Synthesis and Antioxidant Evaluation of Quinoxalino[2′,3′:5,6][1,3,4]thiadiazino[2,3-b]quinazolin-15-ones: Derivatives of a Novel Ring System

Article abstract of DOI:10.1002/jhet.3078

Quinoxalino[2′,3′:5,6][1,3,4]thiadiazino[2,3-b]quinazolin-15-one, a novel fused heterocyclic system, was synthesized from a one-pot condensation reaction of 2,3-dichloroquinoxaline and 3-amino-2-thioxo-2,3-dihydroquinazolin-4(1H)-one under mild condition. Derivatization was performed on treatment of the titled compound with several alkyl bromides. In vitro antioxidant activity of the synthesized compounds was evaluated.

Full text of DOI:10.1002/jhet.3078

Month 2017
Synthesis and Antioxidant Evaluation of Quinoxalino[20,30:5,6][1,3,4]
thiadiazino[2,3-b]quinazolin-15-ones: Derivatives of a Novel Ring System
*
Mahsa Mousavi, Mehdi Bakavoli,
Ali Shiri,
and Hossein Eshghi
Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad 91775-1436, Iran
*
E-mail: mbakavoli@um.ac.ir; mbakavoli@yahoo.com
Received July 31, 2017
DOI 10.1002/jhet.3078
Published online 00 Month 2017 in Wiley Online Library (wileyonlinelibrary.com).
Quinoxalino[20,30:5,6][1,3,4]thiadiazino[2,3-b]quinazolin-15-one, a novel fused heterocyclic system, was
synthesized from a one-pot condensation reaction of 2,3-dichloroquinoxaline and 3-amino-2-thioxo-2,3-
dihydroquinazolin-4(1H)-one under mild condition. Derivatization was performed on treatment of the titled
compound with several alkyl bromides. In vitro antioxidant activity of the synthesized compounds was
evaluated.
J. Heterocyclic Chem., 00, 00 (2017).
INTRODUCTION
RESULTS AND DISCUSSION
Quinazolines and quinoxalines are pharmacologically
important motifs possessing a wide range of biological
and pharmaceutical activities. Quinoxalines are core units
in a number of medicines with diverse properties like
anticancer [1], antibacterial [2], antiviral [3], anti-HIV
[4], and anti-inflammatory [5]. Moreover, scientists have
already determined many therapeutic activities of
quinazolines including antibacterial [6], antivirus [7],
anti-cytotoxin [8], anticancer [9], antimalarial [10], anti-
spasm [11], anti-inflammation [12], and others. From the
synthetic point of view, treatment of 4-amino-1,
2,4-triazole-3-thiols with 2,3-dichloroquinoxalines in
refluxing ethanol [13,14] or in the presence of sodium
acetate under microwave irradiation [15] can afford the
bioactive [1,2,4]triazolo-thiadiazino[5,6-b]quinoxalines.
Thiadiazino[2,3-b]quinazolin-6-ones can also be obtained
from hetrocyclization of substituted quinazolines [16]
through a simple nucleophilic substitution reaction. A
literature survey disclosed that there are few examples
available on antioxidant evaluation of these bioactive
skeletons [17,18]. Obviously, combination of two or
more moieties into one can result in discovery of new
bioactive molecules with improved biological activities.
In this regard and in continuation of our previous
research in this field [19,20], we wish to report the
combination of quinazoline and quinoxaline moieties via
formation of a thiadiazine core to afford a novel
pentacyclic ring system. Antioxidant activity of the new
system and its derivatives was evaluated.
Chemistry.
As illustrated in Scheme 1, a synthetic
pathway was designed for preparation of the desired
pentacyclic compound (3) and its derivatives 4(a–f ). 2,3-
Dichloroquinoxaline (1) was conveniently synthesized
according to the previously published procedure [21].
3-Amino-2-thioxo-2,3-dihydroquinazolin-4(1H )-one (2)
was prepared from the reaction of methyl 2-
isothiocyanatobenzoate with hydrazine hydrate in diethyl
ether [22]. Reaction of compound 1 with 2, in a
mixture of dimethylformamide (DMF)/K2CO3 at 80°C,
afforded the 13H,15H-quinoxalino [20,30,5,6] [1,3,4]
thiadiazino[2,3-b]quinazolin-15-one (3), as the novel
pentacyclic system. In 1H NMR spectral analysis,
emerging a D2O-exchangeable signal at δ = 7.96 ppm
for NH group and a set of multiplet signals at
δ = 6.74–8.02 ppm belonging to the aromatic C-H
bonds properly implies to the formation of 3. Moreover,
detecting a molecular ion peak at m/z = 319 (M+), along
with the complimentary results of micro analytical data,
confirms the synthesis of the titled ring system. Further
treatment of compound 3 with various alkylbromides
in a mixture of DMF/ K2CO3 at 80°C, furnished the
substituted derivatives 4(a–f ).
Structural characterization of the newly synthesized
derivatives 4(a–f ) was fully accomplished through the
experimental spectroscopic and elemental analysis data.
As an example, 1H NMR spectrum of compound 4a
shows a triplet signal at δ = 1.36 ppm, a quartet signal at
δ = 4.23 ppm, and multiplet signals at δ = 7.03–8.1 ppm
© 2017 Wiley Periodicals, Inc.

M. Mousavi, M. Bakavoli, A. Shiri, and H. Eshghi
Vol 000
Scheme 1. The synthetic pathway for the preparation of compounds 4(a–f).
belonging to methyl, methylene, and aromatic hydrogens
of phenyl groups, respectively. Furthermore,
disappearance of the stretching vibrational band for N─H
bond at 3236 cmꢀ1 in infrared (IR) spectrum of 4a
indicates the successful alkylation of N─H group in the
ascorbic acid as the standard antioxidant. The evaluation
was performed at λ = 517 nm using ultraviolet–visible
spectrophotometer (UV-2100 RAY Leigh, Beijing,
China), according to the previously published method
[23]. The results are reported as the mean values standard
deviation of three independent experiments and are
presented as IC50 values in Table 1.
Scavenging property of ascorbic acid against DPPH
radical was completely significant. Heterocyclic derivatives
were ranked based on the inhibitory activities in the
following order 4f > 4d > 4e > 4c > 4b > 3 > 4a.
According to the proposed mechanism by Baciocchi et al.
[24], it seems that H-abstraction from the N─CH2 groups
and the stability of the resulting free radicals are the
main factors responsible for the observed differences
(Scheme 2). Antioxidant activity was improved with the
increase of the length of the alkyl side chain on compounds
4(a–e). Indeed, the n-pentyl and n-hexyl side chains
presented better activities as were predicted [25].
Compound 4f containing benzyl substituent shown the best
scavenging activity, it could be because of the more
effectively distribution of unpaired electron in the
final product. Emerging
a molecular ion peak at
m/z = 347 (M+) in Mass spectrum, in addition to the
micro analytical data assessments, fully supports the
molecular formula of C18H13N5OS for compound 4a.
Similar results were obtained for other derivatives 4(b–f).
Evaluation of antioxidant activity. Antioxidant activity
of all the synthesized compounds 3 and 4(a–f ) was
determined using DPPH free radical scavenging assay
at different concentrations and compared with that of
Table 1
Antioxidant evaluation of the synthesized compounds 3 and 4(a–f).
a
Products
IC50
Products
IC50
3
0.1020 0.0003
0.1187 0.0001
0.1016 0.0001
0.0708 0.0002
4d
4e
0.0536 0.0005
0.0594 0.0007
0.0525 0.0002
0.0224 0.0004
4a
4b
4c
4f
AAb
produced radicals (phenyl vs. alkyl). Compound
3
unexpectedly exhibited low DPPH radical inhibitory
activity, nevertheless, it possesses good H-donating
N─H bond.
aThe required concentrations of the compounds (μmol/mL) to inhibit 50%
of the radicals.
bAscorbic acid.
Scheme 2. The proposed mechanism of product oxidation by DPPH.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2017
Synthesis of Quinoxalino[20,30:5,6][1,3,4]thiadiazino[2,3-b]quinazolinones
CONCLUSION
145.8 (S─C(quinoxaline)═N), 147.5 (N─C═C─Hd), 152.0
(NH─C═N), 156.9 (S─C(quinazoline)═N), 162.7 (CO). FTIR
(KBr disk, νmax): 3236 [─NH], 2918 [─CH2], 1685
[─C═O], 1607[─C═N], 1548 [─C═N] cmꢀ1. MS (m/z)
319 (M+), 161 (M+- NH-quinazoline). Anal. Calcd for
C16H9N5OS: C, 60.18; H, 2.84; N, 21.93; S, 10.04. Found:
C, 60.09; H, 2.80; N, 21.85; S, 9.90.
13H,15H-quinoxalino[20,30:5,6][1,3,4]thiadiazino[2,3-b]
quinazolin-15-one (3), a novel fused pentacyclic system,
was synthesized in quantitative yield from a condensation
reaction between 2,3-dichloroquinoxaline (1) and 3-
amino-2-thioxo-2,3-dihydroquinazolin-4(1H)-one (2) in
DMF. The cyclization reaction is so facile and takes place
in one step, under mild conditions. More derivatives were
obtained on further treatment of the newly synthesized
compound (3) with several alkylbromides under the
similar conditions. Antioxidant activity of all synthesized
compounds was determined using the DPPH free radical
scavenging assay, and the results are reported.
General procedure for synthesis of 13-alkyl-13H,15H-
quinoxalino[20,30:5,6][1,3,4]thiadiazino[2,3-b]quinazolin-15-one
4(a–f ). To a mixture of compound (3) (1 mmol, 319 mg)
and K2CO3 (1 mmol, 138 mg) in DMF at room
temperature, was added appropriate alkylbromide
(1.2 mmol). The reaction was heated to 80°C for 4 h. After
the completion of reaction which was monitored by thin-
layer chromatography using n-hexane/ ETOAc (2:1) as
eluent, the mixture was cooled to room temperature, and
the solvent was removed under reduced pressure. The
residue was washed with water and further purified by
column chromatography to yield the desired products 4(a–f).
EXPERIMENTAL
Melting points were recorded on an Electrothermal
type 9200 melting point apparatus. The infrared spectra
were obtained on Avatar 370 Fourier transform infrared
(FTIR) Thermo Nicolet, and only noteworthy absorptions
were listed. The 1H NMR (300 MHz) and the 13C
NMR (75 MHz) spectra were recorded on a Bruker
Advance DRX-300 Fourier transformer spectrometer.
Chemical shifts were reported in ppm downfield from
tetramethylsilane as internal standard. The mass spectra
were scanned on a Varian Mat CH-7 at 70 eV. Elemental
analyses were performed on a Thermo Finnigan Flash EA
1112 microanalyzer.
13-Ethyl-13H,15H-quinoxalino[20,30:5,6][1,3,4]thiadiazino
[2,3-b]quinazolin-15-one (4a).
Yellow powder, yield =
68%; mp 215–218°C (decomposed); 1H NMR
(300 MHz, CDCl3, 25°C): δ 1.36 (t, 3H, J = 9 Hz, CH3),
4.23 (q, 2H, J = 12 Hz, J = 21 Hz, CH2─N), 7.03–7.08
(m, 2H, quinazoline-Hb,Hd), 7.29–7.36 (m, 2H,
0
0
quinoxaline-Hc ,Hd ), 7.43 (t, 2H, J = 9 Hz, quinoxaline-
0
0
Ha ,Hb ), 7.61 (t, 1H, J = 6 Hz, quinazoline-Hc), 8.17
(d, 1H, J = 9 Hz, quinazoline-Ha). 13C NMR (75 MHz,
CDCl3, 25°C);
δ
10.7 (CH3), 39.5 (CH2─N),
113.1 (quinazoline-C-Hb), 121.4 (quinazoline-C-Hd),
0
0
Synthesis
of
13H,15H-quinoxalino[20,30:5,6][1,3,4]
123.1 (quinoxaline-C-Hb ), 126.1 (quinoxaline-C-Hc ),
0
126.7 (quinazoline-C-Hc), 127.7 (quinoxaline-C-Ha ),
thiadiazino[2,3-b]quinazolin-15-one (3). To a mixture of
2,3-dichloroquinoxaline (1) (1 mmol, 197 mg) and 3-
amino-2-thioxo-2,3-dihydroquinazolin ꢀ4(1H)-one (2)
(1 mmol, 193 mg) in DMF at 80°C, was added K2CO3
(2 mmol, 276 mg). The reaction mixture was left stirring
at 80°C for 5 h and then cooled to room temperature. The
orange precipitate was filtered off and recrystallized from
DMF to yield the bright yellow powder 13H,15H-
quinoxalino[20,30:5,6][1,3,4]thiadiazino[2,3-b]quinazolin-
15-one (3). Yield = 73%; mp > 300°C; 1H NMR (300 MHz,
DMSO-d6, 25°C): δ 6.76 (t, 1H, J = 9 Hz, quinazoline-Hb),
6.99 (dd, 1H, J = 6 Hz, J = 3 Hz, quinazoline-Hd), 7.12
0
128.7 (quinoxaline-C-Hd ), 130.7 (quinazoline-C-Ha),
0
132.3
(C─CO),
133.9
(N─C═C─Ha ),
134.5
0
(N-C═C─Hd ), 137.5 (S─C(quinoxaline)═N), 145.7
(N─C═C─Hd),
146.3
(NH─C═N),
146.5
(S─C(quinazoline)═N), 157.2 (CO). FTIR (KBr disk, νmax):
2923
[─CH2],
1704
[─C═O],
1547[─C═N],
1527[─C═N] cmꢀ1. MS (m/z) 347 (M+), 318 (M+ ꢀ Et).
Anal. Calcd for C18H13N5OS: C, 62.23; H, 3.77; N,
20.16; S, 9.23. Found: C, 62.39; H, 3.86; N, 20.08; S, 9.03.
13-Propyl-13H,15H-quinoxalino[20,30:5,6][1,3,4]thiadiazino
[2,3-b]quinazolin-15-one (4b).
Yellow powder, yield =
63%; mp 180–183°C (decomposed); 1H NMR
(300 MHz, CDCl3, 25°C): δ 1.17 (t, 3H, J = 9 Hz, CH3),
1.84–1.97 (m, 2H, CH2), 4.23 (t, 2H, J = 6 Hz, CH2─N),
7.12–7.19 (m, 2H, quinazoline-Hb,Hd), 7.42 (m, 2H,
0
(t, 1H, J = 9 Hz, quinoxaline-Hc ), 7.19 (dd, 1H, J = 3 Hz,
0
J = 6 Hz, quinoxaline-Hd ), 7.34 (t, 1H, J = 6 Hz,
0
0
quinoxaline-Hb ), 7.40 (d, 1H, J = 9 Hz, quinoxaline-Ha ),
7.62 (t, 1H, J = 6 Hz, quinazoline-Hc), 7.96 (s, 1H,
D2O-exchangeable NH), 7.99 (dd, 1H, J = 3 Hz, J = 6 Hz,
quinazoline-Ha). 13C NMR (75 MHz, DMSO-d6, 25°C);
δ 119.6 (quinazoline-C-Hb), 120.9 (quinazoline-C-Hd),
0
0
quinoxaline-Hc ,Hd ), 7.54 (t, 2H, J = 6 Hz, quinoxaline-
0
0
Ha ,Hb ), 7.72 (t, 1H, J = 9 Hz, quinazoline-Hc), 8.29
(dd, 1H, 6,
J
=
J =
3, quinazoline-Ha). 13C
0
0
NMR (75 MHz, CDCl3, 25°C); δ 11.5 (CH3), 19.0
(CH2), 45.8 (CH2─N), 113.1 (quinazoline-C-Hb), 121.4
124.4 (quinoxaline-C-Hb ), 125.8 (quinoxaline-C-Hc ),
0
126.6 (quinazoline-C-Hc), 126.9 (quinoxaline-C-Ha ), 129.0
0
0
(quinazoline-C-Hd), 123.1 (quinoxaline-C-Hb ), 126.1
(quinoxaline-C-Hd ), 133.3 (quinazoline-C-Ha), 136.4
0
0
0
(quinoxaline-C-Hc ), 126.7 (quinazoline-C-Hc), 127.7
(C─CO), 142.5 (N─C═C─Ha ), 145.6 (N─C═C─Hd ),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. Mousavi, M. Bakavoli, A. Shiri, and H. Eshghi
Vol 000
(quinoxaline-C-Ha ), 128.7 (quinoxaline-C-Hd ), 130.7
318 (M+ ꢀ Pentyl). Anal. Calcd for C21H19N5OS: C,
64.76; H, 4.92; N, 17.98; S, 8.23. Found C, 64.81; H,
4.93; N, 17.91; S, 8.12.
0
0
(quinazoline-C-Ha),
132.3
134.5
145.7
(C─CO),
(N─C═C─Hd ),
133.9
137.5
146.1
0
0
(N─C═C─Ha ),
13-Hexyl-13H,15H-quinoxalino[20,30:5,6][1,3,4]thiadiazino
(S─C(quinoxaline)═N),
(N─C═C─Hd),
(NH─C═N), 146.5 (S─C(quinazoline)═N), 157.2 (CO).
FTIR (KBr disk, νmax): 2920 [─CH2], 1698 [─C═O],
1545 [─C═N], 1526 [─C═N] cmꢀ1. MS (m/z) 361 (M+),
318 (M+ ꢀ Pr). Anal. Calcd for C19H15N5OS: C, 63.14;
H, 4.18; N, 19.38; S, 8.87. Found: C, 63.29; H, 4.11; N,
19.41; S, 8.79.
[2,3-b]quinazolin-15-one (4e).
Yellow powder, yield =
48%; mp 119–123°C (decomposed); 1H NMR
(300 MHz, CDCl3, 25°C): δ 0.84 (t, 3H, J = 6 Hz, CH3),
1.18–1.27 (m, 4H, 2CH2), 1.44–1.49 (m, 2H, CH2),
1.68–1.80 (m, 2H, CH2), 4.12 (t, 2H, J = 4 Hz, CH2─N),
7.02 (t, 2H, J = 6 Hz, quinazoline-Hb,Hd), 7.26–7.48 (m,
13-Butyl-13H,15H-quinoxalino[20,30:5,6][1,3,4]thiadiazino
0
0
0
0
4H, quinoxaline-Hc ,Hd , Ha ,Hb ), 7.69 (t, 1H, J = 3 Hz,
quinazoline-Hc), 8.17 (d, 1H, J = 6 Hz, quinazoline-Ha).
13C NMR (75 MHz, CDCl3, 25°C); δ 14.0 (CH3),
22.6 (CH2─Me), 25.5 (CH2─Et), 26.7 (CH2─Pr), 31.5
(CH2─Bu), 44.4 (CH2─N), 113.3 (quinazoline-C-Hb),
[2,3-b]quinazolin-15-one (4c).
Yellow powder, yield =
61%; mp 148–152°C (decomposed); 1H NMR
(300 MHz, CDCl3, 25°C): δ 1.06 (t, 3H, J = 6 Hz, CH3),
1.54–1.64 (m, 2H, CH2), 1.78 (m, 2H, CH2), 4.25 (t, 2H,
J = 6 Hz, CH2─N), 7.14 (t, 2H, J = 9 Hz, quinazoline-
0
121.4 (quinazoline-C-Hd), 123.0 (quinoxaline-C-Hb ),
0
0
Hb,Hd), 7.41 (m, 2H, quinoxaline-Hc ,Hd ), 7.52 (t, 2H,
0
126.1 (quinoxaline-C-Hc ), 126.6 (quinazoline-C-Hc),
0
0
J = 9 Hz, quinoxaline-Ha ,Hb ), 7.70 (t, 1H, J = 6 Hz,
quinazoline-Hc), 8.27 (d, 1H, J = 9 Hz, quinazoline-Ha).
13C NMR (75 MHz, CDCl3, 25°C); δ 13.8 (CH3), 20.3
(CH2─Me), 27.6 (CH2─Et), 44.15 (CH2─N), 113.3
(quinazoline-C-Hb), 121.4 (quinazoline-C-Hd), 123.0
0
0
127.6 (quinoxaline-C-Ha ), 128.7 (quinoxaline-C-Hd ),
130.6 (quinazoline-C-Ha), 132.6 (C─CO), 133.8
0
0
(N─C═C─Ha ),
134.4
(N─C═C─Hd ),
137.7
(S─C(quinoxaline)═N), 145.7 (N─C═C─Hd), 146.3
(NH─C═N), 146.5 (S─C(quinazoline)═N), 157.1 (CO).
FTIR (KBr disk, νmax): 2926 [─CH2], 1707 [─C═O],
1549 [─C═N], 1529 [─C═N] cmꢀ1. MS (m/z) 403 (M+),
318 (M+ ꢀ Hexyl). Anal. Calcd for C22H21N5OS: C,
65.49; H, 5.25; N, 17.36; S, 7.95. Found C, 65.51; H,
5.30; N, 17.33; S, 7.90.
0
0
(quinoxaline-C-Hb ), 126.1 (quinoxaline-C-Hc ), 126.7
(quinazoline-C-Hc), 127.6 (quinoxaline-C-Ha ), 128.7
(quinoxaline-C-Hd ), 130.6 (quinazoline-C-Ha), 132.6
0
0
0
0
(C─CO), 133.8 (N─C═C─Ha ), 134.4 (N─C═C─Hd ),
137.8 (S─C(quinoxaline) = N), 145.7 (N─C═C─Hd), 146.2
(NH─C═N), 146.6 (S─C(quinazoline)═N), 157.2 (CO).
FTIR (KBr disk, νmax): 2922 [─CH2], 1708 [─C═O],
1547 [─C═N], 1527 [─C═N] cmꢀ1. MS (m/z) 375 (M+),
318 (M+ ꢀ Bu). Anal. Calcd for C20H17N5OS: C, 63.98;
H, 4.56; N, 18.65; S, 8.54. Found C, 63.90; H, 4.67; N,
18.71; S, 8.40.
13-Benzyl-13H,15H-quinoxalino[20,30:5,6][1,3,4]thiadiazino
[2,3-b]quinazolin-15-one (4f ).
Yellow powder, yield =
69%; mp 153–156°C (decomposed); 1H NMR
(300 MHz, CDCl3, 25°C): δ 5.46 (s, 2H, CH2─N), 7.2
(s, 5H, Bz), 7.47 (t, 1H, J = 9 Hz, quinazoline-Hb), 7.57
(d, 1H, J = 9 Hz, quinazoline-Hd), 7.67–7.78 (m, 3H,
13-Pentyl-13H,15H-quinoxalino[20,30:5,6][1,3,4]thiadiazino
[2,3-b]quinazolin-15-one (4d).
quinoxaline-Hc , Hd , Hb ), 8.02 (t, 2H, J = 12 Hz, Ha ,
Hc), 8.28 (d, 1H, J = 9 Hz, quinazoline-Ha). 13C
NMR (75 MHz, CDCl3, 25°C); δ 55.75 (CH2-Ph),
121.6 (quinazoline-C-Hb), 126.4 (quinazoline-C-Hd),
0
0
0
0
Yellow powder, yield =
54%; mp 133–136°C (decomposed); 1H NMR (300 MHz,
CDCl3, 25°C): δ 0.88 (t, 3H, J = 6 Hz, CH3), 1.37–1.48
(m, 4H, 2CH2), 1.64–1.81 (m, 2H, CH2), 4.12 (t, 2H,
J = 6 Hz, CH2─N), 7.01 (t, 2H, J = 9, quinazoline-Hb,
0
0
126.9 (quinoxaline-C-Hb ), 127.2 (quinoxaline-C-Hc ),
128.1 (Bz), 128.3 (Bz), 128.5 (quinazoline-C-Hc),
0
0
Hd), 7.19–7.33 (m, 2H, quinoxaline-Hc ,Hd ), 7.36–7.43
0
0
128.8 (quinoxaline-C-Ha ), 128.9 (quinoxaline-C-Hd ),
0
0
(m, 2H, quinoxaline-Ha ,Hb ), 7.58 (t, 1H, J = 4 Hz,
quinazoline-Hc), 8.15 (d, 1H, J = 9, quinazoline-Ha). 13C
NMR (75 MHz, CDCl3, 25°C); δ 14.0 (CH3), 22.4
130.5 (quinazoline-C-Ha), 134.5 (C─CO), 134.9
0
0
(N─C═C─Ha ), 139.5 (N─C═C─Hd ), 140.2 (Bz),
145.7 (S─C(quinoxaline)═N), 146.1 (N─C═C─Hd), 148.7
(NH─C═N), 153.2 (S─C(quinazoline)═N), 157.9 (CO).
FTIR (KBr disk, νmax): 2925 [─CH2], 1695 [─C═O],
1578 [─C═N], 1556 [─C═N] cmꢀ1. MS (m/z) 409 (M+),
302 (M+ ꢀ NBz). Anal. Calcd for C23H15N5OS: C,
67.47; H, 3.69; N, 17.10; S, 7.83. Found C, 67.43; H,
3.58; N, 17.19; S, 7.69.
(CH2─Me),
25.2
(CH2─Et),
29.1
(CH2─Pr),
44.3 (CH2─N), 113.3 (quinazoline-C-Hb), 121.4
(quinazoline-C-Hd), 123.0 (quinoxaline-C-Hb ), 126.0
(quinoxaline-C-Hc ), 126.6 (quinazoline-C-Hc), 127.6
(quinoxaline-C-Ha ), 128.6 (quinoxaline-C-Hd ), 130.6
0
0
0
0
(quinazoline-C-Ha),
132.5
134.4
(C─CO),
(N─C═C─Hd ),
133.8
137.7
0
0
(N─C═C─Ha ),
(S─C(quinoxaline)═N), 145.7 (N─C═C─Hd), 146.2
(NH─C═N), 146.5 (S─C(quinazoline)═N), 157.1 (CO).
FTIR (KBr disk, νmax): 2920 [─CH2], 1708 [─C═O],
1548 [─C═N], 1529 [─C═N] cmꢀ1. MS (m/z) 389 (M+),
Acknowledgments. The authors gratefully acknowledge the
Research Council of Ferdowsi University of Mashhad as the
funder of this project for its partial financial support (3/33579).
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2017
Synthesis of Quinoxalino[20,30:5,6][1,3,4]thiadiazino[2,3-b]quinazolinones
[15] Shiradkar, M. R.; Padhalingappa, M. B.; Bhetalabhotala, S.;
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Additional Supporting Information may be found online
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet