One-pot synthesis of 2,3-dihydro-2-thioxoquinazolin-4(1H)-ones from nitro-compounds with the aid of tin(II) chloride

Article abstract of DOI:10.1002/jhet.392

(Chemical Equation Presented) A facile synthetic method using SnCl ₂·2H₂O system to promote the novel reductive cyclization of 2-nitrobenzamides and isothiocyanates is described. Sequentially, a series of 2,3-dihydro-2-thioxoquinazolin-4(1H)-ones were synthesized in good yields.

Full text of DOI:10.1002/jhet.392

July 2010
One-Pot Synthesis of 2,3-Dihydro-2-thioxoquinazolin-4(1H)-ones
from Nitro-Compounds with the Aid of Tin(II) Chloride
939
Man-Man Wang, Guo-Lan Dou, and Da-Qing Shi*
Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical and
Materials Science, Soochow University, Suzhou 215123, People’s Republic of China
*E-mail: dqshi@suda.edu.cn
Received October 17, 2009
DOI 10.1002/jhet.392
Published online 18 June 2010 in Wiley InterScience (www.interscience.wiley.com).
A facile synthetic method using SnCl2ꢀ2H2O system to promote the novel reductive cyclization of 2-
nitrobenzamides and isothiocyanates is described. Sequentially, a series of 2,3-dihydro-2-thioxoquinazo-
lin-4(1H)-ones were synthesized in good yields.
J. Heterocyclic Chem., 47, 939 (2010).
INTRODUCTION
aldehydes and ketones [22]. Our group also have
reported the synthesis of quinazolinones [23], quinazo-
line-2,4-diones [24], imidazo[1,2-c]quinazolinones [24],
and 2-thioxo- quinazolinones [25,26] by the reaction of
nitro-compounds with orthoformates, triphosgene,
ketones, and isothiocyanates, respectively, induced by
low-valent titanium reagent. However, these methods
suffer from some disadvantages such as drastic condi-
tions, unsatisfactory yields, long-reaction time, higher
temperature, complex manipulation, and inaccessible
starting materials. Therefore, the development of more
efficient methods for preparing this kind of compounds
with milder reaction conditions is highly desired.
It has been reported that quinazolineones are responsi-
ble for a variety of biological responses, including appli-
cations for hypertension [1], diabetes [2], cancer [3],
inflammation [4], and immunosuppression [4]. The qui-
nazolindione moiety, in particular, is widely found in
natural purine bases [5], alkaloids, intermediates in or-
ganic synthesis [6], and many biologically active com-
pounds. For example, 6,7-dimethoxy-1H-quinazoline-
2,4-dione is a key intermediate for the production of the
following medicines (Prazosin (Minipress) [7], Bunazo-
sin (Detantol) [8], and Doxazosin (Cardenalin [9]). 7-
Chloro-1H-quinazoline-2,4-diones is also a key interme-
diate for the production of the medicines such as FK366
[10] and KF31327 [11].
In recent years, our interest has been focused on the
usage of SnCl2 reagent. We have previously reported
the synthesis of 2-aryl-2H-indazoles [27], 1-hydroxy
quinazolinones [28], imidazo[1,2-c]quinazoline-5(6H)-
thione, and imidazo[1,2-c]quinazolin-5(6H)-one [29],
respectively, mediated by SnCl2 reagent. As our earlier
works goes, herein, we will describe a new approach to
synthesizing 2,3-dihydro-2-thioxoquinazolin-4(1H)-ones
by treating 2-nitrobenzamides with isothiocyanates
mediated by SnCl2 reagent.
The conventional syntheses of quinazolinedione ring
system are carried out by anthranilic acid with urea
[12a,b], anthranilamide with phosgene [13], and anthra-
nilic acid with potassium cyanate [14] or chlorosulfonyl
isocyanate [15]. Recently, several methods have been
developed for synthesizing this heterocyclic system, for
example, Mizuno and Iahino have reported the simple
solvent-free synthesis of 1H-quinazoline-2,4-diones
using supercritical carbon dioxide and catalytic amount
of base [16]. Buckman and Mohan have reported the
solid-phase synthesis of quinazoline-2,4-diones [17–20].
Li et al. reported the synthesis of 2,4(1H,3H)-quinazoli-
nediones and 2-thioxoquinazolines [21]. Alagarsamy et
al. reported the synthesis of 3-phenyl-2-substituted-3H-
quinazolin-4-ones by reaction of the amino group of 2-
hydrazino-3-phenyl-3H-quinazolin-4-one with different
RESULTS AND DISCUSSION
On the basis of our previous experience, we selected
2-nitrobenzamide 1a and the 3-methylphenyl isothiocya-
nate 2a as model substrates to optimize the experimental
conditions for the proposed reductive cyclization reac-
tion (Scheme 1). The results are summarized in Table 1.
C
V
2010 HeteroCorporation

940
M.-M. Wang, G.-L. Dou, and D.-Q. Shi
Vol 47
Scheme 1
Scheme 2
As shown in Table 1, we firstly examined the effect
of different reductive systems (entries 1–4), and con-
cluded that SnCl2ꢀ2H2O was the best. Then, we also
briefly examined the effect of different temperatures,
different solvents, and ratio of 1a:SnCl2ꢀ2H2O. The
results showed that at refluxing temperature the reaction
preceded smoothly in high yield. To further evaluate the
influence of the ratio of 1a:SnCl2ꢀ2H2O, the reaction
was carried out in acetonitrile using a 1:1 to 1:5 ratio of
1a:SnCl2ꢀ2H2O (Table 1, entries 8, 9, 10, 1, 11), leading
to 3a in 26%, 33%, 60%, 75%, and 72% yields, respec-
tively. We concluded the best ratio of 1a:SnCl2ꢀ2H2O
was 1:4. Moreover, different organic solvents were fur-
ther investigated as shown in Table 1; we concluded
that acetonitrile was the best solvent for this reaction.
With the optimized conditions in hand, we then per-
formed the reaction of a variety of 2-nitrobenzamides 1
and isothiocyanates 2 via tin(II) chloride systerm
(Scheme 2, Table 2).
thermore, it was particularly noteworthy that the effects
of substituted o-nitrobenzamides were also investigated.
3-Methyl and 4-chloro substitution can also give moder-
ate to good yields.
Moreover, we also studied the reaction of a variety of
N-substitued-o-nitrobenzamides 4 and isothiocyanates 2
under optimized conditions. The desired products 3
were obtained in good yields (Scheme 3, Table 3).
Similarly, N-substitued-o-nitrobenzamides containing
electron-donating and electron-withdrawing substituents
were reacted well with aryl isothiocyanates and aliphatic
isothiocyanates; therefore, we can conclude that the
electronic nature of the substituents has no significant
effect on this reaction. Meanwhile, it was found that
o-nitrobenzamides showed better reactivity trends than
N-substituted-o-nitrobenzamides.
A plausible mechanistic pathway to products 3 is
illustrated in Scheme 4, although the details are still
unclear. In the initial step, 1 or 4 are reduced by tin (II)
chloride to A. The amine compounds A then reacted
with isothiocyanates to give intermediate B. Intermedi-
ate C was formed by attack of the amino group onto the
the central carbon atom of the carbonyl. Finally, prod-
ucts 3 were obtained by eliminating of an amine
molecule.
As shown in Table 2, it can be seen that this protocol
can be applied not only to the aryl isothiocyanates with
electron-withdrawing groups (such as halide groups) or
electron-donating groups (such as alkyl groups) but also
to aliphatic isothiocyanates under the same conditions,
which highlighted the wide scope of this reaction. Fur-
For the investigation of the reaction mechanism, the
intermediate of 3j (2-amino-N-(4-methoxy- phenyl)ben-
zamide) was isolated and characterized by spectroscopic
methods. When the intermediate and 1-isothiocyanato-4-
Table 1
Optimization for the reductive cyclization reaction.
Reductive Temperature
(ꢁC)
Yield
(%)
Entry
system
Ratioa
Solvent
1
SnCl2ꢀ2H2O
Fe/HCl
Zn/HOAc
reflux
reflux
reflux
reflux
r.t
1:4
1:4
1:4
1:4
1:4
1:4
1:4
1:1
1:2
1:3
1:5
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
75
47
38
0
Table 2
2
3
Synthesis of compounds 3 from o-nitrobenzamides 1 and
isothiocyanates 2.
4
5
Mg/HCl
SnCl2ꢀ2H2O
SnCl2ꢀ2H2O
SnCl2ꢀ2H2O
SnCl2ꢀ2H2O
SnCl2ꢀ2H2O
SnCl2ꢀ2H2O
SnCl2ꢀ2H2O
SnCl2ꢀ2H2O
SnCl2ꢀ2H2O
SnCl2ꢀ2H2O
0
X
Y
Z
R
Yield (%)
6
40
60
20
45
26
33
60
72
0
7
8
3a
3b
3c
3d
3e
3f
3g
3h
3i
H
H
H
H
H
H
Cl
Cl
H
H
H
H
H
3-CH3C6H4
C6H5CH2
n-Butyl
4-ClC6H4
n-Butyl
75
83
91
81
91
76
87
83
80
reflux
reflux
reflux
reflux
reflux
reflux
reflux
9
H
CH3
H
H
H
10
11
12
13
14
H
H
1:4 CH3CH2OH
H
4-ClC6H4
C6H5
1:4
1:4
CHCl3
DMF
56
30
H
Cl
Cl
Cl
H
H
3-CH3C6H4
n-Butyl
a Ratio of 1 and reductive agent.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

July 2010
One-Pot Synthesis of 2,3-Dihydro-2-thioxoquinazolin-4(1H)-ones from
Nitro-Compounds with the Aid of Tin(II) Chloride
941
Scheme 3
Scheme 4
methylbenzene 2j were reacted under the same reaction
conditions, the product 3j was obtained in 82% yield.
The structures of products 3 were confirmed by IR
1
and H NMR.
In summary, a series of 2,3-dihydro-2-thioxo-quinazo-
lin-4(1H)-ones were synthesized via SnCl2ꢀ2H2O
induced reductive cyclization of isothiocyanates with 2-
nitrobenzamides. A variety of substrates can participate
in the process with good yields. The new method has
advantages such as easily accessible starting materials,
handy manipulation (only one pot), moderate to high
yields, and isolation of products via simple recrystalliza-
tion to give higher purities.
21; 286–288ꢁC); IR (KBr) m: 3248, 3134, 3028, 1664, 1621,
1529, 1488, 1402, 1340, 1271, 1203, 913, 798, 692,
1
651 cmꢂ1. H NMR (DMSO-d6): 2.34 (s, 3H, CH3), 7.07 (d,
J ¼ 8.8 Hz, 2H, ArH), 7.22 (d, J ¼ 7.6 Hz, 1H, ArH), 7.33–
7.38 (m, 2H, ArH), 7.45 (d, J ¼ 8.4 Hz, 1H, ArH), 7.78 (t,
J ¼ 7.2 Hz, 1H, ArH), 7.95 (d, J ¼ 8.0 Hz, 1H, ArH), 13.02
(s, 1H, NH).
3-Benzyl-2-thioxo-2,3-dihydroquinazolin-4(1H)-one (3b). This
compound was obtained as solid with mp 238–240ꢁC (ref. 25;
235–236ꢁC); IR (KBr) m: 3201, 3129, 3073, 1688, 1623, 1542,
1489, 1436, 1340, 1291, 1181, 959, 760, 705, 686 cmꢂ1 1H
.
NMR (DMSO-d6): 5.67 (s, 2H, CH2), 7.21–7.24 (m, 1H, ArH),
7.27–7.37 (m, 5H, ArH), 7.43 (d, J ¼ 8.0 Hz, 1H, ArH), 7.77
(t, J ¼ 7.2 Hz, 1H, ArH), 7.96 (d, J ¼ 8.0 Hz, 1H, ArH),
13.07 (s, 1H, NH).
EXPERIMENTAL
Commercial solvents and reagents were used as received.
Melting points are uncorrected. IR spectra were recorded on
Varian F-1000 spectrometer in KBr with absorptions in cmꢂ1
1H NMR was determined on Varian-400 MHz spectrometer in
DMSO-d6 or CDCl3-d6 solution. J values are in Hz. Chemical
shifts are expressed in ppm downfield from internal standard
TMS.
General procedure for synthesis of 2,3-dihydro-2-thioxo-
quinazolin-4(1H)-ones 3. A solution of 1 or 4 (1 mmol), iso-
thiocyanates 2 (1 mmol), and SnCl2ꢀ2H2O (4 mmol) in
CH3CN (5 mL) was stirred at reflux for 2–3 h. After this pe-
riod, the TLC analysis of the mixture showed the reaction to
be completed. The mixture was quenched with 3% HCl (10
mL) and filtered, and the crude product was purified by recrys-
tallization from 95% ethanol and DMF.
3-Butyl-2-thioxo-2,3-dihydroquinazolin-4(1H)-one (3c). This
compound was obtained as solid with mp 164–166ꢁC (ref. 25;
166–167ꢁC); IR (KBr) m: 3250, 3144, 2955, 2935, 1652, 1626,
.
1538, 1490, 1340, 1272, 1184, 1128, 990, 798, 758, 690 cmꢂ1
.
1H NMR (DMSO-d6): 0.93 (t, J ¼ 7.6 Hz, 3H, CH3), 1.30–
1.40 (m, 2H, CH2), 1.63–1.70 (m, 2H, CH2), 4.40 (t, J ¼ 7.6
Hz, 2H, CH2), 7.32–7.40 (m, 2H, ArH), 7.74 (t, J ¼ 8.8 Hz,
1H, ArH), 7.96 (d, J ¼ 8.0 Hz, 1H, ArH), 12.92 (s, 1H, NH).
3-(4-Chlorophenyl)-8-methyl-2-thioxo-2,3-dihydro-quinazo-
lin-4(1H)-one (3d). This compound was obtained as solid with
mp 186–188ꢁC (ref. 26; 182–184ꢁC); IR (KBr) m: 3275, 3144,
2974, 2873, 1704, 1699, 1616, 1524, 1492, 1410, 1213, 1090,
988, 795, 758, 736 cmꢂ1 1H NMR (DMSO-d6): 3.36 (s, 3H,
.
CH3), 7.27 (t, J ¼ 7.6 Hz, 1H, ArH), 7.33 (d, J ¼ 8.8 Hz, 2H,
ArH), 7.55 (d, J ¼ 8.8 Hz, 2H, ArH), 7.63 (d, J ¼ 7.2 Hz,
1H, ArH), 7.83 (d, J ¼ 7.6 Hz, 1H, ArH), 11.89 (s, 1H, NH).
3-Butyl-7-chloro-2-thioxo-2,3-dihydroquinazolin-4(1H)-one
(3e). This compound was obtained as solid with mp 232–
233ꢁC (ref. 25; 225–226ꢁC); IR (KBr) m: 3182, 3119, 2957,
2870, 1652, 1619, 1533, 1484, 1436, 1390, 1338, 1197, 1122,
2-Thioxo-3-m-tolyl-2,3-dihydroquinazolin-4(1H)-one (3a). This
compound was obtained as solid with mp 280–281ꢁC (ref.
Table 3
Synthesis of compounds 3 from N-substitued-o-nitrobenzamides 4 and
isothiocyanates 2.
946, 863, 765, 739 cmꢂ1
.
1H NMR (DMSO-d6): 0.93 (t, J ¼
7.2 Hz, 3H, CH3), 1.30–1.40 (m, 2H, CH2), 1.62–1.70 (m, 2H,
CH2), 4.37 (t, J ¼ 8.0 Hz, 2H, CH2), 7.36–7.40 (m, 2H, ArH),
7.96 (d, J ¼ 8.4 Hz, 1H, ArH), 12.96 (s, 1H, NH).
Y
R1
R
Yield (%)
3j
3k
3l
3m
3n
H
H
4-CH3OC6H4
4-BrC6H4
4-CH3C6H4
4-ClC6H4
C6H5
75
81
93
83
85
7-Chloro-3-(4-chlorophenyl)-2-thioxo-2,3–dihydro-quinazo-
lin-4(1H)-one (3f). This compound was obtained as solid with
mp 296–298ꢁC; IR (KBr) m: 3197, 3078, 3041, 2938, 1658,
1617, 1530, 1492, 1387, 1280, 1220, 1194, 1091, 925, 857,
H
CH3(CH2)7
4-ClC6H4CH2
C5H11
Cl
Cl
3-CH3C6H4
C6H5CH2
815, 758 cmꢂ1
.
1H NMR (DMSO-d6): 7.34 (d, J ¼ 8.4 Hz,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

942
M.-M. Wang, G.-L. Dou, and D.-Q. Shi
Vol 47
2H, ArH), 7.39 (dd, J ¼ 2.0 Hz, J ¼ 8.4 Hz, 1H, ArH), 7.46
1648, 1617, 1529, 1482, 1387, 1335, 1290, 1164, 1150, 1075,
948, 862, 762, 726 cmꢂ1 1H NMR (DMSO-d6): 5.64 (s, 2H,
.
CH2), 7.22–7.25 (m, 1H, ArH), 7.28–7.34 (m, 4H, ArH), 7.39
(d, J ¼ 8.4 Hz, 1H, ArH), 7.44 (s, 1H, ArH), 7.96 (d, J ¼ 8.4
Hz, 1H, ArH), 13.11 (s, 1H, NH).
1
2
(s, 1H, ArH), 7.55 (d, J ¼ 8.4 Hz, 2H, ArH), 7.95 (d, J ¼ 8.8
Hz, 1H, ArH), 13.13 (s, 1H, NH).
6-Chloro-3-phenyl-2-thioxo-2,3-dihydroquinazolin-4(1H)-
one (3g). This compound was obtained as solid with mp 293–
294ꢁC; IR (KBr) m: 3241, 3113, 3037, 2942, 1691, 1666,
1616, 1525, 1481, 1390, 1269, 1194, 1100, 993, 815, 772
2-amino-N-(4-methoxyphenyl)benzamide. This compound
was obtained as solid with mp 116–118ꢁC (ref. [30] 117–
118ꢁC); IR (KBr) m: 3400, 3330, 3250, 1640, 1604, 1535,
cmꢂ1
.
1H NMR (DMSO-d6): 7.28 (d, J ¼ 7.2 Hz, 2H, ArH),
1
7.42–7.51 (m, 4H, ArH), 7.83–7.89 (m, 2H, ArH), 13.15 (s,
1H, NH).
1507, 1429, 1220, 1160, 987, 752 cmꢂ1. H NMR (CDCl3-d6):
3.35 (s, 3H, OCH3), 5.02 (s, 2H, NH), 6.24 (t, J ¼ 8.0 Hz,
2H, ArH), 6.44 (d, J ¼ 8.8 Hz, 2H, ArH), 6.78 (t, J ¼ 8.4 Hz,
1H, ArH), 6.99 (d, J ¼ 8.8 Hz, 3H, ArH), 7.26 (s, 1H, NH).
6-Chloro-2-thioxo-3-m-tolyl-2,3-dihydroquinazolin-4(1H)-
one (3h). This compound was obtained as solid with mp 268–
270ꢁC; IR (KBr) m: 3243, 3037, 2890, 1663, 1617, 1524,
1
1482, 1387, 1270, 1222, 1200, 1100, 834, 771, 708 cmꢂ1. H
Acknowledgments. The authors are grateful to the Key Labora-
tory of Organic Synthesis of Jiangsu Province for financial
support.
NMR (DMSO-d6): 2.35 (s, 3H, CH3), 7.07 (d, J ¼ 8.8 Hz, 2H,
ArH), 7.23 (d, J ¼ 7.6 Hz, 1H, ArH), 7.37 (t, J ¼ 7.6 Hz, 1H,
ArH), 7.46 (d, J ¼ 8.8 Hz, 1H, ArH), 7.83–7.88 (m, 2H,
ArH), 13.14 (s, 1H, NH).
3-Butyl-6-chloro-2-thioxo-2,3-dihydroquinazolin 4(1H)-one
(3i). This compound was obtained as solid with mp 236–
237ꢁC; IR (KBr) m: 3249, 3040, 2965, 1650, 1621, 1528,
REFERENCES AND NOTES
1
1483, 1373, 1345, 1274, 1183, 1141, 1103, 828, 759 cmꢂ1. H
[1] Ismail, M. A. H.; Barker, S.; El Ella, D. A. A.; Abouzid, K.
A. M.; Toubar, R. A.; Todd, M. H. J Med Chem 2006, 49, 1526.
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[3] Choo, H.-Y. P.; Kim, M.; Lee, S. K.; Kim, S. W.; Chung, I.
K. Bioorg Med Chem 2002, 10, 517.
NMR (DMSO-d6): 0.93 (t, J ¼ 7.6 Hz, 3H, CH3), 1.30–1.39
(m, 2H, CH2), 1.62–1.69 (m, 2H, CH2), 4.37 (t, J ¼ 7.6 Hz,
2H, CH2), 7.39 (d, J ¼ 8.8 Hz, 1H, ArH), 7.79 (dd, J1 ¼ 2.0
Hz, J2 ¼ 8.4 Hz, 1H, ArH), 7.88 (d, J ¼ 2.0 Hz, 1H, ArH),
13.03 (s, 1H, NH).
[4] Buckley, G. M.; Davies, N.; Dyke, H. J.; Gilbert, P. J.;
Hannah, D. R.; Haughan, A. F.; Hunt, C. A.; Pitt, W. R.; Profit, R. H.;
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[5] Dreyer, D. L.; Brenner, R. C. Phytochemistry 1980, 19,
935.
2-Thioxo-3-p-tolyl-2,3-dihydroquinazolin-4(1H)-one (3j). This
compound was obtained as solid with mp 296–298ꢁC (ref. 25;
294–296ꢁC); IR (KBr) m: 3245, 3132, 3029, 2980, 1664, 1621,
1533, 1489, 1408, 1270, 1232, 1200, 990, 807, 759, 710 cmꢂ1
.
1H NMR (DMSO-d6): 2.38 (s, 3H, CH3), 7.14 (d, J ¼ 8.0 Hz,
2H, ArH), 7.28 (d, J ¼ 7.6 Hz, 2H, ArH), 7.35 (t, J ¼ 7.6 Hz,
1H, ArH), 7.45 (d, J ¼ 8.0 Hz, 1H, ArH), 7.79 (t, J ¼ 8.4 Hz,
1H, ArH), 7.95 (d, J ¼ 8.0 Hz, 1H, ArH), 13.02 (s, 1H, NH).
3-(4-Chlorophenyl)-2-thioxo-2,3-dihydroquinazolin-4(1H)-one
(3k). This compound was obtained as solid with mp >300ꢁC
(ref. 25; >300ꢁC); IR (KBr) m: 3246, 3138, 3038, 1664, 1621,
1532, 1489, 1407, 1268, 1234, 1201, 1094, 990, 812, 760, 737
[6] Alagarsamy, V.; Solomon, V. R.; Dhanabal, K. Bioorg Med
Chem 2007, 15, 235.
[7] Merck. Merck Index, Vol. 12; Merck: Whitehouse Station,
NJ, 1996; p 7897.
[8] Merck. Merck Index, Vol. 12; Merck: Whitehouse Station,
NJ, 1996; p 1512.
[9] Merck. Merck Index, Vol. 12; Merck: Whitehouse Station,
NJ, 1996; p 3489.
1
cmꢂ1. H NMR (DMSO-d6): 7.33–7.38 (m, 3H, ArH), 7.46 (d,
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761; (b) Kagara, K.; Goto, S.; Tsuboi, H. Jpn. Pat. 25,767,1989; Chem
Abstr 1989, 111, 97274.
J ¼ 8.8 Hz, 1H, ArH), 7.55 (d, J ¼ 8.4 Hz, 2H, ArH), 7.80 (t,
J ¼ 7.6 Hz, 1H, ArH), 7.96 (d, J ¼ 7.6 Hz, 1H, ArH), 13.09
(s, 1H, NH).
[11] Mohri, S. J Synth Org Chem Jpn 2001, 59, 514.
[12] (a) Pastor, G.; Blanchard, C.; Montginoul, C.; Torreilles, E.;
Giral, L.; Texier, A. Bull Soc Chim Fr 1975, 1331; (b) Khalifa, M.;
Osman, A. N.; Ibrahim, M. G.; Ossman, A. R. E.; Ismail, M. A. Phar-
mazie 1982, 37, 115.
3-Phenyl-2-thioxo-2,3-dihydroquinazolin-4(1H)-one (3l). This
compound was obtained as solid with mp 294–296ꢁC (ref. 25;
>300ꢁC); IR (KBr) m: 3246, 3137, 3029, 1662, 1623, 1533,
1489, 1406, 1267, 1227, 1197, 988, 843, 799, 760 cmꢂ1 1H
.
[13] Michman, M.; Patai, S.; Wiesel, Y. Org Prep Proced Int
1978, 10, 13.
NMR (DMSO-d6): 7.26–7.28 (m, 2H, ArH), 7.34–7.50 (m,
5H, ArH), 7.71–7.76 (m, 1H, ArH), 8.05 (d, J ¼ 8.0 Hz, 1H,
ArH), 13.09 (s, 1H, NH).
[14] Lange, N. A.; Sheibley, F. E. Org Synth 1943, 2, 79.
[15] Vorbrueggen, H.; Krolikiewicz, K. Tetrahedron 1994, 50,
6549.
7-Chloro-2-thioxo-3-m-tolyl-2,3-dihydroquinazolin-4(1H)-one
(3m). This compound was obtained as solid with mp 228–
230ꢁC (ref. 25; 230–232ꢁC); IR (KBr) m: 3190, 3074, 3021,
1660, 1616, 1526, 1479, 1417, 1385, 1258, 1193, 1073, 927,
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4439.
857, 803, 781, 757 cmꢂ1 1H NMR (DMSO-d6): 2.35 (s, 3H,
.
CH3), 7.08–7.10 (m, 2H, ArH), 7.25–7.27 (m, 1H, ArH),
7.33–7.35 (m, 2H, ArH), 7.45 (d, J ¼ 1.6 Hz, 1H, ArH), 7.95
(d, J ¼ 8.4 Hz, 1H, ArH), 13.01 (s, 1H, NH).
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3-Benzyl-7-chloro-2-thioxo-2,3-dihydroquinazolin-4(1H)-one
(3n). This compound was obtained as solid with mp 260–
262ꢁC (ref. 25; 255–257ꢁC); IR (KBr) m: 3204, 3127, 3041,
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

July 2010
One-Pot Synthesis of 2,3-Dihydro-2-thioxoquinazolin-4(1H)-ones from
Nitro-Compounds with the Aid of Tin(II) Chloride
943
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet