Synthesis and Biological Activities of 1-Azaaurone Derivatives

Article abstract of DOI:10.1002/jhet.3190

A series of 1-azaaurone derivatives were designed and synthesized from 3,5-dimethoxyaniline and 2-chloroacetonitrile. Their structures were characterized by melting point, ¹H NMR, IR, and elemental analysis, as well as ¹³C NMR. The t

Full text of DOI:10.1002/jhet.3190

Month 2018
Synthesis and Biological Activities of 1-Azaaurone Derivatives
*
*
Ting Li, Min Qian, Kailu Li, Yukun Qin, Ting Zhao, and Liu-Qing Yang
Min Zhang,
School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, China
*
E-mail: zhangmin@ujs.edu.cn; yangliuqing@ujs.edu.cn
Received January 31, 2018
DOI 10.1002/jhet.3190
Published online 00 Month 2018 in Wiley Online Library (wileyonlinelibrary.com).
A series of 1-azaaurone derivatives were designed and synthesized from 3,5-dimethoxyaniline and
2-chloroacetonitrile. Their structures were characterized by melting point, 1H NMR, IR, and elemental
analysis, as well as 13C NMR. The target compounds were evaluated for antitumor activities against human
hepatocellular liver carcinoma cell line (HepG-2) and human cervix carcinoma cell line (Hela) using methyl
thiazolyl tetrazolium method. The results revealed that several 1-azaaurones exhibited strong proliferation
inhibition efficacy against HepG-2 and Hela with an IC50 range of 5.6–8.8 μg/mL without damaging
normal cell.
J. Heterocyclic Chem., 00, 00 (2018).
INTRODUCTION
In one of our previous studies [18], it was found that 6-
substituted aurones possessed excellent antitumor effects
against HepG-2, Hela, and MCF-7 cancer cell lines, and
the variations of substituents at the A-ring and/or B-ring
could cause remarkable changes in the activity. On the
other hand, some examples support that the presence of
methoxy moieties at C-4 and C-6 positions of aurones
may lead to a substantial increase in the activity
[4,19,20]. Collectively, it is of interest to synthesize 1-
azaaurones bearing methoxyl groups at C-4 and C-6
positions and possessing diverse substituents at the
B-ring, to evaluate their preliminary antitumor activity
and to explore the structure–activity relationship.
Aurones, a subclass of naturally occurring flavonoids, are
met in vegetables, flowers, and fruits where they contribute
to the yellow or orange color [1]. They were also used by
plants to resist pathogens [2], pests [3], and competitive
weeds [4,5]. Recently, increasing attention has been
focused on aurones because both natural aurones and
synthetic analogs exhibited excellent antitumor [6,7],
antioxidant [8,9], antibacterial, and anti-inflammatory
[10,11] activities, as well as acted as potent
multifunctional defense agents against Alzheimer’s disease
[12,13]. In addition, aurones have been proved to be
valuable inhibitors of human tyrosinase to prevent
hyperpigmentation-related abnormality [14,15]. These
studies indicate that aurone has evolved to be an excellent
leading scaffold for the development of various analogs
with significant biological activity.
RESULTS AND DISCUSSION
Synthesis.
The synthetic pathway of title compounds
was summarized in Scheme 1. 1-(2-Amino-4,6-
dimethoxyphenyl)-2-chloroethan-1-one (1) was synthesized
from 3,5-dimethoxyaniline and 2-chloroacetonitrile in the
presence of trichloroborane and dry aluminum
trichloride, followed by hydrolysis according to the
reported procedure [21]. Treatment of 1 with acetic
anhydride in the presence of potassium carbonate
produced N-acetyl-4,6-dimethoxyindolin-3-one (2) in
1-Azaaurone, an isosteric equivalent replacement of
aurone by replacing intracyclic O atom at 1-position with
NH group (Fig. 1), has been found to display important
bioactivity [7,16,17]. Moreover, some azaaurones
exhibited much stronger bioactivity than the parent
aurones. For example, Souard et al. reported that
azaaurone analogs demonstrated better antiplasmodial
activity in comparison with corresponding aurones [16].
© 2018 Wiley Periodicals, Inc.

M. Zhang, T. Li, M. Qian, K. Li, Y. Qin, T. Zhao, and L.-Q. Yang
Vol 000
3l, and 3m displayed an inhibition rate of higher than
60% against both HepG-2 and Hela. Regarding antitumor
activity against HepG-2, the structure–activity relationship
(Table 1) confirmed that the presence of electron-
withdrawing group at the B-ring led to less active
compounds (3c, 3d, and 3k vs 3a), while those with a
donating-electron group at the B-ring showed a little
better inhibitory effect (3e, 3f vs 3a). Further, two
electron-donating groups at the B-ring led to a dramatic
increase in the activity (3l, 3m vs 3a). It was also found
that hydroxyl group at C-40 position was highly beneficial
when 3l was compared with 3m. With regard to the
activity against Hela, the presence of electron-donating
group at the B-ring was highly advantageous (3f, 3h–3j
vs 3a–3d, 3k); further, two methoxyl groups at C-30 and
C-40 positions led to the most potent compound (3l vs 3i,
3j). However, when the methoxy moiety at C-40 position
was replaced by hydroxyl group, the activity decreased
slightly (3m vs 3l). Taken together, possessing the
electron-donating groups at the B-ring is beneficial to the
antitumor activity of 1-azaaurones but is disadvantageous
to that of aurones [18], which is probably correlated to
the difference of O atom and NH group at 1-position.
On the basis of the screening results, compounds 3f, 3j,
3l, and 3m were selected to further evaluate their IC50
values against cancer cell lines HepG-2 and Hela, as well
as normal human hepatic cell line (WRL-68) with
Aurone A as a reference control, which is the most
active aurone derivative in our previous work [18]. As
shown in Table 2, each of them was active with IC50
value below 10 μg/mL. The most active compound was
3m with IC50 values of 5.6 and 6.3 μg/mL against HepG-
2 and Hela comparative to IC50 values of Aurone A (8.4
and 3.3 μg/mL), respectively. More interestingly,
compounds 3l and 3m were proved to be ineffective
against WRL-68 with IC50 values of 74.1 and 62.4 μg/
mL, respectively. These results implied that 1-azaaurone
derivatives selectively inhibited cancer cell lines without
damaging normal cell. Moreover, these 1-azaaurones
displayed much higher inhibition toward Hela than the
aurones described in the literature [22], which might also
Figure 1. Basic structures of aurone and 1-azaaurone.
Scheme 1. Synthetic route of the title compounds.
good yield. The target 1-azaaurone derivatives 3a–3m
were obtained by the condensation of 2 with various
arylaldehydes in H2O/EtOH under alkali condition. Six
of them (3d, 3e, 3g, and 3k–3m) are new compounds.
1
The target compounds were confirmed by H NMR, IR,
and elemental analysis, as well as 13C NMR. These 1-
azaaurones were identified exclusively as
Z
1
stereoisomers on the basis of the H chemical shifts of
exocyclic vinyl proton (═CH─), which appeared at δ
1
6.38–6.84 ppm in H NMR, corresponding to the known
values (ca. 6.70 ppm) for (Z)-aurones [4,8,12].
Biological activity. The preliminary antitumor activities
of all synthetic 1-azaaurones against HepG-2 and Hela
were evaluated using methyl thiazolyl tetrazolium (MTT)
assay [18]. As demonstrated in Table 1, most of the
compounds were active toward HepG-2 and Hela at the
concentration of 10 μg/mL. For example, compounds 3f,
Table 1
Antiproliferative activities of 1-azaaurones 3a–3m (inhibition% at 10 μg/mL).
Compound
HepG-2
Hela
NA
31.8
8.75
NA
17.7
65.5
22.7
Compound
HepG-2
Hela
3a
3b
3c
3d
3e
3f
55.4
55.3
43.6
16.8
60.3
63.2
50.5
3h
3i
3j
3k
3l
3m
51.6
46.7
50.5
36.3
63.7
82.6
54.8
54.4
60.9
16.5
80.0
71.7
3g
NA, no activity.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2018
Synthesis and Biological Activities of 1-Azaaurone Derivatives
Table 2
In vitro antitumor activities of some target compounds (IC50, μg/mL).
reported method [21]. A solution of intermediate 1
(1.15 g, 5.0 mmol), K2CO3 (0.83 g, 6.0 mmol) in acetone
(30 mL) was stirred at room temperature till all solid was
dissolved. Then, the solution was treated with acetic
anhydride (1.08 g, 10.6 mmol) and heated under reflux
until completion of the reaction (monitored via thin-layer
chromatography). The resulting solution was poured into
ice water after cooling. The formed solid was filtered off,
washed with water, dried, and recrystallized from EtOH
to afford product 2 in 60% yield, mp 93–95°C.
Compound
HepG-2
Hela
WRL-68
3f
3j
3l
7.5
8.0
7.4
5.6
8.4
7.8
6.7
8.8
6.3
3.3
ND
ND
74.1
62.4
ND
3m
Aurone Aa
ND, no detection.
a
General synthetic procedure for 1-azaaurones 3a–3m.
Oxindole 2 (0.24 g, 1.0 mmol) was dissolved in EtOH
(5 mL) then treated with KOH solution (10%, 5 mL).
The corresponding arylaldehyde (1.2 mmol) was added to
the mixture. Then, the solution was heated at 50°C for 3–
5 h. EtOH was evaporated after the reaction was finished
by thin-layer chromatography monitoring. Ice water was
added to the residue, followed by neutralizing with
hydrochloric acid solution (2 mol/L). The precipitate was
collected by filtration, washed with water three times, and
purified by recrystallization from EtOH to yield
compounds 3a–3m.
, reported in our previous work [18].
be attributed to the replacement of the intracyclic O atom
by the NH group.
In conclusion, a series of 1-azaaurones were designed
and synthesized, and their antitumor activities against
cancer cell lines HepG-2, Hela, and normal cell WRL-68
were evaluated. The preliminary bioassay demonstrated
that some 1-azaaurones selectively inhibited cancer cell
lines without damaging normal cell. The structure–
activity relationship revealed that the substituents at the
B-ring played an important role on the activity. The
present investigation brings essential elements, which will
help to design and synthesize more potent azaaurones.
(Z)-2-Benzylidene-4,6-dimethoxy-2,3-dihydro-1H-indol-3-
one (3a).
Compound 3a has been reported previously
1
[23,24]. Yellow solid, yield 83.0%, mp 134–136°C. H
NMR (400 MHz, CDCl3) δ: 3.86 (s, 3H, OCH3), 3.93 (s,
3H, OCH3), 5.93 (d, J = 1.6 Hz, 1H, ArH), 6.06 (d,
J = 2.0 Hz, 1H, ArH), 6.75 (s, 1H, ═CH), 6.84 (br s, 1H,
NH), 7.29–7.34 (m, 1H, ArH), 7.39–7.45 (m, 2H, ArH),
7.49–7.53 (m, 1H, ArH). IR (KBr) v: 3404, 3068, 1672,
1624, 1597, 1585, 1464, 1451, 1398, 1364, 1263, 1223,
1211, 1159, 1126, 1050 cmꢀ1. Anal. Calcd for C17H15NO3:
C 72.58, H 5.37, N 4.98. Found: C 72.26, H 5.53, N 5.20.
EXPERIMENTAL
IR spectroscopy were recorded on a Nicolet Nexus 470
spectrometer (Nicolet Instrument Corporation, Madison,
WI) as KBr pellets. Melting points were uncorrected and
obtained using an X-4 digital melting point apparatus.
NMR spectra were recorded on a Bruker AVANCEII
400 MHz instrument (400 MHz for 1H, 100 MHz for
(Z)-2-(2-Fluorobenzylidene)-4,6-dimethoxy-2,3-dihydro-1H-
indol-3-one (3b). Compound 3b has been reported in the
literature [19]. Orange solid, yield 68.4%, mp 110–
1
113°C. H NMR (400 MHz, DMSO-d6) δ: 3.83 (s, 3H,
13C). Elemental analysis was carried out with
FLASH1112A analyzer (CE Instruments Ltd, Milan, Italy).
1-(2-Amino-4,6-
a
OCH3), 3.85 (s, 3H, OCH3), 6.01 (d, J = 2.0 Hz, 1H,
ArH), 6.19 (d, J = 2.0 Hz, 1H, ArH), 6.44 (s, 1H, ═CH),
7.25–7.33 (m, 2H, ArH), 7.35–7.41 (m, 1H, ArH), 7.76–
7.82 (m, 1H, ArH), 9.76 (br s, 1H, NH). IR (KBr) v:
3362, 3088, 2978, 1667, 1626, 1577, 1516, 1513, 1467,
1438, 1372, 1296, 1252, 1219, 1198, 1153,
1119,1017 cmꢀ1. Anal. Calcd for C17H14FNO3: C 68.22,
H 4.71, N 4.68. Found: C 68.46, H 4.53, N, 5.05.
Synthesis
of
compound
1.
dimethoxyphenyl)-2-chloroethan-1-one (1) was prepared
basing on the procedure [21] from the reaction of 3,5-
dimethoxyaniline (3.06 g, 20.0 mmol) and 2-
chloroacetonitrile (23.6 mmol) in dry dichloromethane
(20 mL), in the presence of trichloroborane (23.6 mmol)
and anhydrous aluminum trichloride (2.93 g, 22.0 mmol)
at 0°C. After working up, the reaction solution was
treated with hydrochloric acid solution (2 mol/L),
followed by heating at 80°C for 0.5 h. The resulting
solution was extracted three times with CH2Cl2, washed
with water, dried with Na2SO4, and followed by removing
the solvent to give a yellow solid, yield 70%, mp 90–92°C.
(Z)-2-(3-Fluorobenzylidene)-4,6-dimethoxy-2,3-dihydro-1H-
indol-3-one (3c). Compound 3c has been reported in the
literature [25]. Orange solid, yield 66.3%, mp 95–96°C.
1H NMR (400 MHz, DMSO-d6) δ: 3.82 (s, 3H, OCH3),
3.85 (s, 3H, OCH3), 6.01 (d, J = 1.6 Hz, 1H, ArH), 6.20
(d, J = 1.6 Hz, 1H, ArH), 6.38 (s, 1H, ═CH), 7.11–7.18
(m, 1H, ArH), 7.43–7.54 (m, 3H, ArH), 9.79 (br s, 1H,
NH). IR (KBr) v: 3412, 3036, 1627, 1590, 1511, 1458,
1380, 1242, 1218, 1156, 1120, 1050, 1009 cmꢀ1. Anal.
Synthesis
of
compound
2.
N-Acetyl-4,6-
dimethoxyindolin-3-one (2) was prepared according to a
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DOI 10.1002/jhet

M. Zhang, T. Li, M. Qian, K. Li, Y. Qin, T. Zhao, and L.-Q. Yang
Vol 000
Calcd for C17H14FNO3: C 68.22, H 4.71, N 4.68. Found: C
67.91, H 4.93, N 4.97.
(Z)-2-(4-Fluorobenzylidene)-4,6-dimethoxy-2,3-dihydro-1H-
214–216°C. 1H NMR (400 MHz, CDCl3) δ: 3.85 (s,
3H, OCH3), 3.91 (s, 3H, OCH3), 3.92 (s, 3H, OCH3),
5.88 (d, J = 1.6 Hz, 1H, ArH), 6.00 (d, J = 2.0 Hz,
1H, ArH), 6.84 (s, 1H, ═CH), 6.93–7.03 (m, 2H,
ArH), 7.27–7.34 (m, 2H, ArH + NH), 7.46 (dd,
J = 7.6, 1.2 Hz, 1H, ArH). IR (KBr) v: 3377, 2933,
2840, 1671, 1630, 1589, 1511, 1489, 1463, 1434,
1381, 1264, 1246, 1218, 1157, 1117, 1029 cmꢀ1. Anal.
Calcd for C18H17NO4: C 69.44, H 5.50, N 4.50.
indol-3-one (3d).
Orange solid, yield 68.9%, mp 108–
1
110°C. H NMR (400 MHz, DMSO-d6) δ: 3.82 (s, 3H,
OCH3), 3.84 (s, 3H, OCH3), 5.99 (d, J = 1.6 Hz, 1H, ArH),
6.19 (d, J = 1.6 Hz, 1H, ArH), 6.40 (s, 1H, ═CH), 7.24–
7.31 (m, 2H, ArH), 7.67–7.75 (m, 2H, ArH), 9.73 (br s,
1H, NH). 13C NMR (100 MHz, DMSO-d6) δ: 55.4, 55.6,
88.6, 90.6, 103.0, 105.9, 115.7 (d, J = 21.4 Hz, 2C), 130.9
(d, J = 3.2 Hz), 131.4 (d, J = 8.0 Hz, 2C), 135.1, 157.0,
159.6, 161.3 (d, J = 245.3 Hz), 167.9, 181.3. IR (KBr) v:
3420, 3032, 1626, 1595, 1507, 1462, 1380, 1262, 1217,
1162, 1128 cmꢀ1. Anal. Calcd for C17H14FNO3: C 68.22,
Found: C 69.65, H 5.44, N, 4.24.
(Z)-2-(3-Methoxylbenzylidene)-4,6-dimethoxy-2,3-dihydro-
1H-indol-3-one (3i).
Compound 3i has been reported
previously [24]. Orange-yellow solid, yield 85.0%, mp
1
187–189°C. H NMR (400 MHz, CDCl3) δ: 3.83 (s, 3H,
H 4.71, N 4.68. Found: C 68.01, H 4.90, N 4.89.
(Z)-2-(2-Methylbenzylidene)-4,6-dimethoxy-2,3-dihydro-1H-
OCH3), 3.85 (s, 3H, OCH3), 3.90 (s, 3H, OCH3), 5.91 (d,
J = 1.6 Hz, 1H, ArH), 6.05 (d, J = 2.0 Hz, 1H, ArH),
6.69 (s, 1H, ═CH), 6.84 (dd, J = 8.0, 2.0 Hz, 1H, ArH),
6.99 (br s, 1H, NH), 7.00–7.03 (m, 1H, ArH), 7.07–7.12
(m, 1H, ArH), 7.29–7.35 (m, 1H, ArH). IR (KBr) v:
3426, 3077, 2942, 1667, 1626, 1592, 1516, 1463, 1385,
1256, 1216, 1158, 1120, 1051 cmꢀ1. Anal. Calcd for
C18H17NO4: C 69.44, H 5.50, N 4.50. Found: C 69.67, H
indol-3-one (3e).
Yellow solid, yield 82.6%, mp 213–
214°C. 1H NMR (400 MHz, CDCl3) δ: 2.38 (s, 3H, CH3),
3.84 (s, 3H, OCH3), 3.92 (s, 3H, OCH3), 5.90 (d,
J = 2.0 Hz, 1H, ArH), 6.00 (d, J = 1.6 Hz, 1H, ArH), 6.81
(br s, 1H, NH), 6.84 (s, 1H, ═CH), 7.17–7.25 (m, 3H,
ArH), 7.47–7.51 (m, 1H, ArH). 13C NMR (100 MHz,
CDCl3) δ: 20.0, 55.7, 55.8, 88.1, 91.0, 105.1, 107.5,
126.2, 127.9, 128.0, 130.7, 133.8, 136.8, 138.1, 156.5,
160.4, 168.5, 181.9. IR (KBr) v: 3420, 3095, 2966, 1674,
1607, 1517, 1462, 1370, 1257, 1217, 1200, 1154, 1123,
1033, 1001 cmꢀ1. Anal. Calcd for C18H17NO3: C 73.20,
H 5.80, N 4.74. Found: C 73.01, H 5.95, N 4.50.
5.26, N 4.74.
(Z)-2-(4-Methoxylbenzylidene)-4,6-dimethoxy-2,3-dihydro-
1H-indol-3-one (3j). Compound 3j has also been reported
in the literature [24]. Yellow solid, yield 87.3%, mp 213–
215°C. 1H NMR (400 MHz, CDCl3) δ: 3.83 (s, 3H,
OCH3), 3.84 (s, 3H, OCH3), 3.89 (s, 3H, OCH3), 5.90 (d,
J = 1.6 Hz, 1H, ArH), 6.08 (d, J = 1.6 Hz, 1H, ArH),
6.73 (s, 1H, ═CH), 6.93 (d, J = 8.8 Hz, 2H, ArH), 6.97
(br s, 1H, NH), 7.46 (d, J = 8.8 Hz, 2H, ArH). IR (KBr)
v: 3421, 3089, 2929, 1630, 1591, 1509, 1467, 1366,
1299, 1253, 1217, 1176, 1160, 1119, 1029 cmꢀ1. Anal.
Calcd for C18H17NO4: C, 69.44; H 5.50, N 4.50. Found:
(Z)-2-(3-Methylbenzylidene)-4,6-dimethoxy-2,3-dihydro-1H-
indol-3-one (3f).
Compound 3f has been reported
previously [24]. Yellow solid, yield 65.1%, mp 168–
170°C. 1H NMR (400 MHz, CDCl3) δ: 2.38 (s, 3H, CH3),
3.85 (s, 3H, OCH3), 3.90 (s, 3H, OCH3), 5.91 (d,
J = 1.6 Hz, 1H, ArH), 6.08 (d, J = 2.0 Hz, 1H, ArH), 6.71
(s, 1H, ═CH), 7.01 (br s, 1H, NH), 7.08–7.12 (m, 1H,
ArH), 7.28–7.33 (m, 3H, ArH). IR (KBr) v: 3244, 2970,
2848, 1675, 1605, 1511, 1458, 1430, 1370, 1262, 1216,
1158, 1119, 1046 cmꢀ1. Anal. Calcd for C18H17NO3: C
73.20, H 5.80, N 4.74. Found: C 73.54, H 5.62, N 4.90.
(Z)-2-(4-Methylbenzylidene)-4,6-dimethoxy-2,3-dihydro-1H-
C 69.35, H 5.66, N 4.35.
(Z)-2-(3-Trifluoromethylbenzylidene)-4,6-dimethoxy-2,3-
dihydro-1H-indol-3-one (3k). Yellow solid, yield 77.4%,
1
mp 160–162°C. H NMR (400 MHz, CDCl3) δ: 3.86 (s,
3H, OCH3), 3.90 (s, 3H, OCH3), 5.92 (d, J = 0.8 Hz, 1H,
ArH), 6.11 (d, J = 0.8 Hz 1H, ArH), 6.69 (s, 1H, ═CH),
7.10 (br s, 1H, NH), 7.49–7.54 (m, 2H, ArH), 7.64–7.69
(m, 1H, ArH), 7.70–7.73 (m, 1H, ArH). IR (KBr) v:
3444, 3036, 1683, 1599, 1471, 1386, 1328, 1279, 1219,
1160, 1117, 1070 cmꢀ1. Anal. Calcd for C18H14F3NO3: C
indol-3-one (3g).
Yellow solid, yield 84.2%, mp 187–
189°C. 1H NMR (400 MHz, CDCl3) δ: 2.37 (s, 3H,
CH3), 3.85 (s, 3H, OCH3), 3.91 (s, 3H, OCH3), 5.91 (d,
J = 1.6 Hz, 1H, ArH), 6.07 (d, J = 2.0 Hz, 1H, ArH),
6.74 (s, 1H, ═CH), 6.91 (br s, 1H, NH), 7.21 (d,
J = 8.0 Hz, 2H, ArH), 7.40 (d, J = 8.0 Hz, 2H, ArH). 13C
NMR (100 MHz, CDCl3) δ: 21.3, 55.7(2C), 88.3, 91.1,
105.0, 109.9, 129.2(2C), 129.7(2C), 132.1, 135.8, 138.2,
156.5, 160.3, 168.4, 182.4. IR (KBr) v: 3285, 3100, 2998,
1683, 1630, 1610, 1590, 1508, 1463, 1383, 1319, 1254,
1214, 1158, 1115, 1042 cmꢀ1. Anal. Calcd for C18H17NO3:
61.89, H 4.04, N 4.01. Found: C 61.65, H 4.31, N 4.24.
(Z)-2-(3,4-Dimethoxylbenzylidene)-4,6-dimethoxy-2,3-
dihydro-1H-indol-3-one (3l).
Yellow solid, yield 83.6%,
1
mp 137–139°C. H NMR (400 MHz, CDCl3) δ: 3.83 (s,
3H, OCH3), 3.88 (s, 3H, OCH3), 3.89 (s, 3H, OCH3),
3.91 (s, 3H, OCH3), 5.90 (d, J = 1.6 Hz, 1H, ArH), 6.08
(d, J = 1.6 Hz, 1H, ArH), 6.68 (s, 1H, ═CH), 6.87 (d,
J = 8.0 Hz, 1H), 7.00 (d, J = 1.6 Hz, 1H, ArH), 7.06 (br
s, 1H, NH), 7.12 (dd, J = 8.4, 1.6 Hz, 1H, ArH). 13C
NMR (100 MHz, DMSO-d6) δ: 55.4, 55.5, 55.6(2C),
88.5, 90.5, 103.3, 108.1, 111.9, 113.3, 122.6, 127.1,
C 73.20, H 5.80, N 4.74. Found: C 72.95, H 6.11, N 4.94.
(Z)-2-(2-Methoxylbenzylidene)-4,6-dimethoxy-2,3-dihydro-
1H-indol-3-one (3h). Compound 3h has been reported
in the literature [25]. Yellow solid, yield 67.1%, mp
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2018
Synthesis and Biological Activities of 1-Azaaurone Derivatives
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134.2, 148.8, 148.9, 156.9, 159.4, 167.6, 181.3. IR (KBr)
v: 3432, 3020, 1667, 1627, 1590, 1510, 1465, 1369,
1271, 1249, 1216, 1160, 1116, 1025 cmꢀ1. Anal. Calcd
for C19H19NO5: C 66.85, H 5.61, N 4.10. Found: C
66.95, H 5.33, N 3.86.
(Z)-2-(4-Hydroxy-3-methoxybenzylidene)-4,6-dimethoxy-2,3-
dihydro-1H-indol-3-one (3m). Yellow solid, yield 85.3%,
1
mp 259–260°C. H NMR (400 MHz, DMSO-d6) δ: 3.81
(s, 3H, OCH3), 3.84 (s, 3H, OCH3), 3.85 (s, 3H, OCH3),
5.97 (d, J = 2.0 Hz, 1H, ArH), 6.20 (d, J = 2.0 Hz, 1H,
ArH), 6.39 (s, 1H, ═CH), 6.84 (d, J = 8.4 Hz, 1H, ArH),
7.13–7.21 (m, 2H, ArH), 9.42 (s, 1H, OH), 9.51 (br s, 1H,
NH). IR (KBr) v: 3363, 3015, 2921, 1665, 1625, 1577,
1513, 1470, 1445, 1372, 1296, 1252, 1219, 1198, 1153,
1119, 1042, 1019 cmꢀ1. Anal. Calcd for C18H17NO5: C
66.05, H 5.23, N 4.28. Found: C 66.30, H 5.21, N 4.44.
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were seeded into 96-multiwell plate (4 × 103 cells/well)
and incubated for 24 h. Different concentrations of each
test compound were added to the cells triplicate wells. The
cells without test compounds were used as negative
controls. Following the exposure of 48 h to the test
compound, MTT solution (100 μL/well, 1 mg/mL) was
added to each well and left for another 4 h. After removing
MTT, dimethyl sulfoxide was added to the cell to dissolve
the precipitate, and the absorbance (Abs) of each well was
measured at 570 nm using the ELISA reader (Spectra
MAX 190, Molecular Devices Corporation, USA). The
inhibitory effect was calculated as follows: Inhibition
(%) = (1 ꢀ Abscompound/Abscontrol) × 100. IC50 was
obtained for each test compound using SPSS 16.0 version
(SPSS Inc., Chicago, USA).
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Acknowledgments. We are very grateful for the financial support
from the National Natural Science Foundation of China (no.
31501686), the Natural Science Foundation of Jiangsu Province
(BK20140536), and the Jiangsu Government Scholarship for
Overseas Studies (JS-2016-100).
SUPPORTING INFORMATION
REFERENCES AND NOTES
Additional supporting information may be found online
in the Supporting Information section at the end of the
article.
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Yonekura-Sakakibara, K.; Yamaguchi, M.; Nakayama, T.; Tanaka, T.;
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet