Solvent-free syntheses of some quinazolin-4(3H)-ones derivatives

Article abstract of DOI:10.1139/V08-149

Solvent-free syntheses of quinazolin-4(3H)-ones were performed by reaction of anthranillic acid with different amides, such as nicotinamide, benzamide, formamide, etc., on montmorillonite K-10. Products were confirmed by FTIR, ¹HNMR, and ¹³CNMR spectroscopic techniques. All synthesized compounds exhibited antioxidant properties and have been compared with standard antioxidant BHT.

Full text of DOI:10.1139/V08-149

1
019
Solvent-free syntheses of some quinazolin-4(3H)-
ones derivatives
S. Mohana Roopan, T. Maiyalagan, and F. Nawaz Khan
Abstract: Solvent-free syntheses of quinazolin-4(3H)-ones were performed by reaction of anthranillic acid with differ-
ent amides, such as nicotinamide, benzamide, formamide, etc., on montmorillonite K-10. Products were confirmed by
1
13
FTIR, HNMR, and CNMR spectroscopic techniques. All synthesized compounds exhibited antioxidant properties and
have been compared with standard antioxidant BHT.
Key words: quinazolinone, montmorillonite K-10, solvent-free conditions, antioxidant properties.
Résumé : On a réalisé des synthèses sans solvant de quinazolin-4(3H)-ones par réaction de l’acide anthranillique avec
divers amides, tel le nicotinamide, le benzamide et le formamide sur de la montmorillonite K-10. Les produits ont été
caractérisés par la spectroscopie infrarouge avec transformée de Fourier (IR-TF), et par les méthodes spectroscopiques
1
13
de RMN du H et du C. Tous les produits synthétisés présentent une propriété antioxydante et ils ont été comparés
avec l’antioxydant standard, BHT.
Mots-clés : quinazolinone, montmorrillonite K-10, conditions sans solvant, propriétés antioxydante
[
Traduit par la Rédaction] Roopan et al. 1025
Introduction
tally and industrially important organic syntheses that are
more effective and eco-friendly than conventional reactions
The quinazoline ring skeleton is widely found in alkaloids
and many biologically active compounds. In general, quina-
zolones were considered important compounds in the fields
of pharmacology and biology (1) because of their wide range
of strong biological activities (2–6). Some of these com-
pounds are identified as drugs (7) and as diuretics. Among
this class of molecules, quinazolin-4-ones and their deriva-
tives are well-known to possess an array of physiological
activities, e.g., antitubercular (8), antifungal (9), antibacterial
(
19, 20).
In continuation of our interest in C–C bond-forming reac-
tions (21–25), we have explored a one-pot synthesis of
quinazolin-4(3H)-ones (Schemes 1 and 2, Tables 1 and 2)
from anthranillic acid and amides, such as formamide,
acetamide, benzamide, nicotinamide, etc., in the presence of
montmorillonite K-10 catalyst and other inorganic catalysts
such as acidic alumina, bentonite, etc., (Table 3), under
solvent-free conditions. The above reactions, carried out
over montmorillonite K-10 clay, give good yields because of
the ditopic nature (26, 27) of montmorillonite K-10 clay.
However, the reaction takes less time to complete. The opti-
mization of catalyst amount was also done (Table 4). Thus,
we have developed a simple, economical, and environmen-
tally benign synthesis of classical procedures, by avoiding
volatile and toxic organic solvents. The reusability of the
catalyst in synthesis has also been explored (Table 5). Scope
of the reaction (Tables 1 and 2) and antioxidant properties of
the reaction products have also been discussed.
(
(
10), anti-inflammatory, anticancer (11), and anti-proliferative
5) activities.
Quinazolin-4(3H)-one was prepared by many methods (5,
, 10–13). However, quinazoline derivatives were synthe-
8
sized mainly by a common approach involving amidation,
starting from anthranilic acid, 2-aminobenzonitrile, and 2-
aminobenzamide. Other methods included the condensation
of anthranilic acid, ammonium acetate, and the orthoesters
(
14), reaction of imidates and anthranilic acid (15), reaction
of polymer-bound isothioureas with isatoic anhydride deriv-
atives (16), and were associated with drawbacks such as
multistep procedures (17), costly reagents, harse reaction
conditions, complex experimental procedures, and low
yields (18). Previous methods have been excluded from
practical applications because of environmental and eco-
nomic considerations. Finding an efficient method for the
synthesis of quinazolin-4(3H)-one is still a challenge. Nowa-
days, solvent-free organic reactions have led to experimen-
Experimental
Anthranillic acid and amides used for the reaction were
from Sigma-Aldrich Co., and montmorillonite K-10 was ob-
tained from Fluka. The substances were used as provided
with no other purification. Melting points were taken in
open capillary tubes and are corrected with reference to ben-
Received 17 March 2008. Accepted 29 August 2008. Published on the NRC Research Press Web site at canjchem.nrc.ca on
October 2008.
8
1
1
S.M. Roopan, T. Maiyalagan, and F.N. Khan. School of Science and Humanities, Organic Chemistry Division, VIT University,
Vellore 632 014, Tamil Nadu, India.
1Corresponding authors (e-mail: maiyalagan@gmail.com, nawaz_f@yahoo.co.in).
Can. J. Chem. 86: 1019–1025 (2008)
doi:10.1139/V08-149
© 2008 NRC Canada

1
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Can. J. Chem. Vol. 86, 2008
Table 1. Synthesis of 2-substituted quinazolinone by solvent-free montmorillonite K-10 catalysis.
Scheme 1. Montmorillonite K-10 catalysed reaction of
Scheme 2. Montmorillonite K-10 catalysed reaction of
anthranillic acid and different amides.
anthranillic acid with urea and thiourea.
zoic acid. IR spectra in KBr pellets were recorded on Nucon
infrared spectrophotometer. Nuclear Magnetic Resonance
General procedure for the synthesis of 2-substituted-
3H-quinazolin-4-ones and 1H,3H-quinazolin-2,4-diones
A mixture of anthranillic acid, 1 amide, 2 or 4a or 4b, and
montmorillonite K-10 clay when heated under reflux
conditions gave 2-substituted-3H-quinazolin-4-one 3 or
1H,3H-quinazolin-2,4-dione 5 (Scheme 1). After completion
1
13
(
H and C) spectra were recorded on a Bruker Spectrospin
Avance DPX400 Ultrashield (400 MHz) spectrometer.
Chemical shifts are reported in parts per million (δ)
downfield from an internal tetramethylsilane reference.
©
2008 NRC Canada

Roopan et al.
1021
Table 1 (concluded).
Note: 1 = 10 mmol, 2 = 10 mmol, catalyst = 0.1 g.
a
3
in isolated yields after column chromatography.
b
1
All products were characterized by H NMR and IR spectroscopic data and their melting points were compared with
literature values (31–32).
of the reaction, ethyl acetate was added to the reaction mix-
ture, and the catalyst was recovered by filtration. Filtrate
Synthesis of 2-pyridin-3-yl-3H-quinazolin-4-one (3a)
Anthranillic acid (10 mmol), nicotinamide 2a
(10 mmol), and montmorillonite K-10 (0.1 g) were placed in
a mortar and mixed well, transferred to a 50 mL round-
bottomed flask, and refluxed at 150 °C for 30 min. The reac-
tion was monitored by TLC, and after completion of the re-
action, work-up was performed as above to give crude
1
was washed with a 10% NaHCO solution to remove any
3
unreacted acid and further washed with water to remove any
inorganic materials. The organic layer was dried, solvent
evaporated to obtain the products. FT-IR and NMR spectral
techniques were used for product analysis.
©
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1
022
Can. J. Chem. Vol. 86, 2008
Table 2. Synthesis of quinazolidione by solvent-free montmorillonite K-10 catalysis.
Note: 1 = 10 mmol, 4 = 10 mmol, catalyst = 0.1g.
a
5
in isolated yields.
Table 3. Selection of catalyst.
Refluxing at 150 °C solvent-free conditions
Sl. No.
Catalyst used
Catalyst amount (mg)
Time (h)
Product 3a
1
2
3
4
5
Silica gel
Bentonite
Montmorillonite KSF
Acidic alumina
Montmorillonite K10
10
10
10
10
10
4
4
4
4
Nil
Nil
Nil
Low yield
High yield
0.5
Note: Anthranilic acid 1 (1 mmol) and nicotinamide 2a (1 mmol).
Table 4. Optimization of catalyst concentration.
Refluxing at 150 °C solvent-free conditions
Amide, R
RCONH2
Montmorillonite
K-10 (g)
Time
(h)
Product 3a
(R)
Yielda
(%)
Sl. No.
1
2
3
4
5
6
7
8
-C H N
None
0.02
0.04
0.06
0.08
0.1
2
-C H N
40
59
67
65
71
85
86
86
5
4
5
4
-C H N
1
-C H N
5 4
5
4
-C H N
1
-C H N
5 4
5
4
-C H N
1
-C H N
5 4
5
4
-C H N
0.5
0.5
0.5
0.5
-C H N
5 4
5
4
-C H N
-C H N
5 4
5
4
-C H N
0.12
0.14
-C H N
5 4
5
4
-C H N
-C H N
5 4
5
4
Note: 1 = 10 mmol, 2a = 10mmol, refluxed at 150 °C.
a
3a in isolated yields.
©
2008 NRC Canada

Roopan et al.
1023
Fig. 1. Time vs. absorbance graph for antioxidant property of
Table 5. Life cycle of catalyst.
quinazolinone derivatives.
Catalyst
amount (g)
Yield
(%)
Entry
Cycle No.
1
2
3
Cycle I
Cycle II
Cycle III
0.1
0.096
0.091
85
82
81
product. Pure 2-pyridin-3-yl-3H-quinazolin-4-one 3a was
obtained by performing column chromatography using silica
gel and petroleum ether/ethyl acetate as eluent. Yield was
determined (Table 1, compound 3a). The quinazolinone 3a
was recrystallized from petroleum ether and ethyl acetate.
The melting point was found to be 114 °C.
A similar procedure was followed to obtain other
quinazolinone derivatives 3 from different amides 2
(
Scheme 1 and Table 1). Products were characterized by
1
13
FTIR, HNMR, CNMR, and GCMS spectral techniques,
and known compounds were compared with literature re-
ports. The recrystallization of products was effected using
petroleum ether and ethyl acetate.
tems. In this study, the free-radical scavenging activity of
quinazolin-4(3H)-ones derivative was measured by a 1,1-
diphenyl-2-picryl-hydrazyl (DPPH) method. This activity
was measured by the following Blos methodology as as-
sessed by Ansari et al. (28). The absorbance of DPPH is
monitored at a characteristic wavelength in the presence of a
synthesized sample. In its radical form, DPPH absorbs at
Synthesis of 1H,3H-quinazolin-2,4-dione (5a)
A mixture of anthranillic acid 1 (10 mmol), urea 4a
(
10 mmol), and 0.1 g of montmorillonite K-10 was heated
under reflux conditions (150 °C) for 2 h. After completion
of the reaction, the catalyst was removed by filtration; the
mixture was poured into ice-cooled water and extracted with
ethyl acetate. The product 5a, obtained after solvent re-
moval, was purified by performing column chromatography
using silica gel and petroleum ether/ethyl acetate as eluent
5
17 nm, but upon reduction by an antioxidant or a radical
–
4
species its absorption decreases. Briefly, a 1.5 × 10
mmol/L solution of DPPH in ethanol was prepared and 1
mL of this solution was added to 3 mL of 1.5 × 10–4 mmol/L
of quinazolinone in ethanol. At each 5 min interval,
absorbance was measured at 517 nm until 30 min. The stan–-
dard used was butylated hydroxyl toluene (BHT), (1.5 × 10
(
Scheme 2, Table 2). The quinazolindione 5a was
recrystallized from petroleum ether and ethyl acetate. The
melting point was found to be >300 °C.
Synthesis of 2-thioxo-2,3-dihydro-1H-quinazolin-4-one
4
mmol/L) in ethanol solution. Lower absorbance of reaction
(
5b)
A mixture of anthranillic acid 1 (10 mmol), thiourea 4b
10 mmol), and 0.1 g of montmorillonite K-10 was heated
mixture indicates higher free-radical scavenging activity.
Absorbance of the DPPH (control) is 1.544. The capability
to scavenge DPPH radical (28, 29) was calculated using the
following equation,
(
under reflux conditions (150 °C) for 2 h. After completion
of the reaction, the catalyst was removed; the mixture was
poured into ice-cooled water and extracted with ethyl ace-
tate. The product 5b, obtained after solvent removal, was pu-
rified by column chromatography (Scheme 2, Table 2). The
dihydroquinazolinone 5b was recrystallized from ethyl ace-
tate. The melting point was found to be >300 °C.
DPPH Scavenging effect (%)
=
[(Acontrol – Asample / Acontrol) * 100]
where Acontrol is the absorbance of the DPPH solution and
Asample is the absorbance in the presence of quinazolinone.
Two different graphs (Figs. 1 and 2) are plotted with time
vs. absorbance and time vs. % inhibition.
Life cycle of the catalyst
The reusability of catalyst was explored by checking the
successive runs of the reactions on recycled catalyst; i.e., af-
ter first run of the reaction, the catalyst was recovered by a
simple filtration from reaction mixture, washed with ethyl
acetate, and dried. Then it was utilized in the second run of
the reaction. It was noticed that use of recycled catalyst in
subsequent experiments gave similar yields (Table 5). Thus,
the catalyst is not leached.
Results and discussion
Solvent-free syntheses of quinazolinone 3a from
anthranillic acid 1 and nicotinamide 2a have been explored
by using inorganic catalysts such as montmorillonite K-10,
silica gel, acidic alumina, etc. (Table 3). Preliminary results
indicated the formation of quinazolinone in high yield only
in the case of montmorillonite K-10. The optimization of
catalyst amount was done to improve the yield (Table 4).
Montmorillonite K-10 has had a great impact in organic syn-
thesis and has offered major breakthroughs for the manufac-
ture of fine chemicals. This reagent has advantages over the
Free-radical scavenging activity of quinazolinone
derivatives
Radical scavenging activities are very important due to the
deleterious role of free radicals in foods and biological sys-
©
2008 NRC Canada

1
024
Can. J. Chem. Vol. 86, 2008
Fig. 2. Time vs. % inhibition graph for antioxidant property of
quinazolinone derivatives.
compared with commercial antioxidant butylated hydroxyl
toluene (BHT). 2-Thioxo-2,3-dihydro-1H-quinazolin-4-one
had relatively high DPPH radical-scavenging activity. As
shown in Figs. 1 and 2, all quinazolinone derivatives were
found to have the ability to scavenge hydroxyl radical at a
–
4
concentration of 1.5 × 10 mmol/L.
Analytical data
Data of the new compound 3a and that of a few known
compounds, 3b–3d, 5a–5b, which have not been reported
earlier are given below. The data of a few compounds that
have been found to be identical to those reported (30–32) are
given as Supplementary Data available with this paper.2
2
-Pyridin-3-yl-3H-quinazolin-4-one (3a)
Colourless solid, mp 114 °C. IR (KBr pellets, cm ) ν:
351.67, 1655.03, 1601.16, 1585.32, 1535.27, 1491.45. H
–
1
1
3
NMR (300MHz, CDCl ) δ: 9.1 (s, 1H), 8.76–8.75 (d, J =
3
4
7
7
.56Hz, 1H), 8.23–8.20 (d, J = 7.77Hz, 1H), 8.13 (s, 1H),
.66–7.64 (d, 1H), 7.46–7.41 (m, 1H), 7.39–7.36 (d, J =
.56, 2H), 7.21–7.16 (m, 1H). C NMR (100 MHz, CDCl3)
1
3
δ: 163.92 (C=O), 152.37, 147.82, 137.49, 135.49, 130.86,
conventional homogeneous solution techniques: easy set-up
and work-up, mild experimental conditions, and high yield.
As part of our research, quinazolin-4(3H)-ones were synthe-
sized using K-10 as catalyst (Schemes 1 and 2). The results
of the quinazolinones synthesis are summarized (Tables 1–
1
2
4
7
29.17, 125.08, 123.73, 120.51. EI-Mass: 223. GC-MS m/z
+
23 (M ) C H N O (mol. wt. 223.23) calcd.: C 69.95, H
1
3
9
3
.06, N 18.82, O 7.17; found: C 69.83, H 4.14, N 18.75, O
.01.
5
). The essence of the catalyst can be understood from the
2
-Phenyl-3H-quinazolin-4-one (3b)
following facts: when anthranillic acid 1 was treated with
montmorillonite K-10 under conventional heating in the
presence of nicotinamide 2a, the product 3a was obtained in
quantitative yield (Table 3, entry 5). When the same reaction
was performed without montmorillonite catalyst, 3a was
obtained in much lower yield in 2 h (Table 4, entry 1). The
reaction optimization with different amounts of montmoril-
lonite K-10 was carried out, and at 0.1 g, the yield was good
Mp 242–246 °C (lit. value (32), 242–246 °C). IR (KBr
–1
13
pellets, cm ) ν: 3342.55, 1654.76, 1437.47. C NMR
(
1
100MHz, CDCl ) δ: 165.70 (C=O), 137.85, 134.93, 131.78,
3
29.03, 128.72, 126.95, 124.51, 120.14. C H N O (mol.
14 10 2
wt. 222.24) calcd.: C 75.66, H 4.54, N 12.60, O 7.20; found:
C 75.54, H 4.46, N 12.52, O 7.11.
2
-Methyl-3H-quinazolin-4-one (3c)
(
Table 4).
Mp 240–248 °C (lit. value (32), 238–240 °C). IR (KBr
In the IR spectra of all 4-quinazolinones 3, absorption
–1
pellets, cm ) ν: 3295.81, 1666.07, 1434.67. C H N O (mol.
wt. 160.17) calcd.: C 67.49, H 5.03, N 17.49, O 9.99; found:
C 67.31, H 5.13, N 17.51.
9
8
2
bands are observed in the region of 1690–1730 (Ar C=O),
1
–
1
600–1635, 1510–1570, 1460–1500 cm (the quinazolone
1
ring). Assignments of H NMR signals of quinazolinones 3
were derived from splitting patterns and characteristic chem-
ical shift values. The data consistently show that the
homocyclic proton signal with the lowest field shift in series
of compounds is a doublet with additional fine structure due
to further meta and para couplings. This signal is assigned
to H-5 on the basis of the proximity to the carbonyl group.
The assignment of H-5 led to the assignment of H-8 by de-
fault. In the same spectral region, the signal for H-2 is found
as a singlet. The signals for protons H-6 and H-7 show two
ortho couplings. We have assigned the H-7 signal to the
lower field.
3
H-Quinazolin-4-one (3d)
White solid, mp 216 °C (lit. value (32), 215–216 °C). IR
–1
13
(
(
KBr pellets, cm ) ν: 3428.88, 1704.98, 1665.87. C NMR
75MHz, CDCl ) δ: 143.34, 134.89, 127.76, 127.42, 126.35.
3
C H N O (mol. wt. 146.15) calcd.: C 65.75, H 4.14, N
8
6
2
1
9.17, O 10.95; found: C 65.80, H 4.03, N 19.04, O 10.86.
(4-Oxo-quinazolin-2yl)-acetonitrile (3e)
Colourless solid, mp 240 °C (lit. value (32), 242 °C.
C H N O (mol. wt. 185.18) calcd.: C 64.86, H 3.81, N
1
0
7
3
22.69, O 8.64; found: C 64.74, H 3.91, N 22.57, O, 8.58.
In the present study, quinazolinone derivatives were evalu-
ated for their free-radical scavenging activity using the
DPPH radical assay. Reduction of DPPH radicals can be ob-
served by a decrease in absorbance at 517 nm. Different de-
rivatives of quinazolinones reduced DPPH radicals
significantly. The activity of quinazolinone derivatives was
2-(4-Methylphenyl)quinazolin-4(3H)-one (3g)
Colourless solid, mp 240 °C (lit. value (31), 239 °C). 13C
NMR (75MHz, CDCl ) δ: 159.9, 147.34, 146.20, 134.31,
3
133.20, 131.58, 128.15, 127.12, 126.35, 125.14, 124.81,
+
124.13, 122.11, 19.30. GC-MS m/z 236 (M ).
2
Supplementary data for this article are available on the journal Web site (canjchem.nrc.ca) or may be purchased from the Depository of
Unpublished Data, Document Delivery, CISTI, National Research Council Canada, Ottawa, ON K1A 0R6, Canada. DUD 3833. For more
information on obtaining material refer to cisti-icist.nrc-cnrc.gc.ca/cms/unpub_e.shtml.
©
2008 NRC Canada

Roopan et al.
1025
2
-(4-Methoxyphenyl)quinazolin-4(3H)-one (3h)
5. S. Yang, Z. Li, L. Jin, B. Song, G. Liu, J. Chen, Z. Chen, D.
Pale yellow, mp 245–247 °C (lit. value (31), 244 °C). 13C
Hu, W. Xue, and R. Xu. Bioorg. Med. Chem. Lett. 17, 2193
(
2007).
NMR (75MHz, CDCl ) δ: 161.22, 148.33, 146.20, 134.32,
1
1
3
6
7
. J. Bartroli, E. Turmo, M. Alguero, E. Boncompte, M.L.
Vericat, L.Conte, J. Ramis, M. Merlos, J.G. Rafanell, and J.
Forn. J.Med.Chem. 41, 1869 (1998).
. B.A. Keay and P.W. Dibble. In Comprehensive Heterocyclic
Chemistry. Vol. II. Edited by A.R. Katritzky, C.W. Rees, and
E.F.V. Scriven. Pergamon Press, Oxford, UK. 1996. pp. 395–
436.
33.20, 131.56, 128.11, 127.10, 126.22, 125.14, 124.81,
+
24.21, 122.13, 19.31. GC-MS m/z 252 (M ).
2
-(4-Chlorophenyl)quinazolin-4(3H)-one (3j)
Colourless solid, mp 306–308 °C (lit. value (31), 312 °C).
1
3
C NMR (75MHz, CDCl ) δ: 160.12, 147.73, 146.64,
3
1
1
36.45, 135.26, 134.66, 132.62, 130.55, 128.33, 127.91,
8
9
. J. Kunes, J. Bazant, M. Pour, K. Waisser, M. Slosarek, and J.
Janota. Il Farmaco, 55, 725 (2000).
. G. Grover and S.G. Kini. Eur. J. Med. Chem. 41, 256 (2006).
+
26.84, 124.14, 122.43, 19.31. GC-MS m/z 240 (M ).
1
H,3H-Quinazolin-2,4-dione (5a)
10. A.K. Tiwari, V.K. Singh, A. Bajpai, G. Shukla, S. Singh, and
Pale yellow solid, mp >300 °C (lit. value (32) >280 °C).
A.K. Mishra. Eur. J. Med. Chem. 42, 1234 (2007).
11. P.M. Chandrika, T. Yakaiah, A.R.R. Rao, B. Narsaiah, N.C.
Reddy, V. Sridhar, and J.V. Rao. Eur. J. Med. Chem. 43, 846
–
1
IR (KBr pellets, cm ) ν: 3367.88 (br), 1673.92, 1609.99.
C H N O (mol. wt. 162.15) calcd.: C 59.26, H 3.73, N
8
6
2
2
(
2008).
1
2
3
7.28, O 19.73; found: C 59.14, H 3.67, N 17.16, O 19.82.
1
2. D.J. Connolly, D.Cusack, T.P.O. Sullivan, and P.J. Guiry. Tet-
rahedron, 61, 10153 (2005).
-Thioxo-2,3-dihydro-1H-quinazolin-4-one (5b)
Colourless solid, mp >300 °C. IR (KBr pellets, cm ) ν:
406.32, 3203.67, 3008.42, 1696.52, 1263.87. H NMR
–
1
13. G.M. Buckley, N. Davies, H.J. Dyke, P.J. Gilbert, D.R.
Hannah, A.F. Haughan, C.A. Hunt, W.R. Pitt, R.H. Profit, N.C.
Ray, M.D. Richard, A. Sharpe, A.J. Taylor, J.M. Whitworth,
and S.C. Williams. Bioorg. Med. Chem. Lett. 15, 751 (2005).
4. K. Rad-Moghadam and M. Mohseni. J. Chem. Res.
Synop. 487 (2003).
15. W. Ried and W. Stephan. Chem. Ber. 96, 1218 (1963).
6. R.Y. Yang and A. Kaplan. Tetrahedron Lett. 41, 7005 (2000).
7. V. Alagarsamy, S. Murugesan, K. Dhanabal, M. Murugan, and
E. De Clercq. Indian J. Pharm. Sci. 69, 304 (2007).
8. P. Pannerselvam, R.V. Pradeepchandran, and S.K. Sridhar. In-
dian J. Pharm. Sci. 65, 268 (2003).
1
(
7
400MHz, CDCl ) δ: 7.89 (s, 1H, NH), 7.45–7.44 (d, 1H),
3
1
3
.43–7.42 (d, 1H), 7.41–7.37(m, 2H) 7.34 (s, 1H, NH).
C
1
NMR (100MHz, CDCl ) δ: 179.94 (C=S), 137.05, 129.62,
27.15, 125.30. C H N OS (mol. wt. 178.21) calcd.: C
3
1
5
3
8 6 2
3.92, H 3.39, N 15.72, O 8.98, S 17.99; found: C 53.84, H
.48, N 15.81, O 8.87, S 17.87.
1
1
1
Conclusion
1
2
2
9. R.S. Varma. Green Chem. 1, 43 (1999).
In conclusion, we have reported a facile synthesis of
quinazolin-4(3H)-ones under solvent-free conditions and
conventional heating, demonstrating the use of montmorillo-
nite K-10 as an efficient, rapid, mild, and inexpensive cata-
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Acknowledgement
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The authors wish to express their gratitude to Syngene
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2008 NRC Canada