 Hz, 1H, ArH), 7.32
(d, J = 8.4 Hz, 1H, ArH), 7.20–7.23 (m, 1H, ArH), 6.76 (d,
J = 8.0 Hz, 1H, ArH), 6.72 (s, 1H, NH), 6.66 (t, J = 7.6 Hz, 1H,
ArH), 6.5–6.59 (m, 2H, ArH), 5.95 (s, 1H, CH), 3.81 (s, 3H,
OCH3), 3.75 (s, 3H, OCH3). 13C-NMR (100 MHz, DMSO-d6):
d
164.0, 160.7, 157.5, 148.2, 133.2, 127.8, 127.3, 121.3, 117.0,
114.8, 114.5, 104.5, 98.4, 60.8, 55.6, 55.3. HRMS (ESI) for
[M+H] found (expected): 284.1156 (284.1160).
3.3. Spectral data of the products
3.3.1. 2-Phenyl-2,3-dihydroquinazolin-4(1H)-one
C
14H12N2O (3a)
White solid; Mp 216–218 8C; Rf = 0.4 (petroleum ether–
3.3.5. 2-(4-Methoxyphenyl)-2,3-dihydroquinazolin-4(1H)-
one C15H14N2O2 (3e)
EtOAc, 1:1); Anal. calcd. for C14H12N2O (%) C 74.98, H 5.39,
N 12.49. Found C 74.94, H 5.43, N 12.52. IR (KBr, cmÀ1):
3304 (NH), 3186 (NH), 1654 (C5O), 1613 (C5C). 1H NMR
White solid; Mp 181–183 8C; Rf = 0.35 (petroleum
ether–EtOAc, 1:1); Anal. calcd. for C15H14N2O2 (%) C
70.85, H 5.55, N 11.02. Found C 70.81, H 5.48, N 11.07.
IR (KBr, cmÀ1): 3370 (NH), 3296 (NH), 1650 (C5O), 1608
(C5C), 1240 (C–O), 1037 (C–O). .1H NMR (400 MHz, DMSO-
(400 MHz, DMSO-d6):
d 8.30 (s, 1H, NH–CO), 7.61 (t,
J = 6.8 Hz, 1H, ArH), 7.50 (d, J = 7.2 Hz, 2H, ArH), 7.32–7.41
(m, 3H, ArH), 7.22–7.26 (m, 1H, ArH), 7.12 (s, 1H, NH), 6.75
(d, J = 8.0 Hz, 1H, ArH), 6.67 (t, J = 7.2 Hz, 1H, ArH), 5.75 (s,
d6):
d 8.19 (br s, 1H, NH–CO), 7.61 (d, J = 7.2 Hz, 1H, ArH),
7.42 (d, J = 8.4 Hz, 2H, ArH), 7.24 (t, J = 7.2 Hz, 1H, ArH), 7.01
(br s, 1H, NH), 6.94 (d, J = 7.6 Hz, 2H, ArH), 6.74 (d, J = 8.0 Hz,
1H, ArH), 6.67 (t, J = 7.2 Hz, 1H, ArH), 5.71 (s, 1H, CH), 3.74
1H, CH). 13C-NMR (100 MHz, DMSO-d6):
d 163.6, 147.9,
141.6, 133.3, 128.5, 128.3, 127.4, 126.9, 117.1, 115.0, 114.4,
66.6. HRMS (ESI) for [M+H] found (expected): 224.0945
(224.0949).
(s, 3H, OCH3). 13C NMR (100 MHz, DMSO-d6):
d 163.7,
159.4, 148.0, 133.4, 133.2, 128.2, 127.4, 117.1, 115.0, 114.4,
113.6, 66.3, 55.2. HRMS (ESI) for [M+H] found (expected):
254.1050 (254.1055).
3.3.2. 2-(4-Hydroxylphenyl)-2,3-dihydroquinazolin-4(1H)-
one C14H12N2O2 (3b)
White solid; Mp 279–280 8C; Rf = 0.3 (petroleum ether–
EtOAc, 1:1); Anal. calcd. for C14H12N2O2 (%) C 69.99, H 5.04,
N 11.66. Found C 69.91, H 5.10, N 11.71. IR (KBr, cmÀ1):
3399 (OH), 3337 (NH), 3184 (NH), 1670 (C5O), 1605
3.3.6. 2-(4-Chlorophenyl)-2,3-dihydroquinazolin-4(1H)-one
C
14H11N2OCl (3f)
White solid; Mp 205–206 8C; Rf = 0.4 (petroleum ether–
EtOAc, 1:1); Anal. calcd. for C14H11N2OCl (%) C 65.00, H
4.29, N 10.83. Found C 64.96, H 4.34, N 10.78. IR (KBr,
cmÀ1): 3310 (NH), 3187 (NH), 1660 (C5O), 1611 (C5C),
1184 (C-Cl). 1H NMR (400 MHz, DMSO-d6)
d 8.36 (br s, 1H,
(C5C), 1237 (C–O). 1H NMR (400 MHz, DMSO-d6):
d 9.51 (s,
1H, NH–CO), 8.35 (s, 1H, NH), 7.59–7.61 (m, 3H, ArH), 7.4
(d, J = 7.6 Hz, 2H, ArH), 7.23–7.27 (m, 1H, ArH), 7.15 (s, 1H,
Please cite this article in press as: Safari J, Gandomi-Ravandi S. Environmentally friendly synthesis of 2-aryl-2,3-
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J. Safari, S. Gandomi-Ravandi / C. R. Chimie xxx (2013) xxx–xxx
NH-CO), 7.62 (d, J = 7.6 Hz, 1H, ArH), 7.52 (d, J = 8.0 Hz, 2H,
ArH), 7.46 (d, J = 8.0 Hz, 2H, ArH), 7.25 (t, J = 7.6 Hz, 1H,
ArH), 7.16 (br s, 1H, NH), 6.75 (d, J = 8.0 Hz, 1H, ArH), 6.69
(t, J = 7.6 Hz, 1H, ArH), 5.78 (s, 1H, CH). 13C NMR (100 MHz,
ArH), 8.27 (s, 1H, NH–CO), 7.98 (t, J 8.4 Hz, 2H, ArH), 7.70 (t,
J 6.4 Hz, 2H, ArH), 7.57 (m, 3H), 7.26 (t, J 7.6 Hz, 1H, ArH),
7.08 (s, 1H, NH), 6.74 (dd, J 8.0, 12.8 Hz, 2H, ArH), 6.49 (s,
1H, CH). 13C NMR (100 MHz, DMSO-d6):
d 163.9, 148.3,
DMSO-d6):
d
163.5, 147.7, 140.7, 133.4, 133.0, 128.8, 128.3,
135.1, 133.7, 133.2, 130.4, 129.2, 128.5, 127.4, 126.0, 125.7,
125.1, 124.4, 117.2, 114.9, 114.4, 65.8. HRMS (ESI) for
[M+H] found (expected): 274.1102 (274.1106).
127.4, 117.3, 115.0, 114.5, 65.8. HRMS (ESI) for [M+H]
found (expected): 258.0556 (258.0560).
3.3.7. 2-P-tolyl-2,3-dihydroquinazolin-4(1H)-one
4. Conclusions
C15H14N2O (3g)
White solid; Mp 225–227 8C; Rf = 0.35 (petroleum
Because of the importance of quinazolinone analo-
gues as synthons in organic synthesis, we have reported
the synthesis of a number of these compounds through
the Co-CNT catalyzed heterocyclization of o-aminoben-
zamide with different aldehydes. Mildness, short reac-
tion times, work-up easiness are the superiorities of this
green protocol for the synthesis of 2-aryl-2,3-dihydro-
quinazolin-4(1H)-ones, which can moreover be applied
to large-scale reactions. Also, the synthesis route to
Fe3O4/MWCNT composites is simple and can be carried
out under ambient conditions. This method might be
useful in the future for the preparation of similar
derivatives.
ether–EtOAc, 1:1); Anal. calcd. for C15H14N2O (%)
C
75.61, H 5.92, N 11.76. Found C 75.57, N 5.89, N 11.72.
IR (KBr, cmÀ1): 3310 (NH), 3190 (NH), 1667 (C5O), 1606
(C5C). 1H NMR (400 MHz, DMSO-d6):
d 8.26 (s, 1H, NH–
CO), 7.62 (d, J = 7.6 Hz, 1H, ArH), 7.38 (d, J = 8.0 Hz, 2H,
ArH), 7.17–7.25 (m, 3H, ArH), 7.07 (s, 1H, NH), 6.75 (d,
J = 8.0 Hz, 1H, ArH), 6.66 (t, J = 7.6 Hz, 1H, ArH), 5.72 (s, 1H,
CH), 2.28 (s, 3H, CH3). 13C NMR (100 MHz, DMSO-d6):
d
163.7, 148.0, 138.7, 137.8, 133.3, 128.9, 127.4, 126.9, 117.1,
115.0, 114.5, 66.5, 20.8. HRMS (ESI) for [M+H] found
(expected): 238.1101 (238.1106).
3.3.8. 2-(4-Cyanophenyl)-2,3-dihydroquinazolin-4(1H)-one
C16H10N4O (3h)
Acknowledgment
White solid; Mp 250–252 8C; Rf = 0.4 (petroleum ether–
EtOAc, 1:1); Anal. calcd. for C16H10N4O (%) C 70.07, H 3.67,
N 20.43. Found C 70.02, H 3.62 N 20.39. IR (KBr, cmÀ1):
3336 (NH), 3353 (NH), 2227 (CN), 1666 (C5O), 1611 (C5C).
We are thankful to the University of Kashan Research
Council for partial support of this work (Grant No. 159198/
20).
1H NMR (400 MHz, DMSO-d6):
d 8.46 (s, 1H, NH–CO); 7.86
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6.76 (d, J = 8.05 Hz, 1H, ArH), 6.67 (t, J = 7.45 Hz, 1H, ArH),
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Please cite this article in press as: Safari J, Gandomi-Ravandi S. Environmentally friendly synthesis of 2-aryl-2,3-
dihydroquinazolin-4(1H)-ones by novel Co-CNTs as recoverable catalysts. C. R. Chimie (2013), http://dx.doi.org/
10.1016/j.crci.2013.06.007

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Please cite this article in press as: Safari J, Gandomi-Ravandi S. Environmentally friendly synthesis of 2-aryl-2,3-
dihydroquinazolin-4(1H)-ones by novel Co-CNTs as recoverable catalysts. C. R. Chimie (2013), http://dx.doi.org/
10.1016/j.crci.2013.06.007