Novel and efficient synthesis of substituted quinoline-1-oxides and the complex compounds SnL2Cl2 (L=2-aminoquinoline-1-oxides) with the aid of stannous chloride

Article abstract of DOI:10.1016/j.tet.2012.07.049

A novel and efficient approach to the synthesis of substituted quinoline-1-oxides and the complex compounds SnL₂Cl₂ (L=2-aminoquinoline-1-oxides) was developed. The reaction has fancy selectivity when 3-(2-nitrophenyl)acrylonitriles were treated with the aid of SnCl ₂ reagent under the same conditions. When R is -CN or -COOR′ the complex compounds SnL₂Cl₂ (L=2-aminoquinoline-1- oxides) were obtained. Whereas, when R is H or aryl another series of substituted quinoline-1-oxides were formed. The products have been screened for their anticancer activities.

Full text of DOI:10.1016/j.tet.2012.07.049

Tetrahedron 68 (2012) 7782e7786
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Tetrahedron
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Novel and efficient synthesis of substituted quinoline-1-oxides and the complex
compounds SnL2Cl2 (L¼2-aminoquinoline-1-oxides) with the aid of stannous
chloride
*
Lei Fu, Wei Lin, Pan Xu, Yu-Kun Xi, Man-Man Wang, Da-Qing Shi
Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel and efficient approach to the synthesis of substituted quinoline-1-oxides and the complex
compounds SnL2Cl2 (L¼2-aminoquinoline-1-oxides) was developed. The reaction has fancy selectivity
when 3-(2-nitrophenyl)acrylonitriles were treated with the aid of SnCl2 reagent under the same
conditions. When R is eCN or eCOOR0 the complex compounds SnL2Cl2 (L¼2-aminoquinoline-1-oxides)
were obtained. Whereas, when R is H or aryl another series of substituted quinoline-1-oxides were
formed. The products have been screened for their anticancer activities.
Received 31 December 2011
Received in revised form 5 July 2012
Accepted 13 July 2012
Available online 21 July 2012
Keywords:
Quinoline-1-oxides
Synthesis
Ó 2012 Elsevier Ltd. All rights reserved.
Stannous chloride
1. Introduction
Moreover, quinoline-N-oxides can also be prepared using molecular
sieve15 or urea hydrogen peroxide16 as catalysts. However, these
Quinoline-N-oxide is an important class of quinoline
derivatives. The quinoline-N-oxide core unit has been found in
drugs exerting microsomal Na, K-ATPase activity,1 protein kinase
inhibition and anticancer,2 antiviral3 or antimalarian activities.4,5
They have also relevant applications as spin traps in biological
studies,6 and are efficient in age-related diseases,7 due to both
in vitro and in vivo8 stability of resulting nitroxide radicals.
Metal complexes have a massive impact on medicine. They are
attractive candidates for the design of new anticancer agents. Cis-
platin, carboplatin and oxaloplatin were the first clinically used
antitumour drugs. Some diorganotin(IV) complexes were found to
have even better activity than cisplatin, which made them suitable
candidates for possible clinical use.9
methods suffer from some disadvantages, such as drastic conditions,
unsatisfactory yields, long-reaction time, complex manipulation and
inaccessible starting materials. Therefore, the development of more
efficient methods for preparing this kind of compounds with milder
reaction conditions and improved yields is highly desired.
In recent years, our interest has been focused on the synthesis of
heterocyclic compounds using SnCl2 as reductive reagent.17e22 We
havepreviouslyreportedthesynthesisof1-hydroxy-quinazolinones17
via the reaction of 2-nitrobenzamides with ketones induced by SnCl2.
As our earlier works goes, herein, we report a novel and convenient
protocol for the synthesis of substituted quinolin-1-oxides using 3-(2-
nitrophenyl)acrylonitriles as starting materials induced by SnCl2.
The importance of quinoline-N-oxides has stimulated the de-
velopment of a number of approaches for the synthesis of the quin-
oline-N-oxide ring system. Kim et al. have reported the synthesis of 3-
substituted-4-hydroxyquinoline-N-oxides from the BayliseHillman
adducts ofo-nitrobenzaldehydes.10,11 Makosza et al. have synthesized
substituted quinoline-N-oxides and 3,4-dihydroquinoline-N-oxides
via reductive cyclization of alkylidene o-nitroarylacetonitriles12 and
2-phenyl-2-(o-nitrobenzyl)-alkanenitriles,13 respectively. Recently
Lamaty et al. have synthesized a novel pyrrolo[3,2-c]quinoline-N-
oxide by aza-BayliseHillman adduct of o-nitrobenzaldehyde.14
2. Results and discussion
In a preliminary study, 2-(2-nitrobenzylidene)malononitrile 1a
was chosen as starting material for synthesis of 2-amino-3-
cyanoquinoline-1-oxide (Scheme 1). We proceeded this reaction in
EtOH at reflux in the presence of 3 equiv of SnCl2$2H2O. To our sur-
prise, the expected product 2-amino-3-cyanoquinoline-1-oxide was
not detected, while an unidentified product was obtained. Later, the
unidentified product was identified to be the complex compound 2a
by their 1H NMR and HRMS spectra. So a protocol for the synthesis of
the complex compounds SnL2Cl2 (L¼2-aminoquinoline-1-oxides)
was developed. The reaction conditions were optimized by testing
several parameters. The results were summarized in Table 1.
* Corresponding author. E-mail address: dqshi@263.net (D.-Q. Shi).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.07.049

L. Fu et al. / Tetrahedron 68 (2012) 7782e7786
7783
Scheme 1. The synthesis of the compound 2a.
Table 1
Table 2
Optimization for the synthesis of 2a
Synthesis of the complex compounds SnL2Cl2 (L¼2-aminoquinoline-1-oxides) 2
Entry Reductive reagent Ratioa Temperature (ꢀC) Solvent Time (h) Yieldb (%)
Entry
Products
X
Y
R
Isolated yield (%)
1
2
3
4
5
6
7
8
SnCl2$2H2O
SnCl2$2H2O
SnCl2$2H2O
SnCl2$2H2O
SnCl2$2H2O
SnCl2$2H2O
SnCl2$2H2O
SnCl2$2H2O
SnCl2$2H2O
SnCl2$2H2O
ZnþHOAc
1:3
1:3
1:3
1:3
1:3
1:3
1:3
1:1
1:2
1:4
1:3
rt
40
60
Reflux
60
60
60
60
60
EtOH
EtOH
EtOH
EtOH
THF
CHCl3
DMF
EtOH
EtOH
EtOH
EtOH
3
2
2
2
2
2
2
4
4
2
2
34
54
87
88
61
56
23
25
40
83
80c
1
2
3
4
5
6
7
8
2a
2b
2c
2d
2e
2f
H
H
H
H
H
H
H
H
H
CN
87
83
85
84
77
80
72
79
COOCH(CH3)2
COOCH3
COOC2H5
COOC2H5
COOCH(CH3)2
CN
Cl
H
Cl
Cl
Cl
2g
2h
OCH2O
COOC2H5
9
10
11
60
60
a
withdrawing groups (such as halide groups) or electron-donating
groups (such as alkyl groups) under the same conditions to give
moderate to good yields.
Ratio of 1a and SnCl2$2H2O system.
Isolated yield.
The yield of 2-amino-3-cyanoquinoline.
b
c
However, to our surprise the complex compounds SnL2Cl2 (L¼2-
aminoquinoline-1-oxides) were not obtained when R was aryl or H
groups. Instead we obtained a series of novel compounds, which
were identified as quinoline-1-oxides 2 (Scheme 3, Table 3).
As shown in Table 1, we briefly examined the effect of different
temperatures, different solvents and ratio of 1a:SnCl2$2H2O. The
results showed that at 60 ꢀC the reaction proceeded smoothly in
high yield. In order to further evaluate the influence of the ratio of
1a/SnCl2$2H2O, the reaction was carried out in ethanol using a 1:1
to 1:4 ratio of 1a/SnCl2$2H2O (Table 1, entries 8, 9, 3, 10), leading to
2a in 25%, 40%, 87% and 83% yields, respectively. We concluded the
best ratio of 1a:SnCl2$2H2O was 1:3. Moreover, other organic sol-
vents were further investigated as shown in Table 1 (entries 5e7),
we concluded that ethanol was the best solvent for this reaction. It
is indicated that the reductive agent is very important for the
synthesis of 2a. When compound 2a was reduced by Zn in HOAc,
only 2-amino-3-cyanoquinoline was obtained (Table 1, entry 11).
Withthe optimized conditionsinhand, wethenperformed amore
detailed examination of the substrates. We found that when R was CN
or COOR0, the desired products SnL2Cl2 (L¼2-aminoquinoline-N-ox-
ides) were obtained (Scheme 2). The results were summarized in
Table 2.
Scheme 3. The synthesis of quinoline-1-oxides 3.
Similarly, 3-(2-nitrophenyl)acrylonitriles 1 containing electron-
donating and electron-withdrawing substituents were reacted well
under the same conditions. Therefore, we can conclude that the
electronic nature of the substituents has no significant effect on this
reaction.
As shown inTable 2, it can be seen that this protocol can be applied
to 3-(2-nitrophenyl)-acrylonitriles
1
with either electron-
Scheme 2. The synthesis of SnL2Cl2 (L¼2-aminoquinoline-1-oxides) 2.

7784
L. Fu et al. / Tetrahedron 68 (2012) 7782e7786
Table 3
1 were reduced by tin(II) chloride to corresponding hydroxylamine
Synthesis of the quinoline-1-oxides 3
compounds A and Sn(II) was oxidated to Sn(IV). The hydroxylamine
compounds A then reacted with cyano group by intramolecular cy-
clization to give the intermediate B. Another intermediate C was
formed by tautomerization of intermediate B. When R¼H or aryl, the
intermediate C was not stable and reacted with water to give the
products 3. When R¼CN or COOR0, the intermediate C was stable and
coordinated with Sn(IV) to give the complex compounds 2.
Finally, the synthetic compounds were screened for anticancer
activity by the sulforhodamine B (SRB) method. The cells used in
this study were human liver cancer cell line HepG2. The results of
the prescreening are listed in Table 4. It could be seen that only
some products (e.g., 2f, 3c and 3d) had weak anticancer activity.
Entry
Products
X
Y
R
Isolated yield (%)
1
2
3
4
5
6
7
8
3a
3b
3c
3d
3e
3f
H
H
H
H
H
Cl
CH3O
CH3O
CH3O
4-ClC6H4
C6H5
4-ClC6H4
C6H5
4-ClC6H4
4-BrC6H4
C6H5
70
80
83
84
76
70
71
74
CH3O
CH3O
CH3O
OCH2O
H
3g
3h
H
H
All the products were characterized by IR, 1H NMR and HRMS
spectra. The structure of 2e was further confirmed by X-ray dif-
fraction analysis.23 The molecular structure of the product 2e is
shown in Fig. 1.
Fig. 1. Molecular structure of product 2e.
Although the detailed mechanism of the above reaction has not
been clarified yet, the formation of 2-aminoquinoline-1-oxide de-
rivatives 2 or 3 can beexplained bya possible mechanism presented in
Scheme 4. In the initial step, 3-(2-nitrophenyl)acrylonitrile derivatives
3. Conclusion
In summary, we have described a novel and efficient method for
the synthesis of highly functionalized quinolin-1-oxides and complex
Scheme 4. Proposed reaction mechanism.

L. Fu et al. / Tetrahedron 68 (2012) 7782e7786
7785
1303, 1220, 1039, 787, 764, 625 cmꢁ1
.
1H NMR (400 MHz, DMSO-
Table 4
Survival rate of compounds 2 and 3 in 30
m
m on HepG2 cells
Compound
d6): dH 1.45 (t, J¼7.6 Hz, 6H, 2ꢂ CH3), 4.47e4.53 (m, 4H, 2ꢂ CH2),
7.54 (t, J¼7.2 Hz, 2H, ArH), 7.90 (t, J¼8.0 Hz, 2H, ArH), 7.99 (d,
J¼8.4 Hz, 2H, ArH), 8.21 (d, J¼8.4 Hz, 2H, ArH), 8.80 (s, 2H, 2ꢂ NH),
8.99 (s, 2H, ArH). HRMS found: m/z 651.9941 (Mþ), calcd for
C24H22N4O635Cl2Sn: M, 651.9938.
Compound
Survival rate
Survival rate
2a
2b
2c
2d
2e
2f
1.005822
1.262193
0.947602
0.994587
1.098769
0.607987
1.007865
0.936878
3a
3b
3c
3d
3e
3f
0.911343
0.961391
0.780358
0.773887
0.947469
0.870194
0.966882
1.112676
4.2.5. Compound 2e. White solid; mp: 274e276 ꢀC; IR (KBr)
n: 3344,
3048, 2964, 2937,1708,1672,1616,1599,1519,1418,1368,1286,1182,
1083, 1036, 821, 786, 694 cmꢁ1. 1H NMR (400 MHz, DMSO-d6): dH
1.43 (t, J¼7.2 Hz, 6H, 2ꢂ CH3), 4.49 (dd, J1¼14 Hz, J2¼6.8 Hz, 4H, 2ꢂ
CH2), 7.88 (d, J¼9.2 Hz, 2H, ArH), 7.97 (d, J¼8.4 Hz, 2H, ArH), 8.35 (s,
2H, ArH), 8.84 (s, 2H, 2ꢂ NH), 8.95 (s, 2H, ArH). HRMS found: m/z
719.9167 (Mþ), calcd for C24H20N4O635Cl4Sn: M, 719.9159.
2g
2h
3g
3h
compounds SnL2Cl2 (L¼2-aminoquinoline-1-oxides). Our protocol is
characterized by (i) faster reaction times (1e2 h) and moderate to
highyields, (ii)handymanipulation(onlyonepot)and(iii)isolationof
products via simple recrystallization to give higher purities.
4.2.6. Compound 2f. White solid; mp: 207e210 ꢀC; IR (KBr)
n: 3341,
3058, 2982, 1707, 1618, 1570, 1522, 1418, 1365, 1283, 1206, 1150,
1030, 938, 787, 626 cmꢁ1. 1H NMR (400 MHz, DMSO-d6): dH 1.44 (d,
J¼6.0 Hz,12H, 4ꢂ CH3), 5.28e5.34 (m, 2H, 2ꢂ CH), 7.88 (d, J¼9.2 Hz,
2H, ArH), 7.97 (d, J¼8.8 Hz, 2H, ArH), 8.37 (s, 2H, ArH), 8.87 (s, 2H,
2ꢂ NH), 8.93 (s, 2H, ArH). HRMS found: m/z 747.9477 (Mþ), calcd for
C26H24N4O635Cl4Sn: M, 747.9472.
4. Experimental section
4.1. General
Commercial solvents and reagents were used as received. Melting
points are uncorrected. IR spectra were recorded on Varian F-1000
4.2.7. Compound 2g. White solid; mp: >300 ꢀC; IR (KBr)
n: 3304,
spectrometer in KBr with absorptions in cmꢁ1 1H NMR was de-
.
3041, 2928, 2854, 2236, 1666, 1617, 1602, 1575, 1526, 1416, 1365,
1210, 1036, 944, 836, 652 cmꢁ1. 1H NMR (400 MHz, DMSO-d6): dH
7.90e7.99 (m, 4H, ArH), 8.12 (s, 2H, ArH), 8.82 (s, 2H, ArH), 9.45 (s,
2H, 2ꢂ NH). HRMS found: m/z 625.8646 (Mþ), calcd for
C20H10N6O235Cl4Sn: M, 625.8641.
termined on Varian-400 MHz or Varian-300 MHz spectrometer in
DMSO-d6 solution. J values are in hertz. Chemical shifts are expressed
in parts per million downfield from internal standard TMS. HRMS data
were obtained using microma GCT-TOF instrument. X-ray crystallo-
graphic analysis was performed with a Rigaku Mercury CCD/AFC
diffractometer.
4.2.8. Compound 2h. White solid; mp: 262e264 ꢀC; IR (KBr):
3344, 3130, 3058, 2981, 2907, 1699, 1623, 1597, 1535, 1438, 1373,
1250, 1217, 1034, 991, 938, 785, 629 cmꢁ1 1H NMR (300 MHz,
n
4.2. General procedure for the synthesis of 2 and 3 is repre-
sented as follows
.
DMSO-d6): dH 1.38 (t, J¼7.2 Hz, 6H, 2ꢂ CH3), 4.39e4.46 (m, 4H, 2ꢂ
CH2), 6.23 (s, 4H, 2ꢂ OCH2O), 7.34 (s, 2H, 2ꢂ NH), 7.61 (s, 2H, ArH),
8.56 (s, 2H, ArH), 8.74 (s, 2H, ArH). HRMS found: m/z 739.9767 (Mþ),
calcd for C26H22N4O1035Cl2Sn: M, 739.9735.
A
solution of 3-(2-nitrophenyl)acrylonitrile derivatives 1
(1 mmol) and SnCl2$2H2O (3 mmol) in EtOH (5 mL) was stirred at
60 ꢀC for 1e2 h. After this period, 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 puri-
fied by recrystallization from 95% ethanol and DMF.
4.2.9. 2-Amino-3-(4-chlorophenyl)quinoline-1-oxide
solid;mp:>300 ꢀC;IR (KBr)
: 3418, 3068, 3045,1715,1621,1580,1516,
1481, 1453, 1358, 1183, 1094, 903, 836, 754, 632 cmꢁ1 1H NMR
(3a). White
n
.
(300 MHz, DMSO-d6): dH 6.22 (s, 1H, NH), 7.26 (s, 1H, ArH), 7.39 (t,
J¼5.7 Hz, 1H, ArH), 7.54 (d, J¼8.8 Hz, 2H, ArH), 7.57 (d, J¼8.4 Hz, 2H,
ArH), 7.66e7.68 (m, 1H, ArH), 7.70e7.73 (m, 2H, ArHþNH), 8.22 (d,
J¼6.3 Hz, 1H, ArH). HRMS found: m/z 270.0563 (Mþ), calcd for
C15H11N2O35Cl: M, 270.0560.
4.2.1. Compound 2a. White solid; mp: >300 ꢀC. IR (KBr)
n: 3309,
3046, 2235,1619,1602,1577,1529,1453,1343,1287,1230,1212,1042,
942, 873, 761, 619 cmꢁ1. 1H NMR (400 MHz, DMSO-d6): dH 7.54 (t,
J¼7.6 Hz, 2H, ArH), 7.92 (t, J¼8.0 Hz, 2H, ArH), 7.98e8.02 (m, 4H,
ArH), 8.91 (s, 2H, ArH), 9.25 (s, 2H, 2ꢂ NH). HRMS found: m/z
557.9428 (Mþ), calcd for C20H12N6O235Cl2Sn: M, 557.9421.
4.2.10. 2-Amino-3-phenylquinoline-1-oxide (3b). White solid; mp:
>300 ꢀC; IR (KBr)
n: 3423,3050, 2928,1670,1621,1515,1482, 1358, 1211,
1
4.2.2. Compound 2b. White solid; mp: 226e227 ꢀC; IR (KBr)
n: 3343,
1189, 1154, 1006, 915, 775, 759, 661, 630 cmꢁ1. H NMR (300 MHz,
DMSO-d6): dH 7.47 (t, J¼7.5 Hz, 1H, ArH), 7.54e7.62 (m, 5H, ArH),
7.74e7.85 (m, 2H, ArH), 7.95e8.02 (m, 2H, ArH), 8.07e8.11 (m, 2H,
NH2). HRMS found: m/z 236.0960 (Mþ), calcd for C15H12N2O: M,
236.0950.
2983, 2934, 1701, 1621, 1603, 1576, 1528, 1457, 1364, 1301, 1221, 1184,
1100,1036, 788, 759, 625 cmꢁ1.1H NMR (400 MHz, DMSO-d6): dH 1.45
(d, J¼6.4 Hz,12H, 4ꢂ CH3), 5.28e5.35 (m, 2H, 2ꢂ CH), 7.54 (t, J¼7.6 Hz,
2H, ArH), 7.90 (t, J¼8.0 Hz, 2H, ArH), 7.99(d, J¼8.4 Hz,2H, ArH), 8.21(d,
J¼8.0 Hz, 2H, ArH), 8.84 (s, 2H, 2ꢂ NH), 8.96 (s, 2H, ArH). HRMS found:
m/z 680.0251 (Mþ), calcd for C26H26N4O635Cl2Sn: M, 680.0251.
4.2.11. 2-Amino-6-chloro-3-(4-chlorophenyl)quinoline-1-oxide
(3c). White solid; mp: 241e243 ꢀC; IR (KBr)
n: 3416, 3046, 2928,
4.2.3. Compound 2c. White solid; mp: >300 ꢀC; IR (KBr)
n
: 3337,
2854, 1675, 1510, 1418, 1211, 1182, 1089, 923, 836, 730, 634 cmꢁ1. 1H
NMR (300 MHz, DMSO-d6): dH 7.57e7.65 (m, 4H, ArH), 7.74e7.83 (m,
2H, ArH), 7.92e7.98 (m, 2H, NH2), 8.01e8.05 (m, 2H, ArH). HRMS
found: m/z 304.0178 (Mþ), calcd for C15H10N2O35Cl2: M, 304.0170.
3057, 2954,1708,1615,1599,1570,1522,1438,1364,1288,1206,1183,
1035, 836, 786, 633 cmꢁ1. 1H NMR (400 MHz, DMSO-d6): dH 4.03 (s,
6H, 2ꢂ CH3), 7.89 (d, J¼8.4 Hz, 2H, ArH), 7.97 (d, J¼8.4 Hz, 2H, ArH),
8.35 (s, 2H, ArH), 8.81 (s, 2H, 2ꢂ NH), 8.96 (s, 2H, ArH). HRMS found:
m/z 691.8848 (Mþ), calcd for C22H16N4O635Cl4Sn: M, 691.8846.
4.2.12. 2-Amino-6,7-dimethoxy-3-phenylquinoline-1-oxide
(3d). White solid; mp: >300 ꢀC; IR (KBr)
n: 3418, 3049, 2999, 2831,
4.2.4. Compound 2d. White solid; mp: 297e299 ꢀC; IR (KBr)
3334, 3088, 3056, 2993, 2908, 1699, 1619, 1575, 1524, 1456, 1368,
n
:
1669, 1611, 1515, 1446, 1409, 1267, 1163, 986, 828, 715, 688 cmꢁ1. 1H
NMR (300 MHz, DMSO-d6): dH 3.84 (s, 3H, CH3O), 3.89 (s, 3H,

7786
L. Fu et al. / Tetrahedron 68 (2012) 7782e7786
CH3O), 7.27 (s, 1H, ArH), 7.44 (s, 2H, ArH), 7.52e7.60 (m, 5H, ArH),
7.93e7.97 (m, 2H, NH2). HRMS found: m/z 296.1158 (Mþ), calcd for
C17H16N2O3: M, 296.1161.
Research Project of the Natural Science Foundation of the Jiangsu
HigherEducationInstitutions(No.10KJA150049). AProjectFundedby
the Priority Academic Project Development of Jiangsu Higher Edu-
cation Institutions, the Foundation of Key Laboratory of Organic
Synthesis ofJiangsuProvince(No. JSK0812) and Key Project inScience
& Technology Innovation Cultivation Program of Soochow University.
4.2.13. 2-Amino-3-(4-chlorophenyl)-6,7-dimethoxyquinoline-1-
oxide (3e). White solid; mp: >300 ꢀC; IR (KBr)
n: 3429, 3406, 3006,
2968, 2933, 1677, 1608, 1515, 1409, 1271, 1164, 1094, 986, 833, 769,
659 cmꢁ1. 1H NMR (300 MHz, DMSO-d6): dH 3.84 (s, 3H, CH3O), 3.89
(s, 3H, CH3O), 7.27 (s, 1H, ArH), 7.43 (s, 1H, ArH), 7.62 (dd, J1¼8.4 Hz,
J2¼17.1 Hz, 5H, ArH), 7.95 (s, 2H, NH2). HRMS found: m/z 330.0771
(Mþ), calcd for C17H15N2O335Cl: M, 330.0771.
Supplementary data
Supplementary data related to this article can be found online at
http://dx.doi.org/10.1016/j.tet.2012.07.049.
4.2.14. 2-Amino-3-(4-bromophenyl)-6,7-dimethoxyquinoline-1-
oxide (3f). White solid; mp: >300 ꢀC; IR (KBr)
n: 3421, 3401, 3043,
References and notes
2927, 1677, 1607, 1516, 1459, 1409, 1269, 1164, 1084, 985, 832, 767,
651 cmꢁ1. 1H NMR (300 MHz, DMSO-d6): dH 3.84 (s, 3H, CH3O), 3.89
(s, 3H, CH3O), 7.27 (s,1H, ArH), 7.43 (s,1H, ArH), 7.53 (d, J¼8.1 Hz, 2H,
ArH), 7.74e7.83 (m, 3H, ArH), 7.94 (s, 2H, NH2). HRMS found: m/z
374.0272 (Mþ), calcd for C17H15N2O379Br: M, 374.0266.
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ꢀ
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ꢁ
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4.2.15. 6-Amino-7-phenyl-[1,3]dioxo[4,5-g]quinoline-5-oxide
P.; Tordo, P.; Kalyanaraman, B. FEBS Lett. 2000, 473, 58e62.
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(3g). White solid; mp: >300 ꢀC; IR (KBr)
n
: 3416, 3405, 3056, 2910,
1676, 1628, 1522, 1479, 1445, 1256, 1208, 1118, 1038, 943, 834, 753,
671 cmꢁ1 1H NMR (300 MHz, DMSO-d6): dH 6.21 (s, 2H, OCH2O),
.
7.41e7.42 (m, 2H, ArH), 7.53e7.56 (m, 1H, ArH), 7.60e7.62 (m, 5H,
ArH), 7.95 (s, 2H, NH2). HRMS found: m/z 280.0849 (Mþ), calcd for
C16H12N2O3: M, 280.0848.
10. Kim, J. N.; Lee, K. Y.; Kim, H. S.; Kim, T. Y. Org. Lett. 2000, 2, 343e345.
11. Lee, K. Y.; Kim, J. M.; Kim, J. N. Tetrahedron 2003, 59, 385e390.
12. Zbigniew, W.; Andrej, K.; Mieczyslaw, M. Synthesis 1993, 31e32.
13. Makosza, M.; Kmiotek-Skarzynska, I.; Jawdosiuk, M. Synthesis 1977, 56e58.
ꢀ
14. Colacino, E.; Andre, C.; Martinez, J.; Lamaty, F. Tetrahedron Lett. 2008, 49,
4.2.16. 2-Aminoquinoline-1-oxide (3h). White solid; mp: >300 ꢀC.
4953e4955.
15. Prasad, M. R.; Kamalakar, G.; Madhavi, G.; Kulkarni, S. J.; Raghavan, K. V. Chem.
Commun. 2000, 1577e1578.
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rahedron Lett. 2008, 49, 6933e6935.
17. Shi, D. Q.; Dou, G. L.; Ni, S. N.; Shi., J. W.; Li, X. Y.; Wang, X. S.; Wu, H.; Ji, S. J.
Synlett 2007, 2509e2512.
18. Shi, D. Q.; Dou, G. L.; Zhou, Y. Synthesis 2008, 2000e2006.
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1797e1801.
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23. Crystallographic data for the structures of 2e has been deposited at the Cambridge
Crystallographic Data Centre, deposit number is CCDC-837216. Copies of available
material can be obtained free of charge on application to CCDC, 12 Union Road,
Cambridge CB21EZ, UK (fax: þ441223 336 033; e-mail: deposit@ccdc.cam.ac.uk).
IR (KBr) n: 3428, 3359, 3318, 1633, 1525, 1389, 1210, 1053, 812,
754 cmꢁ1. 1H NMR (300 MHz, DMSO-d6): dH 7.30e7.31 (m, 1H, ArH),
7.40e7.41 (m, 1H, ArH), 7.69e7.72 (m, 1H, ArH), 7.90e7.91 (m, 3H,
ArHþNH2), 8.04e8.06 (m,1H, ArH), 9.04 (t, J¼4.5 MHz,1H, ArH). 13
C
NMR (100 MHz, DMSO-d6): dC 156.8, 144.9, 141.5, 139.8, 137.6, 134.4,
129.6, 120.3, 119.4. HRMS found: m/z 161.0716 (MþH)þ, calcd for
C9H9N2O: MþH, 161.0715.
Acknowledgements
We acknowledge the financial support from the Foundation of the
Natural Science Foundation of China (No. 21072144), the Major Basic